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Chapter 7 - Scrapie Flock Certification Program

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Table of Contents

7.1 The disease

Note: The use of the term "scrapie" refers to classical scrapie only; certification does not cover "atypical" scrapie, which is clinically, pathologically, biochemically and epidemiologically unrelated to classical scrapie.

Etiology

Susceptible species

Distribution

Epidemiology

Transmission of scrapie between animals has been documented in the absence of lambing, and infectious prions have been found in feces, saliva and milk from both clinically and sub-clinically infected animals. As a result, pasture previously grazed by infected small ruminants or buildings previously inhabited by them may represent a transmission risk. Further, animals incubating the disease and even animals that never develop clinical signs may be a source of infection to others.

Abnormal prion proteins are extremely resilient with regards to traditional approaches to disinfection, as they are very resistant to both chemical and physical inactivation and stable over a wide pH and temperature range. While they undergo a significant decrease in infectivity titre with time, they have been demonstrated to persist in the environment for years. Reports indicate that environmental contamination as much as 16 years earlier can result in the reintroduction of scrapie infection.

There is no clear evidence to date that implicates semen in the transmission of scrapie. Research studies on the potential of scrapie transmission by embryos have produced conflicting results. The research in this area has been assessed and the World Organisation for Animal Health (OIE) Terrestrial Animal Health Code currently states that when authorizing import or transit of in-vivo sheep-derived embryos, no scrapie-related conditions should be required, regardless of the scrapie risk status of the sheep and goat populations of the exporting country, zone or compartment. This applies as long as the embryos are handled in accordance with OIE embryo collection and processing requirements. However, due to conflicting studies on embryos, there continues to be a higher standard with respect to acquisition of embryos in the SFCP.

Genetic effects

Genetic makeup has been determined to be a significant factor in a sheep's susceptibility to infection with scrapie. At the present time, studies on goat genetics and scrapie susceptibility are more limited and less clear.

Current evidence indicates that there are different forms of the sheep prion protein. Some forms are highly susceptible to the structural transformation to the abnormal form found in scrapie, while others are resistant to this change. As in all mammals, sheep are diploid organisms, so that all cells contain two copies of each chromosome and, thus, two copies of the gene that codes for the normal prion protein. Genes are made up of codons. A codon is a stretch of DNA that determines which particular amino acid will be included at a particular location of a protein (in this case, the prion protein). The prion protein is composed of 256 amino acids; therefore, there are 256 codons determining these amino acids. In the literature concerning susceptibility to various strains of scrapie, three codons are discussed: 171, 154 and 136. In North America, two of these codons are given primary importance: 171 and 136. The presence of an arginine (R) at codon 171 of the prion protein confers resistance to the infectious scrapie prion protein. The presence of glutamine (Q) or histidine (H) – treated the same as a Q at codon 171 – is associated with susceptibility to the infectious scrapie prion protein. An alanine (A) at codon 136 confers resistance to the scrapie prion protein, while the presence of valine (V) at codon 136 confers greater susceptibility. V at site 136 is linked with Q at site 171, such that R cannot be found at site 171 in combination with V at site 136.

Scrapie susceptibility as defined by the codons 171 and 136 is as follows:
Sheep's genotype (136, 171) Susceptibility to classical scrapie
AA RR Negligible
AA QR Very low
AV QR Intermediate
AA QQ
AV QQ
VV QQ
High

It is still not definitively known whether animals with less susceptible genotypes do not become infected with the scrapie agent or whether they are merely protected from developing the clinical signs of scrapie.

The vast majority of positive cases of scrapie that have been genotyped in North America have been determined to be homozygotes for QQ at codon 171. Small numbers of QRs around the world have tested positive for scrapie. In these cases, the amino acids at codon 136 are examined and heterozygotes for A and V at codon 136 appear to indicate greater susceptibility among the QR population. Although no cases of scrapie with 171RR genotype have been reported in North America, a couple of cases have been reported in Europe.

Recent science indicates that the genotype of the fetus influences the migration and accumulation of abnormal prion in the placenta of an infected ewe. The placenta of a 171QQ infected ewe carrying a 171QQ fetus accumulates large quantities of abnormal prion, which is then shed during birth or abortion. However, the abnormal prion does not accumulate in the placenta of a fetus with a 171QR or 171RR genotype. This means that use of a 171RR ram can prevent the shedding of abnormal prion at lambing, even from infected ewes.

It is important for producers to understand that scrapie genotyping is not disease testing. A 171QQ sheep does not automatically have scrapie, just as there is no absolute guarantee that a 171RR sheep cannot get scrapie. The CFIA does not intend to mandate the Canadian sheep flock to breed for scrapie resistance; rather, scrapie genotyping is a tool that can be used in an overall plan to manage the risk of scrapie on a particular premises. Whether or not a particular producer can or should use scrapie genotyping is a decision to be made based on individual factors such as breed, the prevalence of 171RR within the flock, the management of the ewe flock and the current status of other breeding indices.

Goats

Genetic makeup as a factor in a goat's susceptibility to infection with scrapie is the topic of ongoing international and Canadian research. In the literature multiple variations in the goat prion gene have been associated with varying levels of scrapie resistance. Different alleles have been targeted in the research due in part to the differing frequencies of these potential alleles in the various goat populations depending on breed and region of origin. Variable protective effects against scrapie in goats have been reported for alleles S127, M142, S146, D146, H154, Q211 and K222, with S/D 146 and K222 currently considered to show the most promise. While sheep genotyping is used in the SFCP, goat genotyping is not yet incorporated into the program.

Clinical signs

Differential diagnosis

Laboratory diagnosis

Detection of abnormal prions by live animal testing with either third eyelid biopsy or recto-anal mucosa-associated lymphoid tissue (RAMALT) biopsy has highspecificity; however, it has lower sensitivity with false negatives occurring. To maximize sensitivity, third eyelid testing should be applied to ewes over 14months of age with the genotype 171QQ. Similarly, RAMALT testing should be applied to ewes over 12 months of age with the genotype 171QQ, and does over 12 months of age. Lymphoid tissue testingis a useful screening tool for the presence of infection in a flock, but it is not a reliable indicator of individual freedom from disease.

Scrapie genotyping is not testing for disease; it is a screening test that indicates a sheep's relative susceptibility for scrapie. When one is trying to find infection, sheep with the highest susceptibility are the subpopulation in which one is most likely to discover the disease.

Immunity

Public health

7.2 Policy and principles of control

Policy statement

The Scrapie Flock Certification Program (SFCP) is a voluntary Canadian program that small ruminant producers can choose to join. Any owner of sheep or goat premises who agrees to comply with the SFCP may apply to enroll; however, once they are participating in the Program, their compliance with the National Standards is mandatory. The objective of the SFCP is to provide owners with the opportunity to have their flocks/herds identified as negligible risk with respect to scrapie. The Program certifies flocks/herds with respect to classical scrapie only, and does not cover atypical scrapie, which is clinically, pathologically, biochemically and epidemiologically unrelated to classical scrapie.

The Program is designed to give producers a means of detecting and controlling scrapie within their flock/herd, resulting in recognition that the risk of their animals being infected with scrapie diminishes to negligible with progressive participation in the Program. Being a participating flock/herd and reaching certified and certified plus status in the Program provides assurances to potential purchasers that the animal for sale is coming from a negligible-risk flock/herd. Recognition of this status can provide market access opportunities domestically and internationally. This Program also provides a valuable vehicle for surveillance for scrapie within Canada, contributing to the National Scrapie Eradication Program.

Statutory authority

Scrapie is a reportable disease under the Reportable Diseases Regulations, prescribed in accordance with Section 2 of the Health of Animals Act. Any person suspecting an animal of demonstrating signs consistent with scrapie must report that animal to a federal veterinarian at a CFIA district office.

The primary role of the federal government in the SFCP is to establish the National Standards and to audit for compliance with these standards.

Export certification

Animals from flocks/herds enrolled in the SFCP may be certified and endorsed by the CFIA as participating in a program that meets the minimum national standards. The CFIA will work to gain international recognition of the minimum national standards. Certificates documenting participation and level in the SFCP are obtained from the regional administrator, Canadian Sheep Federation (CSF).

Principles for control and eradication

While there are no tests to definitively rule out scrapie in the individual live animal, there are a number of tools that can be used to evaluate the risk of scrapie being present in a sheep flock or goat herd. Ways used to determine the SFCP status on a flock/herd basis include post-mortem testing, RAMALT testing, genotyping, absence of clinical signs and prevention of exposure to scrapie over a designated period of time.

The pathway to achieve certified status for sheep or goats on the SFCP relies on being on the program for 5 years, surveillance of mature animals that die, the absence of clinical signs, and preventing the exposure to scrapie. The next level, certified plus, requires a minimum number of samples to be tested for scrapie and 7 years on the program.

A scrapie suspect is any animal that has scrapie as a differential diagnosis.

The CFIA implements disease investigation procedures as soon as a clinical suspect is reported.

A scrapie-positive animal is any animal for which scrapie-positive results were reported by the CFIA's National and OIE Reference Laboratory for Scrapie, using at least two CFIA-approved scrapie tests (for example ELISA, immunohistochemistry, Western blot) applied to the brain and/or lymphoid tissue.

Any confirmed cases of scrapie results in immediate suspension from the SFCP. The CFIA implements strict disease eradication measures to eliminate the infection from the premises where it was detected, to determine the source of infection and to identify any spread of the infection from the premises that may have occurred and eliminate it.

7.3 Accredited veterinarian's responsibilities

Preliminary activities

General responsibilities

Annual physical inspection, inventory and report

Deadstock testing

Live Animal testing

Sick animals

Scrapie Flock Certification Program status levels

7.4 National Standards for the Scrapie Flock Certification Program

Introduction

Participation in the Scrapie Flock Certification Program (SFCP) is optional. The program is designed to give producers a means of detecting and controlling scrapie within their flock/herd, resulting in recognition that the risk of their animals being infected with scrapie diminishes to negligible with progressive participation in the program. A sheep or goat producer can join the SFCP provided that the producer agrees to adhere to the program rules. The program certifies flocks/herds with respect to classical scrapie only, and does not cover "atypical" scrapie which is clinically, pathologically, biochemically and epidemiologically unrelated to classical scrapie. Atypical scrapie may, in fact, be a non-contagious, spontaneous degenerative condition of older sheep. As such, throughout this document, when the term "scrapie" is used, it refers to classical scrapie only.

Since there is no test to to rule-out the disease in the individual live animal, "scrapie-negligible-risk" status is based on the results of surveillance testing carried out on deadstock, screening the flock/herd for presence of disease, removing genetically susceptible animals, restricting animals entering the flock/herd, and the absence of clinical signs.

The Program involves limiting acquisitions to animals from similar or higher status flocks/herds and ongoing surveillance through the submission of all deadstock for scrapie testing. The program includes seven levels, from the entry level (level E) to the certified level, with the addition of a higher level of certified plus. The certified plus level is for flocks which desire to be recognized as more fully aligned with OIE requirements. A minimum of five years (one year each at level E, D, C, B, A) is necessary to reach the certified level. A minimum of 7 years, along with additional sampling requirements is necessary to reach the certified plus level.

The SFCP is used for trade between owners/ farm operators within Canada, for export outside of Canada, and for individual risk mitigation on enrolled farms.

The SFCP is carried out in co-operation with producers, accredited veterinarians, national stakeholder organizations, provincial governments, approved laboratories and the Canadian Food Inspection Agency (CFIA). The roles assumed by each of these organizations may vary in different regions of Canada.

1. Roles and responsibilities

1.1 National standards development and audit

This role and the associated responsibilities will be assumed by the CFIA in all situations. The CFIA is responsible for the development, using a consultative process, of national (minimum) standards for a scrapie flock certification program. Modifications and updates to these standards will be undertaken as required. The CFIA is responsible for providing the current national standards to the organizations responsible for regional administration (see point 1.2 below).

Where the regional administration is assumed by organizations other than CFIA, it is the CFIA's responsibility to review any scrapie flock certification program proposed for the specific region of Canada and determine equivalency to the published national voluntary scrapie flock certification program standards. International negotiation for recognition of the program and endorsement of export certification by the CFIA will only be done for those scrapie flock certification programs judged by the CFIA to meet the national standards.

The CFIA is responsible for conducting audits of program design and implementation to verify that the scrapie flock certification program in a particular region of Canada meets the national standards.

The CFIA is responsible for the design and implementation of a quality assurance program for non-CFIA laboratories performing transmissible spongiform encephalopathy (TSE) testing, and laboratories providing genotyping for scrapie susceptibility. All confirmatory testing on suspect or positive scrapie tissue samples will be performed by a CFIA laboratory. In the case of a confirmed positive animal, the CFIA will implement the National Scrapie Eradication Program, the official disease control program of Canada. Discrepancies between genotyping results from two laboratories will be subject to final genotype testing by a CFIA laboratory.

The CFIA is responsible for ensuring a publicly accessible report for example published on the website of all enrolled flocks and herds and their status is maintained. This report will be updated on a quarterly basis.

1.2 Regional administrator

This role and the associated responsibilities may be assumed by a national or provincial industry group, the provincial government or the CFIA Program Network. The regional administrator is responsible for overseeing enrolment and membership in the scrapie flock certification program for a particular region of Canada, including the following:

1.3 Status assessment or status assessor

The role of assessor of flock/herd status may be assumed by a national or provincial industry group, the provincial government or the CFIA district office. The status assessor is responsible for the following:

1.4 Program delivery

Program delivery is carried out by a veterinarian accredited by the CFIA. A CFIA veterinarian or a veterinarian who is an employee of a provincial department that is the status assessor or regional administrator may also carry out program delivery, and can be substituted anywhere the services of an accredited veterinarian is required in the standards. The inventory portion of the initial or annual report may be conducted by an accredited veterinarian, an animal health technician supervised by the accredited veterinarian, a CFIA veterinarian, or staff of a provincial department or agency that is the status assessor or regional administrator.

Veterinary practitioners are authorized (accredited) by the CFIA or the appropriate provincial government to perform inspections, to take samples for diagnostic or genotyping purposes and to check records.

To obtain accreditation, a veterinarian must successfully complete the training indicated in the Accredited Veterinarian's Manual or its provincial equivalent.

The accredited veterinarian must sign the application form completed by the owner.

If the owner decides to stop doing business with the accredited veterinarian who signed the original application form, the new accredited veterinarian must be asked to sign a copy of the form, or - if the situation has changed - a new application form.

In rare instances where a flock or herd has been subject to CFIA disease control actions as a result of being declared positive for scrapie, a CFIA veterinarian may act as the program delivery person for the SFCP during the CFIA's mandatory follow-up period for deadstock surveillance.

Program delivery personnel are responsible for the following:

1.5 Laboratories

Laboratory approval is accompanied by training and implementation of a quality assurance program established by the CFIA. A member of the laboratory staff must have taken CFIA training in order to be able to supervise scrapie tests and ensure that the quality assurance program is followed. Laboratories providing diagnostic testing services for the SFCP are responsible for the following:

1.6 Producers

In this program, an owner is a person who owns the premises and the animals on the premises. A producer is a person who has responsibility for the care and handling of all animals on a premises; this person may or may not be the owner.

The owner of a flock/herd wishing to enrol in the SFCP is responsible for the following:

2. Administration

2.1 Enrolment procedure

The flock owner contacts the local CFIA district veterinarian to determine the organizations responsible for the SFCP in the region in which the flock/herd is located.

The owner contacts the SFCP regional administrator and requests an application package.

The owner may only join one pathway to certification at a time. Specifically, any flock/herd and all the individual animals within the flock/herd can only be registered in one pathway to certification at a time.

An application package is completed and submitted to the organization responsible for status assessment. The applicant must indicate which Program Specific Pathway to Certification will be pursued. The application must be accompanied by the following:

Accelerated admission to more advanced levels of the SFCP may be possible for flocks/herds which have met all program requirements for a number of years prior to application or are from a program considered equivalent in terms of risk reduction.

A flock/herd that has been subject to the CFIA's National Scrapie Eradication Program may be admitted to the certification program at the entry level (level E) of the SFCP provided all scrapie eradication program requirements have been completed, and any declarations of infected place or quarantines have been removed.

Owners who will be starting a new flock/herd with acquired animals of status D or higher and who intend to keep that status will need to follow all regular application form protocols as above, but in addition, provide a letter (written by the owner) stating that the premises where the flock will reside meets one of the following conditions:

In cases where owners will be starting a new flock/herd with acquired animals of status D or higher and they intend to keep that status on a premises that, within the last 10 years, has previously contained (or it is unknown whether it previously contained) small ruminants, all regular application form protocols as above will need to be followed, and the owner will agree to follow the approved cleaning and disinfection protocol for the SFCP under the supervision of their accredited veterinarian prior to stocking any animals on the property. To retain the higher status, it will be necessary for the accredited veterinarian to certify to the administrator that the cleaning and disinfection has been done in a satisfactory manner prior to stocking the animals on the premises.

Flock/herd owners successfully enrolling in the SFCP and quitting the SFCP within the same 24-month period will not be permitted to re-enrol in the SFCP for a period of three years from their date of departure from the program (subject to appeal).

In addition, flock/herd owners who obtain temporary enrolment and do not complete the requirements for full enrolment in the SFCP will not be permitted to re-enrol in the SFCP for a period of three years from their date of acceptance for temporary enrolment (subject to appeal).

2.2 Advancement and downgrading

An owner may apply to have the certification status of the flock/herd upgraded if the following conditions are met:

To upgrade the certification status of the flock/herd, the owner must submit a request along with the annual report that would make them eligible for advancement to the status assessor for review and approval. The request must be completed and signed by the owner and the accredited veterinarian on record.

The status assessor reviews the annual report and approves advancement or identifies deficiencies that prevent advancement.

When deficiencies are identified, the status assessor may require that the current level be maintained until the deficiencies are addressed, or that the status of the flock/herd be downgraded or suspended. The decision is documented to the program participant and copied to the accredited veterinarian and the regional administrator.

Owners successfully participating in the SFCP (at level E or above) who have purchased one or more females from a non-enrolled or level E flock/herd, resulting in downgrading to status E (or penalty to remain at level E), will not be permitted to introduce additional females from non-enrolled or level E flocks/herds for a period of three years from the date of their previous introduction or downgrading within the program (subject to appeal).

Once the certified level is reached, an owner may choose to keep the flock/herd at certified level, or may apply for advancement to the certified plus level if the additional requirements are met.

Once a flock/herd has attained the certified level, or certified plus level, annual request for renewal of this level is required. To maintain their status of certified or certified plus, the owner must submit an annual report, documenting that all ongoing requirements have been met, to the status assessor for review and approval. The report must be completed and signed by the owner and the accredited veterinarian responsible for the flock/herd.

2.3 Suspension/revoking of registration/appeals

If the owner of a registered flock/herd contravenes the program rules, the organization responsible for status assessment will temporarily suspend the certification status of the flock/herd, and after reviewing the situation, may reinstate at the same level, downgrade, or revoke the status of the flock/herd and remove it from the program.

An owner whose flock/herd is under review for possible removal from the program will be given the opportunity to submit any relevant information to the status assessor, provided that this is done no later than 30 days after suspension.

Any owner who fails to submit an inspection report within the month following the end of the anniversary quarter will have their flock/herd automatically suspended.

The status assessor will notify the owner and the accredited veterinarian in writing of the reasons for the decision and give the owner the opportunity to appeal within the following 60 days. The notice will include the name and address of the responsible person within the appeal committee as established by the status assessor.

An owner whose flock/herd has been removed from the program due to contravention of program rules may submit a new application after meeting the conditions stipulated in the program. In such a case, the owner must submit satisfactory proof to the status assessor that steps have been taken to ensure that the flock/herd will meet the program requirements in the future. In the case of a flock/herd that is reinstated in the program, the reinstatement level will depend on the reasons for suspension. The flock/herd will not be automatically reinstated at its previous level. In cases where the flock/herd was removed for reasons of information falsification, failure to report to a veterinary inspector that an animal might have scrapie, or any other action that might expose other animals to scrapie, an owner may lose the privilege of registering in the program.

If a participating flock/herd is found to be either infected with, or a source of scrapie, its certification status will be immediately revoked and it will be removed from the program. The flock/herd will be subject to the CFIA's scrapie eradication program governed by the Health of Animals Act and the Health of Animals Regulations. The flock/herd may re-enroll at the entry level (level E) of the SFCP provided all scrapie eradication program requirements have been completed, and any declarations of infected place or quarantines have been removed.

If it is determined, as part of a CFIA scrapie disease investigation, that scrapie exposed animals may have resided in a SFCP flock/herd, then the flock/herd will have its status immediately suspended and will be subject to CFIA's scrapie eradication program. The exposed flock/herd's status is reinstated only once all requirements of CFIA's scrapie eradication program are complete and all testing is negative. These requirements include genotyping and scrapie testing all genetically susceptible exposed animals. If it is determined that the exposed animals are no longer in the flock and cannot be located and tested, then the corresponding CFIA's scrapie eradication program requirements for this situation must be followed. If any of the unavailable exposed animals are genetically susceptible breeding females, then the flock/herd may only re-enroll at the entry level of the SFCP.

A producer may appeal a decision regarding advancement or downgrading in the event of an incomplete or unsatisfactory application for advancement. A producer may also appeal a temporary suspension or a revocation of registration, but not both.

2.4 Reports

The results of all reports, including information on registrations, tests, suspensions, revocations, and changes in status, are distributed to the owner, the accredited veterinarian and the CFIA district veterinarian.

The regional administrator will maintain a list of all flocks and herds enrolled in the program, the pathway and their current level on the Scrapie Canada website. Flock/herds for which a report is not submitted to the status assessor within the prescribed time will be identified on the website as being suspended.

The quarterly report published by the CFIA will be produced and automatically distributed to all provinces, and/or published on the website. It will list all registered and certified flocks and herds, along with their pathway and certification levels.

Records must be kept of feed given to animals, according to the Health of Animals Act and the Health of Animals Regulations.

2.5 Review of the program

The SFCP will be reviewed on an annual basis and/or as the scientific information becomes available and changes are required.

3. General rules

These requirements must be met by participants in all three certification pathways.

3.1

The certification program must be open to any owner of a premises on which sheep or goats are kept, provided that the owner and the premises meet the program requirements and the owner of the premises has not had the right to participate in the SFCP removed (revoked).

3.2

All sheep and goats on a premises must be included in the flock/herd enrolled in the certification program, ownership notwithstanding.

3.3

Multiple premises must be listed under the same certification contract if the premises belong to the same owner and are located contiguous to each other.

Multiple premises that are non-contiguous to each other still need to be included under the same certification contract if the small ruminants on the premises meet the definition of established herd.

Multiple non-contiguous premises may be permitted to be enrolled under different certification contracts (such as different flocks/herds with separate statuses) if they are not considered an established herd (see definition), including no exchange of animals, and no direct or indirect (shared use of pasture, facilities, equipment) contact of animals.

3.4

The flock/herd owner must arrange for the services of an accredited veterinarian (or equivalent) to deliver the SFCP. The accredited veterinarian's acceptance of their role in implementation of the SFCP within the identified flock/herd is reflected by their signature on the application form.

3.5

The owner of a flock/herd must report to their accredited veterinarian any sheep or goat with any clinical sign associated with scrapie and any illness in a sheep or goat over 12 months of age lasting longer than two weeks, except a physical injury. The owner may not dispose of the animal unless the accredited veterinarian determines the signs are not consistent with scrapie. The accredited veterinarian must maintain a written record of each such determination. The accredited veterinarian will be responsible for monitoring the outcome of the case and for reporting the case to the CFIA if scrapie is a differential diagnosis. If CFIA determines the animal may be a scrapie suspect, then CFIA's scrapie eradication program procedures must be followed. If the flock/herd is found to be infected with scrapie or a source of scrapie, its certification status will be immediately suspended. The flock/herd will be subject to the CFIA's scrapie eradication program governed by the Health of Animals Act and the Health of Animals Regulations.

3.6

All animals aged 12 months or more must be identified with two unique identification devices.

3.7

Animals less than 12 months of age must be identified in a manner that enables the owner to track these animals in the flock/herd inventory. All animals aged less than 12 months must be appropriately identified (as required by regulation) when a change in ownership occurs or when the animals are moved outside their usual location (for example to an exhibition, insemination centre, sales barn or auction barn).

3.8

The owner must keep detailed flock/herd records of every sheep or goat that is born on or enters the premises, no matter who the owner is or who is responsible for the sheep or goat. The records must be kept for a period of five years after the animal has left the flock/herd or has died. They must be made available to the program delivery person or the CFIA inspector at any reasonable time and must be presented at the time of each annual inventory.

For all animals in the flock/herd, the basic minimum data that must be maintained in records and submitted as part of annual reports includes the following:

3.9

Sheep or goat milk, colostrum or their derived products destined for use in sheep or goats may only be sourced from sheep or goats in the same flock/herd or from a flock/herd on the SFCP of greater or equal status as the recipient flock. Sheep or goat milk, colostrum or their derived products from a lower status flock/herd or a flock/herd not enrolled in the program will result in downgrading in status of the recipient flock /herd. Sheep and goat milk and colostrum or their derived products from a scrapie – positive animal, a scrapie suspect animal or a genetically susceptible exposed animal (136AA 171QQ, 136AV 171QQ, 136VV 171QQ, 136AV 171QR) may not be used. Bovine milk and colostrum and their derived products may be used. Appropriate biosecurity standards should be applied when sourcing milk and colostrum from any source including bovine.

Flock/herd inventories

3.10

Inventories (initial and annual) will be conducted by the accredited veterinarian or an appropriate third party supervised by the accredited veterinarian. The inventory will identify all sheep and goats on the premises. During the inventory inspection, all animals over 12 months of age in the flock/herd must be identified individually (by tag) and the veterinarian must check for any clinical symptoms of scrapie. For extremely large flocks/herds using electronic inventories, all animals over 12 months of age must be identified individually and their identifiers must be physically verified over the course of the year. However, only a statistically significant random sampling must have their identifiers physically verified during the annual inventory inspection. Sampling tables are available upon request. If a flock/herd inspection is performed by a CFIA veterinary inspector for the purposes of the scrapie disease control program, this may replace part or all of the annual inspection by the accredited veterinarian.

Annual reports

3.11

The annual report lists the following:

The report must be forwarded to the status assessor within the anniversary quarter in which the certified flock/herd was registered. The status category is effective from the date when the flock/herd is accepted within the program, and the anniversary quarter for subsequent years is the quarter in which the acceptance date falls (Jan. 1-March 31; April 1-June 30; July 1-Sept. 30; Oct. 1-Dec. 31).

In all cases, the owner is ultimately responsible for clarifying any inventory questions/concerns that may arise during the course of the review of the annual report by the status assessor.

Scrapie samples

3.12

A post-mortem sample for the SFCP requires two tissues, a brain sample (that includes the obex) and a retropharyngeal lymph node. The medial retropharyngeal lymph node is targeted as it typically remains with the head when removed and is accessible. One lymph node is required to be tested, but submit both to ensure suitable tissue is available. In situations where retropharyngeal lymph nodes are unavailable the mandibular lymph node or tonsil would be accepted.

The head (containing the brain and medial retropharyngeal lymph nodes) of the animal may be submitted directly to an approved laboratory by the producer, or the accredited veterinarian may collect brain and lymph node samples for submission to either an approved laboratory or to a CFIA district office to be sent to a CFIA laboratory (as part of the national scrapie surveillance program). The brain and lymph node samples may be collected by a trained third party under the supervision of the accredited veterinarian however, the responsibility of the sample collection and submission remains with the accredited veterinarian. In all cases, the head (or the samples) should be chilled or frozen immediately.

The owner must contact the laboratory or the accredited veterinarian must contact the CFIA district office in advance before submitting a head. The head must bear animal identification.

3.13

A live animal sample for the SFCP requires either a rectal biopsy obtaining a sample of recto-anal mucosal lymphoid tissue (RAMALT) or a third eyelid biopsy obtaining a sample of third eyelid lymphoid tissue. Samples are collected by the accredited veterinarian, or by a trained third party under the supervision of the accredited veterinarian (the responsibility of the sample collection and submission remains with the accredited veterinarian), and subjected to testing for scrapie by a laboratory approved by the CFIA for that purpose. Live animal testing is restricted to animals over 14 months of age and, if sheep, of genotype 171QQ.

3.14

If the animal is a scrapie suspect or implicated in a scrapie disease investigation, sampling is done by CFIA and according to National Scrapie Eradication Program procedures.

If a submitted sample results in a scrapie positive test result, action on the flock/herd is per section 2.3 Suspension/Revoking of Registration/Appeals.

3.15

A brain and lymph node sample from all sheep or goats over 12 months of age owned by the producer that die or are humanely destroyed, other than those sent for routine slaughter, must be submitted for scrapie testing by a CFIA-approved laboratory.

If the dead animal is not found immediately, or the accredited veterinarian and the laboratory are not available within 36 hours of death, the head (containing the brain and medial retropharyngeal lymph nodes) of the animal must be frozen by the owner and submitted as a frozen specimen. Freezing enables the scrapie diagnostic test to be applied to the tissues which otherwise would no longer be suitable for testing.

3.16

Animals older than 12 months which are submitted for routine post-mortem may be considered as dead submissions for the annual minimum sampling requirements if tested for scrapie.

Genetically susceptible sheep or goats over 14 months tested by live-animal sampling or post-mortem sampling (culled, slaughtered animals) may be used to meet the minimum sampling requirement for the Certified Plus level.

3.17

Specimens must meet the requirements specified in the diagnostic protocol approved by the CFIA, which guarantees the reliability and accuracy of the results. If an unsuitable specimen is received, the receiving laboratory is to notify the status assessor and accredited veterinarian responsible for the flock/herd. A follow-up of the details of the individual situation will be undertaken with the responsible accredited veterinarian or status assessor. If negligence on the part of the producer is identified as the cause, or this occurrence is repeated, then the program's requirements are not considered to have been met and the flock/herd will be suspended.

3.18

It is not necessary to submit for testing more than five adult animals from a group of animals that die from a common cause as determined by a veterinarian or veterinary pathologist within the time frame (not to exceed four weeks) of the same epidemiologically linked episode.

Exemption from submission of heads

3.19

The status assessor should consider the following as automatic exemptions from the requirement to submit unless the status assessor suspects that the conditions set out were not met or that the exemption is being abused to the detriment of the flock certification program.

A. Destruction of sheep by fire

A certificate or letter from an appropriate fire official must accompany the annual report.

B. The destruction and carrying away of the head of a sheep by a predator

A certificate or letter from an appropriate wildlife officer or other government official responsible for investigating such incidents must accompany the annual report.

C.Theft

A report of the police officer who investigates the theft must accompany the annual report.

D. Loss or destruction of the sample when it is no longer in the control of the owner (for example by an accredited veterinarian or laboratory). Recognized laboratories should note on reception of the specimen that the obex and/or lymph node is not present and the reason why.

A letter setting out the details of the loss of the sample by the individual responsible must accompany the annual report.

E. Any other reason over which the owner could not reasonably be expected to have control which results in the destruction or disappearance of the body, such as a flood

A letter or report by an acceptable third party which sets out the details of the reason for failure to submit the sample must accompany the annual report.

Genotype samples and testing

3.20

Samples (for example blood samples) required for genotyping may be taken by a veterinarian accredited to deliver the SFCP or a third party under the supervision of a veterinarian accredited to deliver the SFCP (for example a veterinary student, a technician). Approved identifiers are required on sheep being genotyped and the official identification number (15 digits) included with the sample submission.

3.21

The genotype of 136AA 171RR breeding rams must be determined twice: by using a combination of predictive parentage and testing by a laboratory approved by the CFIA, or a combination of testing at any laboratory and at a laboratory approved by the CFIA. Genotype results with only codon 171 for those animals determined to be 171RR are considered acceptable. This is due to the knowledge that R cannot be found at site 171 in combination with V at site 136 (V at site 136 is linked with Q at site 171).

Accordance between the results of the two separate determinations of genotype is required. In cases of discordance, a separate sample will be taken from the animal and submitted to the CFIA lab for determination of the genotype.

Breeding ewes that require genotyping may have their genotype determined through the use of predictive parentage or laboratory analysis.

Samples for genotyping of female sheep may be submitted to any laboratory approved by the CFIA.

Genotyping two different tissues (blood, hair follicle or buccal swab) should be considered especially for confirming genotype in 136AA 171QR animals due to the phenomenon of blood chimerism. There are limitations of the standard blood sample in this rare situation of a chimeric animal.

Information sharing

3.22

Information sharing requires all flock/herd information, including inventories, test results, documents related to purchases and sales of animals or embryos, deaths, to be available to the owner, the CFIA, the status assessor, the regional administrator and the accredited veterinarian. The owner must also agree to allow publication of the status of the flock/herd under the program.

4. Advancement in status (levels E, D, C, B, A and certified)

4.1

The program includes seven levels (E, D, C, B A, certified, and certified plus). With the entry level being level E and the highest level being certified plus. Advancement through each level from E to certified occurs annually if all program requirements are met. The owner must make an annual request for advancement or maintenance of the flock/herd status within the SFCP. An annual report including animal inventory and all supporting documentation must be submitted to the status assessor.

Advancement to certified status

A minimum of five years (one year each at level E, D, C, B, A) is necessary for an enrolled flock/herd to reach the certified level. Once a flock/herd has reached the certified level, it maintains this level provided that the applicable requirements continue to be met. All requirements in section 4 and the previous sections must be met.

Advancement to certified plus status

Two further years, for a minimum of 7 years, and additional sampling minimums are required to advance to the certified plus level. Section 5 details the requirements to advance to the certified plus level.

Sampling requirements

4.2

The status category is effective from the date when the flock/herd is accepted within the program, and the anniversary quarter for subsequent years is the quarter in which the acceptance date falls (January 1-March 31; April 1-June 30; July 1-September 30; October 1-December 31).

4.3

A brain and retropharyngeal lymph node sample from all sheep or goats over 12 months of age owned by the producer that die or are humanely destroyed, other than those sent for routine slaughter, must be submitted for scrapie testing by a CFIA-approved laboratory.

4.4

One-hundred per cent of animals older than 12 months owned by the producer that die or are humanely destroyed, other than those send for routine slaughter, are to be submitted for scrapie testing. Animals that are unavailable for testing beyond the automatic exemptions detailed in these standards will be considered as per policy detailed by the status assessor. A program participant who does not agree with the decision of the status assessor may appeal the decision.

4.5

a) If no suitable samples have been submitted for testing for a period of time equal to or exceeding 12 months, at least one animal 18 months of age or older, which has resided in the flock/herd for no less than 18 months, is to be humanely destroyed (in any manner: slaughter, euthanasia) and a sample (that includes brain and retropharyngeal lymph node), submitted for testing. If the flock is genotyped, then select a genetically susceptible animal to be humanely destroyed for testing. If humanely destroying an animal for deadstock testing will have a significant impact on the flock or herd due to its small size, a producer enrolled on pathway 1 may be able to advance using the alternative live animal sampling protocol detailed in d) below.

b) Alternatively if no suitable samples have been submitted for testing for a period of time equal to or exceeding 12 months, an enrolled producer may be permitted to remain on the program without advancing to the next level for one additional year (allowing time to raise an animal for slaughter and testing). For certified producers, they would incur a one year status penalty dropping them from certified to Level A.

c) The annual sampling minimum is waived for genetically resistant flocks, defined as all sheep in the flock with documented proof of 136AA 171QR or 171RR genotype, and all rams of 171RR genotype. The genotype of 136AA 171RR breeding males must be determined twice and the genotype of breeding females must be determined once as described in sections 3.20 and 3.21 under General Rules. All animals owned by the producer that die or are humanely destroyed, other than those sent for routine slaughter, must still be submitted for scrapie testing as per 4.3 and 4.4.

d) Alternative live animal sampling protocol

To be eligible for advancement live animal sampling must include the following:

Animal acquisitions

4.6

Introduction of female animals or embryos from the following sources, with a supporting zoosanitary health certificate, will have no impact on the certification level:

4.7

A) Introduction of males from flocks/herds from the following sources, with supporting documentation, will have no impact on the certification level and these males will acquire the status of the flock/herd:

B) Introduction of males from any flocks/herds and kept in the following manner will have no impact on the certification level:

4.8

The flock/herd status certificate accompanying the purchase of the animals or embryos will be the supporting document required to attest to the certification level of the flock/herd of origin.

4.9

Introduction of one or more animals or embryos obtained from flocks/herds registered in the SFCP at the same certification level but registered in a later anniversary quarter will result in the recipient's anniversary quarter being moved to that of the flock/herd of origin. If one or more animals or embryos from a non-participating flock/herd are introduced, the enrolled producer's anniversary quarter will change to the quarter in which the new animal(s) or embryo(s) were introduced, in addition to the penalty to downgrade to or remain at level E. Anniversary quarter will not be affected for flocks where these embryos or males have been introduced and have met the genotype requirement as set out in 4.6 or 4.7. Anniversary quarter will not be affected for flocks or herds where males have been introduced and met the requirements to be maintained separately as set out in 4.7.

4.10

If animals or embryos from flocks/herds of a lower certification level are introduced, the status of the recipient flock/herd will be downgraded to that of the flock/herd of origin of the lowest category. If animals or embryos from a non-participating flock/herd are introduced, the status of the recipient flock/herd will be reduced to level E. Anniversary quarter will not be affected for flocks where these embryos or males have been introduced and have met the genotype requirement as set out in 4.6 and 4.7. Anniversary quarter will not be affected for flocks or herds where these males have been introduced and met the requirements to be maintained separately as set out in 4.7.

4.11

With the exception of limited contacts (see definitions), commingling of animals from non-participating flock/herds or a flock/herd of a lower status will result in downgrading of the certification level to that of the flock/herd of origin of the lowest category (level E if animals are commingled with animals from a non-participating flock/herd).

4.12

Semen may be sourced from males in non-participating flocks/herds or flocks/herds of any certification level, with no impact on the certification level of the recipient flock/herd, provided that, on the date of insemination, the semen donor is not affected by scrapie (positive animal) or suspected of being affected by scrapie or from a scrapie exposed susceptible animal. The semen must meet the requirements of the national artificial insemination program.

4.13

The producer must make an annual request for advancement or maintenance of the flock/herd status within the SFCP. The request must be accompanied by the annual report including animal inventory, and all supporting documentation must be submitted to the status assessor.

Once certified status is achieved, the producer makes an annual request to maintain certified status for their herd/flock or, once the additional requirements are met, the producer may make a request for advancement to the certified plus level.

5. Advancement to certified plus status

5.1

All program requirements in the previous sections must continue to be met for advancement to certified plus status and to maintain certified plus status. Additional requirements to be met in order to advance to certified plus status are detailed in this section.

5.2

To attain certified plus status a flock/herd must have been enrolled for a minimum of 7 years with a minimum of 30 animals scrapie tested or the equivalent as set out in 5.3.

5.3

a) The minimum sampling requirement for the flock/herd to advance to certified plus status is 30 animals scrapie tested or all genetically susceptible animals over 14 months of age scrapie tested whichever is less. This minimum sampling requirement is met by any combination of the following:

b) In addition to the minimum sampling requirement above, any genetically susceptible female animals not acquired from certified plus flocks in the preceding two years must be sampled by live-animal or post-mortem testing before advancement.

5.4

Once certified plus status is achieved, the producer must make an annual request to maintain certified plus status for their herd/flock. The owner must submit an annual report that documents that all ongoing requirements have been met, to the status assessor for review and approval. The request must be completed and signed by the owner and the accredited veterinarian responsible for the flock/herd.

Definitions

Commingled (mixed):
animals grouped together with physical contact between the animals. This does not include limited contact (for example contact through a fence, pen separation during a show/sale). Commingling includes sharing the same section in a transportation unit where physical contact can occur. (Mélangés (mêlés))
Contiguous:
Premises which share common boundaries and where co-mingling of small ruminants can occur between the two premises. (Aire contiguë)
Established flock or herd:
all animals that are maintained on a single premises and all animals under common ownership or supervision on two or more premises with animal interchange between the premises or indirect contact including shared use of housing, facilities or pasture.(Troupeau établi)
Flock or herd:
as defined in the Health of Animals Regulations. (Troupeau)
Flock/herd status certificate:
document issued by the regional administrator specifying the location and status of the flock/herd, indicating the date of issue, and identifying animals leaving the flock/herd following their sale. (Certificat de statut du troupeau)
Limited contact:
incidental contacts between animals off the premises of the flock/herd such as at fairs, shows, exhibitions and sales and semen collection facilities. Limited contact does not include any contact, incidental or otherwise, with an animal during or up to 30 days after she lambed, kidded or aborted or when there is any visible vaginal discharge. Limited contacts do not include any activity where uninhibited contact occurs, such as sharing an enclosure, sharing a section of a transport vehicle, or residing in the other flock/herd for breeding or other purposes. (Contact limité)
Scrapie exposed susceptible animal:
Any goat and any sheep of 171QQ or 136AV 171QR genotype that has resided on a premises while it was declared scrapie infected by a competent authority (CFIA). (Animal sensible exposé à la tremblante)
Scrapie positive:
An animal for which scrapie-positive results were reported by the CFIA's National and OIE Reference Laboratory for Scrapie, using at least two CFIA-approved scrapie tests (for example ELISA, immunohistochemistry, Western blot) applied to the brain and/or lymphoid tissue. (Animal positif à la tremblante)
Scrapie suspect:
Any animal that has scrapie as a differential diagnosis. (Animal suspect à l'égard de la tremblante)
Unique identification devices:
permanent, unique, traceable and secure (for example electronic identification, tattoo, tamper evident tag). Until the national mandatory identification program for goats is implemented, neck chains and collars are acceptable as one form of identification in goats. (Dispositif d'identification unique (identifiant unique))
136AA:
includes all results that identify the animal as a homozygote for alanine (A) at codon 136 of the scrapie prion gene. (AA en 136)
136AV:
includes all results that identify the animal as a heterozygote for valine (V) and alanine (A) at codon 136 of the scrapie prion gene. (AV en 136)
136VV:
includes all results that identify the animal as a homozygote for valine (V) at codon 136 of the scrapie prion gene. (VV en 136)
171QQ:
includes all results that do not identify arginine (R) at codon 171 of the scrapie prion gene (includes glutamine and histidine; QQ, QH, HH). (QQ en 171
171QR:
includes all results that do not identify the animal as a homozygote for arginine (R) at codon 171 of the scrapie prion gene, identifying arginine on one allele and the absence of arginine on the other (includes glutamine and histidine; QR or HR). (QR en 171)
171RR:
includes all results that identify the animal as a homozygote for arginine (R) at codon 171 of the scrapie prion gene. (RR en 171)

7.5 Appendices

Appendix A: brain sampling procedures

Entire heads may be submitted fresh or frozen to an approved laboratory.

Scrapie is not considered to be a human pathogen; however, normal sanitary precautions against a possible range of pathogens should be taken. Wear protective clothing, gloves and face protection when collecting brain specimens. Always avoid direct contact with brain tissues. Personnel at tissue harvesting sites should take precautions to avoid ingestion of the agent.

Precautions against the transmission of disease to small ruminants and the environment are warranted. It is recommended that the animal's head be placed on a disposable plastic drop sheet. The sheet should be large enough to cover the work area. As prions are particularly resistant to standard physical and chemical methods of decontamination, see Appendix E for appropriate disinfectants.

This is an image of the grapefruit spoon and knife

Figure 1 – Different examples of obex spoons

obex harvesting technique

Recommended tools:

Additional tools that you may choose to use:

The obex removal spoon or knife may be fashioned from the Zwilling J.A. Henckels – Jessica Grapefruit spoon or knife, respectively. Alternatively, any butter knife or suitably long and concave spoon (6 mm concavity) can be modified. The edges of the knife must be sharpened. The edges of the spoon should be cut down to measure 22-26 mm at the widest point and sharpened to a blade.

Figure 2 – Photo of a sheep head dorsal side down for correct orientation

With the aid of an autopsy knife, disarticulate the head at the level of the atlanto-occipital articulation. Place the head dorsal side down on a table with the foramen magnum (the opening of the spinal canal) facing you.

Using the forceps with your left hand, grasp the dura mater (the thick lining around the spinal cord) and with the scissors in your right hand, make a single cut down the centre line to form two flaps. (This step is not mandatory.) Remove the congealed blood from around the cord.

Figures 3 and 4 – Photos of severing attachments to free up spinal cord

Figure 5 – Photos of severing attachments to free up spinal cord

With the forceps in your left hand holding the dura, sever the cranial nerves from the cord. This can be done with scissors or with the obex spoon/knife by passing the spoon/knife around the cord, keeping the flat side of the spoon/knife against the cord. (See next picture for position of obex spoon/knife in relation to the cord.) This is the most important step in freeing up the cord. The cord must be completely free from attachments (by cranial nerves) in all directions. If you do not sufficiently free up the cord, you will not be able to sample anteriorly enough to get the obex, or one side will be missing.

Insert the obex spoon/knife face down into the vertebral canal and move it forward, lodging the tip as far cranially as it will go. This should position the tip of the spoon/knife over the part of the cord just anterior to the obex and just behind the cerebellar attachments.

Figure 7 – Photo of the removal of the obex from the vertebral canal

Identifying the nerves of the brain - Figure 6. Description follows.

Brain Sampling Procedures - Figure 6

This image represents the cranial nerves. Listing the cranial nerves and other key brain structures from top to bottom: Optic chiasm, Trochlear nerve, Abducens nerve, Vestibulocochler nerve, Vagus nerve, Choroid plexus, Accessory nerve. The sampled portion of cord showing cranial nerves is identified with a rectangle.

Identifying parts of the brain - Figure 8. Description follows.

Brain Sampling Procedures - Figure 8

This image is the diagram of vertebral canal and cerebellar attachments. Listing the parts of the vertebral canal and cerebellum from top left to bottom right: the Foramen magnum, Spinal cord, Obex, Cerebellar attachments, Cerebellum, Top of the skull.

Pick up the head and (if right-handed) hold in left hand, dorsal side down. While pushing down with your index finger, manoeuvre the tip of the obex spoon/knife back and forth over the cord to sever it from the rest of the brain just rostral to the obex and caudal to the cerebellar attachments. Rotate the skull with your other hand in the opposite direction of the spoon/knife to facilitate the cutting of the cord.

Figures 9 and 10 – Photos of manipulating the obex spoon/knife in order to remove the obex

Figures 9 and 10 – Photos of manipulating the obex spoon/knife in order to remove the obex

Figures 11, 12, 13, 14 – Photos of the obex after removal.

Use the obex spoon/knife to gently pull the severed portion of the brain from the canal. The obex is recognizable as a V-shaped depression. This portion is the single most important site for diagnostic testing.

Figures 11, 12, 13, 14 – Photos of the obex after removal.

Figures 11, 12, 13, 14 – Photos of the obex after removal.

Figures 11, 12, 13, 14 – Photos of the obex after removal.

Submission and packaging

Contact the CFIA-approved laboratory to which you will be submitting the samples and request information on preparing the sample for submission (fresh or frozen).

Samples can be frozen and batch-shipped in a frozen state to a CFIA-approved laboratory for enzyme-linked immunosorbent assay (ELISA) testing (if necessary).

As traceability is critical when there is a scrapie positive, it is essential to ensure that the sample submitted is irrefutably linked to the correct animal by documenting national identifiers or other unique identifiers. Submit physical identification device(s) with 1 cm of adjacent tissue. The adjacent tissue will allow DNA verification if required.

Tissues for scrapie surveillance testing may be packaged and shipped as exempt animal specimens in accordance with the Transportation of Dangerous Goods Regulations. The basic four-part packaging system may be used: The specimen must be packaged in a primary watertight receptacle (such as a small sealable plastic bag) with labelling. Enclose this in a second durable watertight packaging with adequate absorbent material to absorb all fluid in case of breakage. Outer packaging, such as a fibreboard box, protects the contents from external physical damage. The description of the contents on the shipper's waybill should include the notation "exempt animal specimen."

Appendix B: collection of retropharyngeal lymph nodes

Figure 15 -Photos of the obex and the medial retropharyngeal lymph nodes (RPLNs)

Lymph nodes are submitted along with the brain (obex) when samples are taken as part of the SFCP. The medial retropharyngeal lymph nodes (RPLNs) are usually chosen, though any other head or neck lymph node is acceptable. The medial RPLNs are medial to the stylohyoid bones on the dorsolateral surface of the pharyngeal muscles and dorsal to the carotid artery. They are medial and deep, and rarely removed by normal dressing procedures.

Figure 16 – Photos on the medial RPLNs situated inside the head

Recommended tools:

Procedure:

  1. Place the head dorsal side down on the table. Remove the skin from the ventral side of the mandible.

    Figure 17 – Photo of removing the skin from the ventral mandible

  2. Grab the pharynx with the non-cutting hand and pull it toward you. Place the knife on the mandibular symphysis, and cut caudally with the blade touching the ventral aspect of the mandible. As you cut caudally, follow the angle of the mandible dorsally, as you approach the rami of the mandible.

    Figure 18 – Photo of cutting  caudally along the mandible

  3. Cut the hyoid bones, or disarticulate them at a joint.
  4. The medial RPLNs are caudal to the nasopharynx. Place your index finger in the nasopharynx and the thumb caudally on the caudal pharyngeal muscles. When the thumb and index finger are brought together, the medial RPLNs can be palpated between them. The opposite node will be about 1 centimetre medial to the first. Dissect medial RPLNs from the surrounding pharyngeal muscles with rat-toothed forceps and scissors, scalpel, or knife

    Figure 19 - Photo of the medial RPLNS location in the head

    Figure 20 - Photo of the medial RPLNS location in the head

    (Above figures are from the USDA sampling guide.)

    Alternative approach

  5. An alternative approach is the caudal approach. Place the head upside down (dorsal side down), with the nose pointing away from sampler, and with the foramen magnum facing sampler. The medial RPLNs lie deep and between the base of the larynx (windpipe) and the floor of the skull. They are "buried" in an area of whitish connective tissue on either side of the pharynx and upper neck and jaw.
  6. To access the buried RPLNs, with a knife, make the first incision, going straight upwards, from just above the foramen magnum to the surface. Make a second cut, extending from where the first cut began, staying close to the base of the skull and moving the knife down and to the right as if you were boning out the tissue. Make the third cut, starting at the same spot above the foramen magnum and going down and to the left, staying close to the skull.
  7. After pulling back/reflecting the two flaps created, notice an area of white connective tissue and fat on either side of the cut. The RPLNs are encapsulated in the white fibrous tissue.

    Bluntly dissect out the beige-coloured, firm nodular lymph nodes buried in the white connective tissue.

    Figure 21 - Photo of location of buried RPLNs

    Figure 22 - Photo of  RPLNs after dissection from connective tissue

    Once RPLN samples are collected

  8. Place the collected RPLNs into a plastic bag for chilling or freezing.
  9. For submission instructions refer to submission and packaging for brain samples in Appendix A.

Appendix C: sampling procedures for genotyping

Samples required for genotyping may be taken by a veterinarian accredited to deliver the VSFCP or a third party under the supervision of a veterinarian accredited to deliver the VSFCP (for example a veterinary student, a technician). Approved identifiers are required on sheep being genotyped and the official identification number (15 digits) included with the sample submission

Figure 23 Photos of jugular venipuncture in sheep

Jugular venipuncture

To facilitate the rapid collection of blood samples from multiple sheep in as little time as possible, it is suggested to not waste time upending the sheep. Restrain sheep for venipuncture in a standing position.

Occlude thoracic inlet, palpate or approximate the location of the jugular vein, and insert Vacutainer needle.

A single-use needle is required for each animal, to prevent cross-contamination of DNA.

Collect a full 7-10 ml of blood in an ethylenediaminetetraacetate (EDTA) tube (lilac or purple top).

Make sure that the sample and individual animal identification are irrefutably connected.

Samples should be stored at 4°C until shipped. Ship to laboratory as soon as possible.

Check with individual laboratories for preferences regarding sample submission, including preferred day of submission.

Tissue samples for genotyping

Other tissues such as brain and hair can be used. Check with individual laboratories for preferences regarding tissue selection. If the head or brain sample is being forwarded for scrapie testing, it would be easiest for the laboratory to forward a sample of brain for genotyping.

Appendix D: RAMALT biopsy sampling procedures

The recto-anal mucosal-associated lymphoid tissue (RAMALT) biopsy procedure is performed on sheep and goats and is a live animal screening test. Another live animal screening test is the third eyelid lymphoid follicle sampling procedure used in sheep but is more difficult and less commonly used.

As potentially infective lymphoid tissue is being harvested, and as the site of harvesting (recto-anal tissue) is theoretically a possible route of introduction of the scrapie agent, precautions to prevent potential transmission of scrapie are required in sampling potential source flocks.

Instruments can be handled in one of the following ways:

Technique

One person is required to restrain the animal by holding it against a wall or in a corner.

Verify the individual identification of the animal. For sheep, also verify by checking individual identification that this animal has been genotyped as a 171QQ.

Anesthetic/analgesic cream (lidocaine and prilocaine) is not required but if preferred can be applied to the distal rectal mucosa with a gloved finger. An example would be Eutectic Mixture of Local Anesthetics (EMLA), a 1:1 oil/water emulsion of a eutectic mixture of lidocaine and prilocaine based cream, produced by Astrazeneca Canada Inc. Lidocaine and prilocaine, both solids at room temperature, form a eutectic that is an oil with a 16°C melting point.

If using a rectal speculum, insert into rectum after liberal application of analgesic cream, which also doubles as a lubricant.

Allow approximately five minutes for the analgesic/anaesthetic cream to take effect.

Figure 24 Photo of inserting the speculum into the rectum

Palpate/visualize the recto-anal junction. Take samples approx 1-2 cm anterior (aboral) to the recto-anal junction. Preferred locations for sampling include the dorsolateral (10 and 2 o'clock positions) and ventrolateral (4 and 8 o'clock positions) surfaces of the mucosa. Take samples at 10, 2 and, if necessary, 4 and 8 o'clock positions. Avoid sampling the roof or the floor of the mucosa (the 6 and 12 o'clock positions). Using forceps, pick up the rectal mucosa/crypt, creating a "tent" of tissue. Using scissors, excise the tent of tissue.

Figure 25 Photos of taking rectal mucosa biopsies

Figure 26 Photo of taking rectal mucosa biopsies

Place the biopsy samples in a labelled cassette lined with a biopsy pad (for example Leica Microsystems – 1 x 1.25 Cat # 3801000).

Figure 27 – Photo of an example of a biopsy cassette with biopsy pad

Figure 28 – Photo of placing rectal mucosa biopsy into the biopsy cassette

Place the cassette(s) in a leak-proof container with 10% neutral buffered formalin for the fixation period (see notes below), at a ratio of 1:10 tissue/formalin, prior to shipping. Send the sample(s) to an approved laboratory for RAMALT biopsy testing using immunohistochemistry.

Notes:

Appendix E: sanitary precautions/disinfectants

Scrapie is not considered to be a human pathogen; however, when sampling, normal sanitary precautions against a possible range of pathogens should be taken. Wear protective clothing, gloves and face protection when collecting brain and lymph node specimens. Always avoid direct contact with brain and lymphoid tissues. Personnel at tissue harvesting sites should take precautions to avoid ingestion of the agent.

Prion agents are particularly resistant to standard physical and chemical methods of decontamination. Traditional disinfectants such as Virkon are not effective against prion agents. Instruments and surfaces must be disinfected with either sodium hypochlorite or sodium hydroxide, recommended protocols include the following:

It is recommended that the animal's head be placed on a disposable plastic drop sheet. The sheet should be large enough to cover the work area. Used disposable protective clothing, gloves, and animal remains should be buried or incinerated.

Instruments

Instruments and materials subject to re-use should be kept moist between the time of exposure to infectious materials and subsequent cleaning and decontamination.

Surfaces:

Chemicals

Appendix F: cleaning and disinfection on a premises

Cleaning and Disinfection (C&D) on a premises is applicable in certain situations when a SFCP flock/herd with status D or higher is moving to a new premises and wishes to keep that status. If C&D is required, owners who do not undertake C&D and have it approved will not be permitted to keep their flock status. Details are provided in the SFCP National Standards Section 2.

If C&D is required on the premises it must be supervised by the accredited veterinarian and follow an approved cleaning disinfection protocol as follows:

Appendix G: list of laboratories

CFIA-approved laboratories for scrapie genotyping

Animal Health Laboratory
Laboratory Services Division
University of Guelph
419 Gordon Street, Building 89
P.O. Box 3612
Guelph, Ontario, N1H 6R8
Telephone: 519-824-4120, ext. 54530
Facsimile: 519-827-0961

USDA Laboratories - PDF (7 kb)
Laboratories approved by the United States Department of Agriculture (USDA) for scrapie genotyping are acceptable to the CFIA Terrestrial Animal Health Division for export and flock certification testing. The current list of USDA-approved labs for scrapie genotyping can be found on the USDA Animal and Plant Health Inspection Service website under Approved Genotyping Laboratories.

CFIA-approved laboratories for scrapie testing using the BioRad ELISA

Alberta Agriculture and Forestry
Agri-Food Laboratories Branch
TSE Laboratory
6909 - 116th Street
Edmonton, Alberta, T6H 4P2
Telephone: 780-422-4830
Facsimile: 780-415-4527

Animal Health Laboratory
Laboratory Services Division
University of Guelph
419 Gordon Street, Building 89
P.O. Box 3612
Guelph, Ontario, N1H 6R8
Telephone: 519-824-4120, ext. 54530
Facsimile: 519-827-0961

Prairie Diagnostic Services Inc.
52 Campus Drive
Saskatoon, Saskatchewan, S7N 5B4
Telephone: 306-966-7316

Ministère de l'Agriculture des Pêcheries et de l'Alimentation du Québec (MAPAQ) (French only)
Laboratoire d'épidémiosurveillance animale du Québec
3220 Sicotte Street
Saint-Hyacinthe, Quebec, J2S 7X9
Telephone: 450-778-6542
Facsimile: 450-778-6535

Note: Samples may also be submitted through a CFIA district office to CFIA laboratories in Ottawa (Fallowfield), Lethbridge, or Saint-Hyacinthe as part of the National Scrapie Surveillance Program.

CFIA-approved laboratories for RAMALT biopsy testing using immunohistochemistry

The CFIA Ottawa Laboratory (Fallowfield) is currently the only laboratory conducting the immunohistochemistry (IHC) test. Samples must be submitted through a CFIA district office to the CFIA laboratory in Ottawa (Fallowfield). Samples must be sent to the district office within 2 days of fixation. Contact your district office to plan the shipment and for more information.

Date modified: