7. Voluntary Scrapie Flock Certification Program

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

1. While the precise cause of the disease is still a subject of significant research, abnormal prion protein is associated with the presence of disease.

Susceptible Species

2. Scrapie is a naturally occurring disease of domestic and wild (mouflon) sheep and goats.

Distribution

3. The disease was first reported in sheep over 250 years ago and in Canada in 1938. Scrapie is currently recognized in many sheep-raising countries. New Zealand and Australia are notable as countries recognized free from the disease.

Epidemiology

4. Pregnancy appears to trigger the migration of abnormal prion protein to the reproductive tract. Birthing fluids and tissues, such as placenta, from infected females contain large quantities of the scrapie agent. Healthy animals become infected by eating or licking contaminated materials in the lambing or kidding environment. Newborn lambs and kids sharing the same contaminated environment (lambing pen) are extremely susceptible to infection. Adult females sharing the same environment are also at risk. Although scrapie is an infectious disease, it is not highly contagious. In contrast to some diseases such as foot-and-mouth, casual contact between animals and inanimate objects (such as vehicle tires), people or the wind is not known to transmit scrapie.

Abnormal prion proteins are extremely resilient to traditional approaches to disinfection, being 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 periods of years. Reports from Iceland have suggested that environmental contamination or hay mites acting as mechanical vectors have resulted in the reintroduction of scrapie. This phenomenon has not been an epidemiological observation in North America.

Several separate research studies on the potential of scrapie transmission by embryos have produced conflicting results. At present, there is inadequate information, other than that pertaining to genetics, to negate embryo transfer or to provide advice on appropriate measures to mitigate the risk of scrapie transmission from an embryo of unknown genotype. There is no evidence to date that implicates semen in the transmission of scrapie.

Genetic Effects

Genetic makeup has been determined to be a significant factor in a sheep's susceptibility to infection with scrapie. At this time, a correlation between specific genetics and related scrapie susceptibility has not been determined for goats. Current experimental evidence indicates that there are different forms of the sheep prion proteins. 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 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 prion protein undergoing the structural change associated with scrapie in North America. The presence of glutamine (Q) or histidine (H – treated the same as a Q) at codon 171 results in the prion protein being susceptible to the structural change associated with North American scrapie. An alanine (A) at codon 136 confers resistance to the prion protein undergoing the structural change associated with North American scrapie. The presence of valine (V) at codon 136 can produce susceptibility to structural change associated with North American scrapie. 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:

Most susceptible 171 QQ > 136 AV 171 QR > 136 AA 171 QR > 171 RR Greatest resistance

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

The specific amino acids and the sites that appear to confer susceptibility versus resistance vary with the strain of scrapie agent involved and the breed of sheep. Research indicates that QQ sheep are the most susceptible to scrapie infection. QR sheep are much less susceptible and RR sheep appear to be resistant. While the genetic profile for all sheep breeds present in North America has not been determined, the vast majority of positive cases of scrapie that have been genotyped in North America have been determined to be homozygotes for glutamine (QQ) at codon 171. Small numbers of QRs around the world have tested positive for scrapie. In these cases, the amino acids at a second codon (136) are examined and heterozygotes for alanine and valine at codon 136 appear to indicate greater susceptibility among the QR population. Recent reports show a handful of RR positive scrapie cases; details regarding these cases are not currently available.

Recent science indicates that the genotype of the fetus may influence the migration and accumulation of abnormal prion in the placenta of an infected ewe. A 171 QQ infected ewe carrying a 171 QQ fetus would result in the accumulation of large quantities of abnormal prion, which is then shed during birth or abortion. The abnormal prion does not accumulate to a significant degree in the placenta of a fetus with a genotype 171 QR or 171 RR. This means that use of a 171 RR 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 171 QQ sheep does not automatically have scrapie, just as it is not an absolute guarantee that a 171 RR sheep cannot get scrapie. The CFIA has no intention of mandating the Canadian sheep flock to breed for scrapie resistance. 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 based on individual factors such as breed, the prevalence of 171 RR within the flock, the management of the ewe flock, and the current status of other breeding indices.

Clinical Signs

5. Clinical signs of scrapie rarely develop before the age of 18 months and are highly variable. The majority of cases are diagnosed in animals two to five years of age. As many animals do not show overt clinical signs until late in the course of the disease, significant transmission of the scrapie agent occurs prior to any visible indications of a disease problem. Clinical signs vary considerably, with wasting and debility with or without tremors and a lack of coordination being more prominent features throughout the clinical course of cases of scrapie in Canada.

When present, the predominant nervous signs of scrapie are as follows:

• tremors and a lack of coordination;
• a change in mental status (apprehension, teeth grinding, and aggression); and
• altered sensation (pruritus or itchiness, loss of wool, excoriation and inflammation of the skin, nibble reflex, and excessive licking).

Differential Diagnosis

Differential diagnosis to consider in the initial clinical stages of scrapie includes the following:

• ectoparasites (lice, mites)
• hypomagnesaemia
• pregnancy toxemia (ovine ketosis)
• rabies
• listeriosis
• maedi-visna
• pseudorabies (Aujeszky's disease)
• sarcocystosis

Laboratory Diagnosis

6. Scrapie is diagnosed through the detection of the abnormal prion protein in brain or lymphoid tissue. Tissues to submit for diagnosis include the following: obex of brain or retro-pharyngeal lymph nodes (post-mortem); third eyelid or recto-anal mucosa associated lymphoid tissue (RAMALT) (in a live animal). Tissues are sent fixed in formalin and/or fresh frozen depending on the test being applied for surveillance cases and the laboratory preference. Various testing techniques may be applied to the tissue; however, immunohistochemistry is the current gold standard testing technology for use on suspect cases. Abnormal prion protein is detectable in very young animals (at eight months), but detection is generally more consistent in animals over 12 months of age.

Detection of abnormal prions in third eyelid or RAMALT tests has high specificity; however, false negatives (third eyelid or RAMALT negative, brain positive animals) are found. To maximize sensitivity, third eyelid testing should be applied to ewes over 14 months of age with the genotype 171 QQ. Similarly, RAMALT testing should be applied to ewes over 12 months of age with the genotype 171 QQ, and does over 12 months of age. Lymphoid tissue testing is a useful screening tool for the presence of infection in a flock, but it is not a reliable indicator of individual freedom from disease.

Genotyping 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

7. No immune response to scrapie prion protein has been detected.

Public Health

8. Scrapie is not known to be a human health hazard.

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7.2 Policy and Principles of Control

Policy Statement

1. The Canadian Voluntary Scrapie Flock Certification Program (VSFCP) is a program which producers can choose to join or not. However, once they are participating in the program, their compliance with the National Standards is mandatory.

The objective of the VSFCP is to provide owners with the opportunity to have their flocks/herds identified as negligible risk with respect to scrapie. Being a member and reaching certified status in the program provides assurances to potential purchasers that the animal for sale is coming from a negligible risk flock/herd. Export certification of scrapie status for countries with higher zoosanitary requirements for scrapie may be based on enrolment and activities under the VSFCP. This program also provides a valuable vehicle for surveillance for scrapie within Canada. Any owner of sheep or goat premises who agrees to comply with the VSFCP may enrol.

Statutory Authority

2. Scrapie is a reportable disease under the Reportable Diseases Regulations, prescribed pursuant to 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.

3. The primary role of the federal government in the VSFCP is to establish the national standards (as detailed in module 7.9 Appendix 3) and to enforce compliance with these standards.

Principles for Control and Eradication

4. 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. Some of these tools have not been established in goats; thus, the only approach to ascertaining the scrapie status in goats is ongoing herd surveillance. This can be achieved by post-mortem testing, RAMALT testing, the absence of clinical signs, and the prevention of exposure to scrapie over a designated period of time.

The scrapie prion may persist in the environment for several years and may be transmitted to live animals by an infected premises. Therefore, in rare instances where an owner will be starting a new flock/herd with animals acquired from a flock/herd already in the VSFCP, and intends to keep that status, the owner will need to attest to whether or not (or if unknown) the enrolling premises has contained small ruminants within the last 10 years. This step will take place during the initial application process, so that the appropriate actions can be taken, prior to stocking animals on the premises.

There are three different approaches or pathways to follow for a sheep flock to achieve certification status. As with goats, surveillance of mature animals that die, the absence of clinical signs, and the prevention of exposure to scrapie over a designated period of time constitute the first pathway. A second pathway screens the flock for the presence of scrapie by taking lymphoid follicle samples from the third eyelid, or recto-anal mucosae from the most genetically susceptible ewes, and testing the samples for scrapie, followed by commencing surveillance of mature animals that die, and preventing exposure to scrapie. The final pathway to certification requires the selection for genetic resistance for scrapie followed by ongoing surveillance of mature animals that die.

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

A scrapie positive animal is any animal in which the CFIA confirms the diagnosis of scrapie by applying the current gold standard test to lymphoid or brain tissues. The current gold standard test is immunohistochemistry.

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7.3 Accredited Veterinarian's Responsibilities

Preliminary Activities

1. Obtain and read the terms and conditions for a flock/herd to participate in the VSFCP. (See module 7.9 Appendix 3.)

2. Obtain training and establish an accreditation agreement with your local CFIA district veterinarian.

3. The producer should be advised to contact the VSFCP regional administrator, the Canadian Sheep Federation (CSF), to obtain an application form and the requirements to participate, advance and maintain certification within each of the three pathways to certification.

4. The accredited veterinarian and the owner should discuss whether they intend to enrol a new or established herd. If it is a new herd, sourcing of animals will require discussion prior to application. If it is sourced from a herd enrolled on the VSFCP and the owner intends to keep that status, it will be necessary to include a letter with the application package attesting to whether or not (or if it is unknown) small ruminants have been contained on the enrolling premises within the last 10 years. It would then be necessary to take the appropriate actions prior to any stocking/ordering of small ruminants.

5. The accredited veterinarian and owner should discuss which of the three pathways to certification they intend to pursue. Assessment of the facilities, flock/herd management and record-keeping on premises should be done to gauge the degree to which the accredited veterinarian feels the producer can be successful, and to identify any changes in record keeping or management that would be necessary in order to facilitate the fulfilment of VSFCP requirements.

General Overview of Responsibilities

6. Accredited veterinarians under this program are responsible for the following:

• reviewing the requirements of the program and responding to the questions of those premises owners applying for or enrolled in the program;
• teaching the owner to recognize the clinical signs of scrapie, providing information on the epidemiology of the disease, and guiding flock/herd management;
• assessing the facilities, flock/herd management and record-keeping on the premises proposed for membership in the program;
• assessing the health of the flock/herd to determine whether any animal (sheep or goat) is demonstrating signs of scrapie;
• reporting any suspected case of scrapie to the CFIA district veterinarian;
• supervising the flock/herd inventory;
• reconciling records to ensure that the flock/herd meets the program requirements (especially with regards to purchased animals);
• signing and submitting reports, including the annual inventory to the status assessor;
• collecting and submitting blood samples (for genotyping), collecting and submitting third eyelid or recto-anal mucosa lymphoid follicle samples, and sampling and submitting brain samples if the owner requests assistance (or teaching the brain and mandibular lymph node sampling technique to the owner);
• reporting any discrepancies between the program pathway requirements and the occurrences on the premises under the accredited veterinarian's supervision to the status assessor (CSF);
• identifying structures on a premises that may have been used to feed, water, contain or birth small ruminants;
• being familiar with prionicidal agents and the correct concentration to which they must be made; and
• supervising and approving appropriate cleaning and disinfection of a premises.

Producer Responsibilities

7. It is the owner's responsibility to comply with the requirements of the selected pathway of the VSFCP. (See module 7.9 Appendix 3.)

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7.4 Procedures Common to All Pathways

Preliminary Activities

1. Obtain and read the National Standards for the VSFCP.

2. Schedule a meeting with the local CFIA district veterinarian to review the terms and conditions for flock/herd certification and to discuss the accredited veterinarian's duties and the procedures that must be followed under the selected pathway. A tutorial or a review of the transmissible spongiform encephalopathy (TSE) brain sampling technique in small ruminants is suggested at this time.

3. Establish a valid accreditation agreement (contract) with the CFIA district office for the delivery of the VSFCP.

4. Discuss with owners whether they intend to enrol a new or an established herd. For a new herd, discuss the sourcing of animals prior to application. If the animals are sourced from a herd enrolled on the VSFCP and the owner intends to keep that status, include a letter with the application package, attesting whether or not (or if unknown) small ruminants have been contained on the enrolling premises within the last 10 years. Take the appropriate actions prior to the stocking and/or ordering of small ruminants. (The flowchart down below illustrates the various options for enrolling new herds.)

5. Discuss with the owner which of the three pathways to certification they intend to pursue. Assessment of their facilities, flock/herd management and record keeping practices should be undertaken to gauge the degree to which the accredited veterinarian feels the producer can be successful, and to identify any changes in record-keeping or management that would be necessary to facilitate the fulfilment of VSFCP requirements.

6. Advise the owner to contact the regional administrator, CSF, to obtain an application form and to learn the requirements to participate in, advance and maintain certification within each of the three pathways to certification.

Application

7. The flock/herd owner contacts the regional administrator (CSF) and requests an application form.

8. An application 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 form must be accompanied by the following:

• a site plan of all buildings and grazing premises to which the animals are given access;
• the initial flock/herd inventory prepared by the accredited veterinarian within the three-month period immediately prior to the submission of the application;
• a record-keeping plan (objective: records must be reviewed completely and effectively at each annual inspection); and
• if the producer is starting a new flock/herd with small ruminants from level D of the VSFCP or higher, and intends to keep this status, they must include a letter indicating the status of the enrolling premises with respect to small ruminants over the last 10 years.

9. The application and inventory must be signed by the accredited veterinarian and the producer.

10. The step of applying to the regional administrator (CSF) for entry into the VSFCP is delayed in pathways two and three until other conditions are met.

Anniversary Quarter

11. The flock/herd category is effective from the date when the flock/herd is accepted into 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).

Inventories

12. Supervise the initial animal inventory. All sheep and goats 12 months or older on the premises must bear two forms of identification. All animals aged less than 12 months must be officially identified when a change in ownership occurs or when animals are moved from their usual location (e.g. exhibition, insemination centre, sales barn or auction barn).

13. Assess the animals for any clinical evidence of scrapie.

14. Instruct the owner to record all additions to the flock/herd. Records are required for every sheep or goat that is born on, or enters the premises.

15. Inform the owner that acquisitions of live sheep or goats or embryos must include documentation required by the specific pathway.

16. Instruct the owner to maintain appropriate documentation of every sheep or goat that leaves the flock/herd (e.g. sales receipts, notation of deaths).

17. Inform the owner that records must be maintained for a period of five years.

Annual Physical Inspection

18. The accredited veterinarian must visit the enrolled premises at least once a year. The annual physical flock/herd inventories must be conducted under the supervision of the accredited veterinarian. Appropriately trained third-party personnel, such as animal health technicians or veterinary students, may participate. The inventory will identify every sheep and goat on the premises. During the inventory inspection, all animals over 12 months of age in the flock/herd must be identified individually (individual ID read) and assessed for any clinical symptoms of scrapie.

Annual Inventory

19. The annual inventory report is the responsibility of the accredited veterinarian. The foundation of the annual inventory report is the reconciliation of this year's annual inventory with the previous year's annual inventory. The annual report lists the following:

• all identification of each sheep and goat on the premises at the time of the inventory;
• all identification devices placed on each sheep or goat, including the current lamb (or kid) crop and any sheep or goat that has lost its identification device;
• all sheep or goats that have entered or left the premises since the last inventory;
• the status of the flock of origin for sheep or goats entering the premises as live animals or implanted embryos;
• all deaths;
• the destination of every sheep or goat that moved off the premises as established by a bill of sale or, if the animal has not been sold, a signed document showing the destination of the sheep or goat; and
• appropriate laboratory results (scrapie testing).

When you are satisfied that the report adequately documents all reconciliation of the inventory, sign the report.

20. Forward the document to the status assessor within the anniversary quarter in which the enrolled flock/herd was registered in the program.

21. Instruct the owner to submit an application to the regional administrator to advance to the next level of the certification program or to maintain certified status once they have attained that level.

Deadstock Testing

22. Every sheep or goat over 12 months of age that dies on the premises must be submitted for scrapie testing at a CFIA approved laboratory. This is the most critical element of the program and the absence of even one submission without documented cause will jeopardize the status of the flock/herd within the program. The nearest approved laboratory for scrapie surveillance testing should be identified by both the accredited veterinarian and the producer. The producer may submit the head or brain sample directly to the laboratory. The accredited veterinarian should review how to sever the head and indicate that samples should be stored frozen. Heads/samples may be held and sent, or delivered in batches. If the owner kills a mature sheep for humane purposes, testing is still required. When the brain is too damaged, one head lymph node should be submitted for diagnoses (i.e. the retropharyngeal, mandibular or third eyelid).

23. Flocks/herds that are working through status levels E to A must submit all animals more than 12 months of age that die on farm for scrapie testing. Upon obtaining certified status, the owner may continue to submit all animals more than 12 months of age that die on farm for scrapie testing or, alternatively, they may submit for scrapie testing 80% of animals more than 12 months of age that die and 20% of the animals of the flock more that 12 months of age that are slaughtered.

24. Animals older than 12 months submitted for routine post-mortem examination may be considered as dead submissions if tested for scrapie.

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

26. If unsuitable brain specimens are received by a laboratory, the laboratory will notify the status assessor and the 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/status assessor. If negligence on the part of the producer is identified as the cause, or this occurrence is repeated, the program's requirements will be considered to have been unmet and the status of the flock/herd will be suspended.

Sick Animals

27. Instruct the owner of the premises to report illness in a sheep or goat over 12 months of age lasting longer than two weeks, with the exception of a physical injury. 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. Educate the owner to recognize the clinical signs of scrapie and provide information on the epidemiology of the disease.

Cleaning and Disinfection (C&D) (if applicable)

28. C&D applies to structures where small ruminants are identified to have been contained (indoors or outdoors), or birthed. Bury or compost bedding, manure, and waste material from these lambing/kidding/housing areas for six months and then dispose of the material on land to which sheep and goats do not have access.

Scrape off surface soil (1-2 inches below the depth to which the surface is broken up) from areas identified as outdoor lambing/kidding or housing areas, and bury or dispose of the soil on land to which sheep and goats do not have access.

Remove organic debris from, then superficially disinfect concrete, metal, and wooden structures, including water troughs and drinking bowls, identified to have been in contact with small ruminants. Use sodium hypochlorite solution (at a concentration of 2% available chlorine) or sodium hydroxide (NaOH at a concentration of 2 Molar). (See module 7.9 Appendix 2.)

29. It is suggested that the accredited flock/herd veterinarian approve the cleaning before proceeding with the disinfection. This course of action permits the cleaning to be repeated, if it proves inadequate, without having to repeat the more difficult and dangerous disinfection step.

30. Owners who do not undertake C&D and have it approved will not be permitted to assume the higher flock status.

Click on image for larger view

Flowchart: New Herd Enrolling on VSFCP (Voluntary Scrapie Flock Certification Program)

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7.5 Pathway One: Limited Acquisitions Plus Surveillance

General Information

1. This pathway is available to goats and sheep.

2. Advise the producer that at the current time, pathway one is the only pathway of the Canadian VSFCP recognized by the United States Department of Agriculture (USDA), although this may change in the near future. To maintain this recognition, flocks/herds on pathway one can not access animals following certification in pathways two and three.

3. All requirements detailed in module 7.4 Procedures Common to All Pathways are applicable to flocks/herds participating in this pathway.

Acquisitions

4. Instruct owners that acquisitions of live female sheep or goats and embryos must be accompanied by documentation of the certification level and enrolment date of the flock/herd from which they are sourced or purchased. Explain to the owner that the impact of acquiring female animals or embryos from a flock or herd of a lower certification level will be the downgrading of their own flock/herd's level or anniversary quarter. If uncertain of the certification level of a particular Canadian flock or of the equivalence of another country's program, the accredited veterinarian or producer may obtain this information from the regional administrator (CSF), or the CFIA.

Advancement

5. The program includes six levels, from the entry level (level E) to the highest level (certified). A minimum of five years (one year at each of level E, D, C, B, and A) is necessary for a registered flock to reach the certified level. Once a flock has reached the certified level, it maintains this level provided that the applicable requirements continue to be met.

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7.6 Pathway Two:
2A – Third Eyelid Screening Plus Surveillance
2B – RAMALT Biopsy Screening Plus Surveillance

Pathway 2A – Third Eyelid

General Information

1. This pathway is only available to sheep; it is not available to goats.

2. Advise the producer that at the current time, this pathway to certification is not recognized by the USDA, although this situation may change in the near future.

3. All requirements detailed in module 7.4 Procedures Common to All Pathways are applicable to flocks participating in this pathway

Pre-Application

4. The accredited veterinarian must supervise the collection of appropriate samples for genotyping (module 7.9 Appendix 1B) from all ewes older than 14 months. Care must be taken not to contaminate the samples with DNA from other animals. The samples are submitted to a laboratory recognized by the CFIA for scrapie genotyping.

5. When the results of the genetic screening are available, all ewes that are determined to have the 171 QQ genotype are to have a sample of lymphoid tissue collected from the third eyelid by the accredited veterinarian (module 7.9 Appendix 1C). A minimum of 50 ewes must be tested to continue in this pathway. Instruments that come into contact with lymphoid tissues should be handled appropriately regarding potential prion contamination and transmission (modules 7.9 Appendix 1C and 7.9 Appendix 2).

6. If any laboratory test for scrapie is positive, the accredited veterinarian is to contact the CFIA district veterinarian. The positive animal will be ordered destroyed and confirmatory testing will be conducted on a brain sample.

Application

7. If all laboratory tests for scrapie are negative, the owner must submit an application for enrolment into level B of the VSFCP, with all of the documentation detailed in module 7.4 Procedures Common to All Pathways.

8. Compliance with all procedures documented in module 7.4 Procedures Common to All Pathways is required upon acceptance into the program.

Acquisitions

9. Acquisitions of live sheep or embryos must include documentation pertaining to the certification level and enrolment date of the flock/herd from which they were sourced or purchased. Advise the owner that the impact of acquiring stock or embryo from a lower-level flock will be the downgrading of their own flock level or anniversary quarter. If uncertain of the certification level of a particular Canadian flock or of the equivalence of another country's program, the accredited veterinarian or producer may obtain this information from the CSF or the CFIA.

Advancement

10. To apply to advance to level A, any breeding females which were purchased from other farms prior to entering the VSFCP but which were not 14 months or older (and thus did not have a third eyelid test) at the time of the first testing must now be subject to genotyping and third eyelid testing as set out at points 4 and 5 above. These results must be submitted along with the annual report and the request to advance to level A.

11. After a minimum of 12 months at level A, the producer may apply to advance to the certified level. Once a flock has reached the certified level, it maintains this level provided that the applicable requirements continue to be met.

Pathway 2B – RAMALT Biopsy

General Information

12. This pathway is available to sheep and goats; but point 15 below does not apply to goats.

13. Advise the producer that at the current time, this pathway to certification is not recognized by the USDA, although this situation may change in the near future.

14. All requirements detailed in module 7.4 Procedures Common to All Pathways are applicable to flocks/herds participating in this pathway.

Pre-Application

15. The accredited veterinarian must supervise the collection of appropriate samples for genotyping (module 7.9 Appendix 1B) from all ewes older than 12 months. Care must be taken not to contaminate the samples with DNA from other animals. The samples are submitted to a laboratory recognized by the CFIA for scrapie genotyping.

16. When the results of the genetic screening are available, all ewes that are determined to have the 171 QQ genotype are to have a RAMALT biopsy collected by the accredited veterinarian (module 7.9 Appendix 1D). In a goat herd, genotyping does not apply, but all does 12 months of age or older must have a RAMALT biopsy collected. A minimum of 50 ewes/does must be tested to continue in this pathway. Instruments that come into contact with lymphoid tissues should be handled appropriately regarding potential prion contamination and transmission (modules 7.9 Appendix 1D and 7.9 Appendix 2).

17. If any laboratory test for scrapie is positive, the accredited veterinarian is to contact the CFIA district veterinarian. The positive animal will be ordered destroyed and confirmatory testing will be conducted on a brain sample.

Application

18. If all laboratory tests for scrapie are negative, the owner must submit an application for enrolment into level B of the VSFCP, with all documentation detailed in module 7.4 Procedures Common to All Pathways.

19. Compliance with all procedures documented in module 7.4 Procedures Common to All Pathways is required upon acceptance into the program.

Acquisitions

20. Acquisitions of live sheep, goats or embryos must include documentation pertaining to the certification level and enrolment date of the flock/herd from which they were sourced or purchased. Advise the owner that the impact of acquiring stock/embryo from a lower-level flock/herd will be the downgrading of their own flock/herd's level or anniversary quarter. If uncertain of the certification level of a particular Canadian flock or of the equivalence of another country's program, the accredited veterinarian or producer may obtain this information from the CSF or the CFIA.

Advancement

21. To apply to advance to level A, any breeding females which were purchased from other farms prior to entering the VSFCP but which were not 12 months or older (and thus did not have a RAMALT biopsy test) at the time of the first testing, must now be subject to genotyping (if ewes) and RAMALT biopsy testing as set out at points 15 and 16 above. These results must be submitted along with the annual report and the request to advance to level A.

22. After a minimum of 12 months at level A, the producer may apply to advance to the certified level. Once a flock has reached the certified level, it maintains this level provided that the applicable requirements continue to be met.

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7.7 Pathway Three: Genetic Selection

General Information

1. This pathway is only available to sheep; it is not available to goats.

2. Advise the producer that, at the current time, this pathway to certification is not recognized by the USDA, although this situation may change in the near future.

3. All requirements detailed in 7.4 Procedures Common to All Pathways are applicable to flocks participating in this pathway.

Assist Producer in Pathway Choice

4. The accredited veterinarian is advised to assist the producer in the decision whether or not to use genetic selection for scrapie resistance, and if so, whether to only genotype rams and pursue selective breeding for resistance, using 171 RR rams exclusively; or genotype all breeding stock to access the 171 RR available in both the rams and the ewes. This may be an iterative process of testing and decision making. The producer may undertake to test only breeding rams at first. With these results, it may be possible to determine whether there is a sufficient base of genetic resistance to scrapie to start a breeding program for scrapie resistance without substantial loss of other production traits, using only 171 RR rams. If there is an insufficient base of genetic resistance in the ram population, the producer may undertake to test the rest of the breeding flock. These results may then be reviewed to determine if there is a sufficient base of genetic resistance across the ewes and rams to breed for resistance to scrapie without substantial loss of other production traits.

Genotype Laboratory Testing

5. A veterinarian accredited to deliver the VSFCP must supervise the collection of appropriate samples for genetic testing (module 7.9 Appendix 1B). The samples must be genotyped at a laboratory recognized by the CFIA for such purposes (module 7.9 Appendix 1E). Samples from 171 RR rams must have the genotype confirmed by a second laboratory. (Only one of the two laboratories has to be recognized by the CFIA for genotype testing.) The cost of this verification may be minimized by requesting that the first laboratory forward only the extracted DNA to the second lab.

Whole-Flock Approach — Application

6. When scrapie genetic testing results document that all breeding animals are either 171 RR or 171 QR, the owner must submit an application for enrollment into level A of the VSFCP, with all documentation detailed in module 7.4.

7. Compliance with all procedures documented in module 7.4 is required upon acceptance into the program.

Whole-Flock Approach — Acquisitions

8. Natural increases (home-grown replacements): Lambs born from a mating involving at least one 171 RR parent may be kept and used as breeding stock without requiring a genotype test.

9. Natural increases (home-grown replacements): Lambs born from a mating not involving at least one 171 RR parent must be genotyped if retained as breeding stock. Only 171 RR or 171 QR animals may be retained as breeding stock. Animals from non-RR matings that are not genotyped must be removed from the flock by 12 months of age. If one of these animals is accidentally bred with lambs on the premises, the flock status will be suspended, pending investigation.

10. Acquired replacement breeding stock (purchases/loans): Newly acquired breeding stock must be genotyped as 171 RR or 171 QR by a laboratory recognized by the CFIA for that purpose (module 7.9 Appendix 1E). Semen must be sourced from a ram genotyped as 171 RR or 171 QR by a laboratory recognized by the CFIA for that purpose (module 7.9 Appendix 1E).

Whole-Flock Approach — Advancement

11. After 12 months at level A, the producer may apply to advance to the certified level. Once a flock has reached the certified level, it maintains this level, provided that the applicable requirements continue to be met.

Rams-Only Approach — Preapplication

12. Following the producer's decision to pursue the rams-only approach to selection for genetic resistance to scrapie, it will probably take a number of years of ram testing, selection, breeding, and culling to assemble an entire flock that can be documented to be offspring from resistant rams. Through this period, the accredited veterinarian's role will be limited to sampling of the rams for genotyping.

13. Once the producer can document through breeding records that all remaining animals are offspring of a ram genotyped 171 RR, the owner must submit an application for enrollment into level A of the VSFCP, with all of the documentation detailed in module 7.4.

14. Compliance with all procedures documented in module 7.4 is required upon acceptance into the program.

Rams-Only Approach — Acquisitions

15. Acquired replacement breeding stock (purchases/loans): Newly acquired breeding rams must be genotyped as 171 RR by a laboratory recognized by the CFIA for that purpose (module 7.9 Appendix 1E). Semen must be sourced from a ram genotyped as 171RR by a laboratory recognized by the CFIA for that purpose (module 7.9 Appendix 1E). Purchased breeding ewes or embryos must be genotyped as 171 RR or 171 QR by a laboratory recognized by the CFIA for that purpose (module 7.9 Appendix 1E).

Rams-Only Approach — Advancement

16. After 12 months at level A, the producer may apply to advance to the certified level. Once a flock has reached the certified level, it maintains this level, provided that the applicable requirements continue to be met.

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7.8 Export Certification

1. Animals from flocks/herds enrolled in the VSFCP may be certified and endorsed by the CFIA as participating in a program which 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 flock certification program are obtained from the regional administrator, CSF.

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