Chronic wasting disease of deer and elk

Chronic wasting disease (CWD) is a prion disease that affects cervids such as deer, moose, elk and reindeer. It is a progressive, fatal disease of the central nervous system (the brain and the spinal cord) of cervids. Learn how to recognize the disease, protect cervids and what we're doing to keep Canadians safe.

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The disease in Canada

CWD was discovered in 1967. This disease has been found in farmed and wild cervids in Canada and the United States. It has also been found in farmed cervids in South Korea and in wild cervids in Norway, Finland and Sweden.

In Canada, CWD was first detected in farmed cervids on a Saskatchewan elk farm in 1996. The disease has since been mainly found in Alberta and Saskatchewan in farmed deer and elk as well as in wild deer, elk and moose. The disease has also been detected in 1 red deer farm in Quebec and wild deer in British Columbia and Manitoba.

CWD has not been found in wild caribou anywhere in North America.

Map: Distribution of Chronic Wasting Disease in North America (English only)

Confirmed cases

Reporting the disease

CWD is a reportable disease under the Health of Animals Act.

This means that, by law, all animals infected or suspected of being infected with CWD must be reported to a Canadian Food Inspection Agency (CFIA) district veterinarian.

To report a suspected or known case of CWD, contact your local CFIA animal health office.

Signs of the disease

  • Depression (reduced activity levels)
  • Difficulty swallowing
  • Excess salivation
  • Excessive urination
  • Increased thirst
  • Lack of coordination
  • Paralysis
  • Pneumonia (difficulty breathing)
  • Separation from the other animals in the herd
  • Unusual behaviour
  • Weight loss

Onset of signs

Cervids with CWD may show many different signs as the disease slowly damages their brain. Signs can last for weeks to months before the animal dies. Some animals may not show any clinical signs. Animals that appear clinically healthy may be infected.

Some infected animals may appear healthy until their sudden death and others may not show signs until late stages of disease.

Animals are usually 3 to 4 years old before clinical signs appear, but signs have been seen in animals as young as 15 months or as old as 13 years.


CWD spreads by direct contact between animals or from a contaminated environment to an animal. For example, the soil and vegetation can become contaminated by urine, feces or by the carcass of a dead animal.

Prions can remain infectious in the environment for years after an infected animal has died. On-farm biosecurity measures are crucial in controlling the introduction and spread of CWD.

Transmission to humans

There has been no known transmission of CWD to humans. Considerable surveillance of Creutzfeldt-Jakob disease in Canada and elsewhere has not provided any direct evidence to suggest that CWD may spread to humans.

But, scientific uncertainty remains for zoonotic (animal to human) and cross-species transmission.

Animal studies suggest that CWD prions could infect some types of non-human primates under experimental conditions. Experts continue to study whether this disease has the potential to infect other animals or humans and if so, under what circumstances. Infection would likely occur through:

  • food
  • other consumable products harvested from deer, moose, elk, caribou or reindeer (for example elk antler velvet)

As a precaution, the Government of Canada recommends that people not consume any part of an animal that has tested positive for CWD.


Although animals infected with CWD sometimes show signs, CWD can only be confirmed by testing specific tissues from an infected animal after it is dead.

The CFIA has officially approved certain CWD tests for surveillance and diagnostic purposes. The disease cannot reliably be detected in animals under 12 months of age, and there is no test available to certify that food or other consumable products (for example antler velvet) are completely free from CWD prions.

While a negative test result of an animal does not guarantee that it is not infected with CWD, it is considerably less likely to be. This reduces the potential risk of exposure to CWD.

There are certain live animal CWD tests that may be conducted on cervid herds for herd management purposes but are not approved to confirm a diagnosis.


No treatment or vaccine exists for CWD.

Researchers are working to find ways to better understand and detect CWD, develop a vaccine and identify methods that could help prevent the spread of prions in the environment.

Protecting farmed cervids from CWD

Measures taken to prevent the introduction and spread of CWD in Canada include the following:

  • mandatory reporting to the CFIA of all suspected cases of CWD under the Health of Animals Act
  • mandatory testing of all farmed cervids over the age of 12 months slaughtered in Yukon, Alberta, Saskatchewan, Manitoba, Ontario and Quebec
  • not allowing animals known to be positive for CWD to enter the commercial food chain
  • national chronic wasting disease herd certification programs for farmed cervids, with the focus on disease prevention and risk management

How cervid producers can help keep Canadians safe

Keeping food safe

Operators of abattoirs under federal inspection must, by law, evaluate each animal when it arrives at their facility in order to detect abnormal behaviour, physiology or appearance.

A CFIA inspector also inspects each animal to ensure that the ones showing potential signs of disease, including CWD, have been appropriately identified and segregated until a CFIA veterinarian can examine them.

If the animal is not slaughtered within 24 hours of this examination, a new examination and inspection must be performed. This is an important step, as one cannot detect any visible abnormalities that are characteristic of CWD in the carcass once the animal has been slaughtered.

What the operator is looking for: signs of the disease

If the CFIA veterinarian confirms that the animal has signs of the disease, it will be condemned and will not be permitted to proceed to the slaughter floor or to other areas of the establishment where edible products are being processed. The animal will be isolated, humanely euthanized and then sampled for CWD.

Other steps to control food safety risk from the disease

Slaughter of cervids under federal inspection is only conducted in Alberta and Quebec, which have mandatory testing of all slaughtered cervids over the age of 12 months.

Operators of abattoirs under federal inspection must retain all carcasses and edible parts of cervids until a negative test result for CWD is received.

It is recommended that operators clearly identify all parts of the animal and separate them to lower any possible risk to other products if the CWD result is positive. Once a negative test result is received, edible meat products may be released into the marketplace.

If a test result returns positive, all parts of the animal will be disposed of by federally approved prion destruction methods, such as burial, incineration or specified risk material (SRM) rendering.

Good manufacturing practices and hygienic measures are used to lower the risk of cross-contamination between products and from the environment.

Some measures in place include:

  • daily sanitation of the slaughter environment
  • ongoing sanitation and cleaning of tools and equipment
  • control of product flow
  • identification and segregation procedures

Consumers: How to protect yourself

To date, there has been no direct evidence to suggest that CWD may spread to humans. However, as a precaution, the Government of Canada recommends that people not consume any part of an animal that has tested positive for CWD.

There are many factors to consider when deciding to eat cervid meat harvested from areas with CWD, including the level of risk you are willing to accept.

How to reduce your potential risk

Do not consume meat from a known CWD-infected animal or from untested animals in areas where CWD has been found.

If you are buying meat through a retailer, make sure it comes from an establishment licensed by the federal or provincial government. Animals and consumable products harvested from animals known to be infected with CWD are not allowed to enter Canada's commercial food supply.

If you are given hunted cervid meat, ask if the animal was:

  • hunted in an area where CWD has been found
  • tested by provincial or territorial wildlife management authorities

Use all the available label information when selecting natural health products. Since the existence of a potential risk cannot be definitively excluded, you can avoid natural health products that contain materials from cervids by verifying the list of ingredients found on their labels.

Hunters: How to protect yourself

If you hunt, handle or eat deer, elk, caribou or moose, you should know about chronic wasting disease (CWD). There are many factors to consider including the level of risk you are willing to accept.

To be as safe as possible and decrease your potential risk of exposure to CWD, you should take the following steps when hunting in areas with CWD.

Before hunting

Check with your provincial or territorial wildlife authority to see if:

  • CWD has been found in the area
  • testing is available or required

Testing may not be available in every province or territory, and wildlife authorities may have specific recommendations.

While a negative test result of an animal does not guarantee that it is not infected with CWD, it is considerably less likely to be, which reduces the potential risk of exposure to CWD.

While hunting

Pay attention to the appearance and behavior of the animal and look for signs of CWD.

  • Report sick or dead animals to your provincial or territorial wildlife authority
  • Do not hunt, handle or eat an animal that appears to be sick, or that has died from an unknown cause

Field dressing

When field dressing, wear latex or rubber gloves and minimize the handling of parts that will be discarded.

The animal's brain, spinal cord, eyes, spleen, tonsils or lymph nodes may be higher risk. Normal field dressing of a carcass together with boning out will remove most, if not all, of these body parts. Cutting away all fatty tissue will remove remaining lymph nodes.

If you use parts of the carcass to tan the hide, minimize handling the head and the brain.


Wash hands thoroughly with soap and water after field dressing is completed.

Disinfect soiled tools with bleach as soon as possible, as this substance can decontaminate surfaces contaminated with prions.

Dilute the bleach to provide a final concentration of 2% (20,000 ppm) available chlorine. For example, most commercially available bleaches have 6% available chlorine listed on the label. In this case, mix 1 part bleach and 2 parts water (ratio 1:2) to attain the 2% concentration of available chlorine.


Appropriate disposal of unharvested parts of the carcass is important to reduce the risk of spread of CWD, including the brain and spinal column. Contact your provincial or territorial wildlife authority for more information.

After hunting

Have your animal tested for CWD before:

  • eating the meat and other edible products
  • preparing trophies
  • further handling

This is especially important in areas where CWD has been detected in the wild.

Do not eat an animal that has tested positive for CWD.

Commercial processing

If you have the animal commercially processed, ask that your animal be processed individually, without meat from other cervids being added.

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