Causes and Symptoms of Chronic Wasting Disease


Researchers are beginning to better understand Chronic Wasting Disease (CWD).

CWD appears to be caused by an abnormal protein called a prion.

Prions are concentrated in the animal’s brain, spinal cord, lymph glands, tonsils, eyes and spleen.



CWD can be spread by close contact between animals.

Animals exposed to a CWD-contaminated environment may also become infected. There is evidence the prions associated with the disease may remain infectious in the environment (e.g., soil) for years.



It can take months, and even years, from the time an animal is infected to when it shows signs of the disease.

Signs observed in deer or elk with CWD include:


  • emaciation (loss of body weight and body condition)
  • abnormal behaviour or indifference to human activity
  • increased salivation or drooling
  • tremors
  • stumbling, lack of coordination
  • difficulty or inefficiency in chewing or swallowing
  • increased drinking and urination
  • paralysis

If you see an animal displaying some or all of these signs, please report this information to the Ministry of Natural Resources.

Testing for CWD

There is no practical way to test a live animal for CWD. Testing can only be done by examining the lymph nodes or brain of a dead animal.

Related Links

For more information the following website is recommended. Note:  the website (listed below) is maintained by an organization outside of the Ontario government. This organization is solely responsible for the operation and information contained within its site.

Please participate in the 2014 CWD testing program if you harvest deer in these Southwestern Ontario WMUs: 82A, 82B, 82C, 83, 84, 85A, 85B, 85C