Chronic Wasting Disease (CWD) is a neurological illness affecting members of the deer family, including white-tailed deer, mule deer, elk, and moose. This disease is caused by misfolded proteins called prions, which accumulate in the brain and other tissues. When these prions cause normal proteins to misfold, they create sponge-like holes in the brain, leading to severe neurological damage. CWD is always fatal, and there is currently no cure or vaccine for affected animals. It progresses slowly, with symptoms often taking months or even years to appear after initial exposure.
Observable Physical Symptoms
One of the most noticeable physical signs of CWD is significant weight loss, often described as “wasting away,” despite the animal having access to food. This emaciation becomes progressively more severe, leading to a gaunt appearance where ribs may become visible. Another common symptom is excessive drooling or salivation, sometimes accompanied by teeth grinding, which can be due to difficulty swallowing. The deer’s coat may also appear rough, dull, or shaggy, lacking its usual healthy appearance.
Affected deer often exhibit a lowered head and ears, giving them a dejected appearance. Their eyes may develop a blank or vacant stare. These physical changes worsen over time, making the animal increasingly debilitated.
Changes in Deer Behavior
CWD also manifests through distinct behavioral abnormalities. Affected animals may become listless, showing decreased interaction with other deer and a lack of interest in their surroundings. Their coordination deteriorates, leading to an abnormal gait characterized by stumbling, poor balance, or a wide, exaggerated posture. They might also walk in repetitive patterns or circles.
A striking behavioral change is a loss of fear of humans or other natural predators, making them seem unusually tame or approachable. Additionally, deer with CWD often exhibit increased thirst and frequent urination, contributing to the spread of prions in the environment.
Differentiating CWD from Other Issues
Observing symptoms in a deer can suggest CWD, but visual cues alone are not definitive for diagnosis. Many conditions can cause a deer to appear sick, including starvation, injuries, or other diseases. For instance, Epizootic Hemorrhagic Disease (EHD) and Bluetongue (BT) viruses, spread by biting gnats, can cause fever, internal hemorrhaging, and lameness, sometimes leading to death near water sources. Unlike CWD, EHD outbreaks are often seasonal and can resolve with a hard frost.
Deer experiencing malnutrition or severe parasitic infections might also exhibit significant weight loss and a poor coat, similar to CWD. Unlike CWD, other conditions may be survivable or resolve on their own. A definitive diagnosis of CWD requires laboratory testing of tissue samples, typically from the brain and lymph nodes, which is performed post-mortem.
Reporting a Suspected Case
If you encounter a deer exhibiting signs consistent with CWD, report your observations to the appropriate wildlife authorities. Avoid approaching, touching, or disturbing the animal. Instead, contact your local state wildlife agency, Department of Natural Resources, or game warden.
When reporting, be prepared to provide specific details about the deer’s location, the symptoms observed, and the date and time of the sighting. Prompt reporting is crucial for disease surveillance, helping agencies track CWD and protect deer populations.