The following information is taken from the CWD Alliance website at cwd-info.org/faq:
"While yearlings and even fawns can contract CWD (often getting the disease in utero from their mother), late-stage CWD symptoms are usually only visible in adult animals because of CWD’s long incubation period (usually around 18 months but may be as long as two years). In most cases, animals with CWD show no visible, outward symptoms of the disease for all but the last few months of the disease’s cycle. Thus, the majority of infected animals are virtually impossible to distinguish from healthy, non-infected animals. Because CWD affects the neurological system of an infected animal first, other causes of mortality (predators, vehicle collisions, other diseases) usually remove the animals from the population far before outward signs of the disease become apparent.
However, if an infected animal survives to the final stage of this always-fatal disease, the most obvious and consistent clinical sign is emaciation. CWD affected animals continue to eat but amounts of feed consumed are reduced, leading to gradual loss of body condition. Excessive drinking and urination are also common in the terminal stages.
Behavioral changes also occur in the majority of cases of late-stage CWD, including decreased interactions with other animals, listlessness, lowering of the head, blank facial expression and repetitive walking in set patterns. In elk, behavioral changes may also include hyper-excitability and nervousness. Excessive salivation, drooling and grinding of the teeth also are observed.
It is important to note that the above-mentioned clinical signs alone are not sufficient to definitively diagnose CWD. There are other maladies that have symptoms that mimic those of CWD such as brain abscesses, trauma-related injuries, or other diseases such as epizootic hemorrhagic disease. Currently, the only conclusive diagnosis for CWD involves an examination of the brain, tonsils or lymph nodes performed after death to detect the presence of CWD prions."
Department of Natural Resources