How to Recognize 5 Common, Lethal Deer Diseases
Daniel Xu 11.04.14
Like any other animal, deer are susceptible to a host of contagious diseases, illnesses, and nasty parasites. While only a small percentage of deer actually fall prey to these ailments, some of these diseases are very dangerous. It is not unheard of for entire herds of captive deer to be destroyed to keep some diseases, such as chronic wasting disease, from spreading to wild populations. Even though most deer illnesses are harmless to humans, it is still important to be educated about them. Hunters discover all the time that the animals they harvest are less than healthy, and this quick guide will help you recognize signs of five of the most common deer diseases. Parasites are not included in this list.
As always, using rubber gloves when field-dressing a deer and cooking the meat thoroughly will help lower the risk of any contamination.
Epizootic hemorrhagic disease (EHD)
EHD is a disease that can kill large numbers of animals, usually deer species, in a very short period of time. It is arguably one of the largest threats to deer in North America, and tends to occur in the summer. Deer infected with the illness can show symptoms as early as seven days after transmission, including loss of appetite, weakness, fever, becoming oblivious to predators, and eventually fatal hemorrhages. Other animals such as sheep and cattle can also contract the disease, although it is rarely fatal for domesticated animals. EHD is transmitted by the biting midge. So far over 30 states have reported cases of EHD. EHD (along with chronic wasting disease) is considered one of the major threats to wild deer nationwide. EHD does not affect humans and experts say that meat from an affected animal can be consumed.
How to recognize EHD:
According to the Michigan Department of Natural Resources, common signs of EHD are lesions. As you begin to skin the deer, you will discover hemorrhagic material just under the skull, sometimes around the muscle bundles. The organs might also be congested with blood and will slowly ooze out during the skinning process. There may be external signs as well, including swelling and blood “leaking” out of the nose or mouth. Watch the video below to learn more.
Bluetongue virus
Experts often compare bluetongue disease to EHD, as both share the same symptoms, affect the same species, and are not considered contagious. Bluetongue, however, has a reputation for causing affected animals to develop foot lesions. In animals like deer, elk, pronghorn, and cattle, it can be extremely painful and eventually causes death. The erratic movements caused by the foot lesions have led bluetongue to be known as the “dancing disease.”
“Both diseases are spread to animals by the bite of a certain type of midge,” said New Jersey Division of Fish and Wildlife Director Dave Chanda. “Neither disease can be transmitted to people. While EHD is only found in deer populations, the bites of the midge can transmit bluetongue to certain types of livestock.”
How to recognize bluetongue disease:
Bluetongue has the same symptoms as EHD, save for a high chance for animals to develop foot deformities. The lack of oxygen in the animal’s blood will also drain the color from certain parts of their body, especially the oral mucosa. This is what gives this disease its name, by turning the deer’s tongue blue. You can learn more about the disease in the video below.
Chronic wasting disease (CWD)
CWD is a neurological disease that affects deer, elk, and related species. Common symptoms include weight loss, excessive salivation, appetite loss, and other abnormal behavior. It is contagious, always fatal, and considered to pose a major threat to wildlife populations. It is not believed to affect humans.
The first case of CWD in North America was discovered in Colorado in 1967. Since then the disease has spread to wild deer populations in Illinois, Kansas, Maryland, Minnesota, Missouri, Nebraska, New Mexico, New York, North Dakota, South Dakota, Texas, Utah, Virginia, West Virginia, Wisconsin, Wyoming, and certain locations in Canada. As of yet, there is no known cure or method to test live animals.
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How big of a problem does CWD pose to deer herds? The Iowa Department of Agriculture and Land Stewardship quarantined an entire captive deer herd last month due to the presence of CWD within the group. The herd—356 animals—was destroyed to stop CWD from being spread to wild deer, which are extremely vulnerable to the disease. Even the chance of a single animal being infected with the disease could lead to a quarantine of captive deer herds across the state, as seen in Ohio’s first case of CWD discovered last month.
Many officials advise against eating meat from deer that tests positive for CWD.
How to recognize CWD:
CWD is very hard to recognize on dead deer, although live deer with CWD may stagger, drool excessively, and have rough coats. Animals afflicted with CWD will likely be skinny and have developed lesions as well. Researchers studying the disease will often harvest lymph nodes for testing, which is one of the only ways to be sure. Watch the video below to find out more.
Mange and hair loss
Mange is a contagious skin disease caused by mites that often results in hair loss and thickening of the skin. Although mange is not as common as the other diseases on this list, it can be fatal to deer, especially fawns. Other conditions that cause deer to shed their coats, such as lice or “Hair Loss Syndrome,” also can have drastic impacts on deer herds. In these cases, the animals develop a hypersensitivity to the pests and will engage in excessive grooming. That leads to the loss of guard hairs, which leave patchy yellow or white spots on their sides.
How to recognize mange or hair loss:
This one is relatively easy. If you see hair loss or the presence of mites or lice, it is likely that the deer is suffering from mange or some other type of hair loss illness. Thick, wrinkled skin is also a sign of mange. You can learn more in this video.
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“Deer warts” or cutaneous fibromas
Perhaps the strangest-looking entry on this list is the condition commonly known as “deer warts.”
No, it’s not a severe case of deer acne, but the grotesque and wartlike growths called cutaneous fibromas may leave some outdoorsmen confused. Common questions are often: is the meat safe to eat? Is it a symptom of chronic wasting disease? Is it contagious?
The answers would be yes, no, and no, respectively. Cutaneous fibromas are caused by a virus that affects the skin. Bucks are more likely to contract the virus through wounds, often after a fight with another male or by rubbing antlers on a tree. Other modes of infection involve biting insects, which seem to be a never-ending hazard for deer. The virus that causes cutaneous fibromas is found throughout the entirety of the whitetail deer’s range.
This bizarre disease is also perhaps the least dangerous one on the list. Although cutaneous fibromas can cause death by either blinding the deer, rendering it immobile, or growing in such a way that it finds it difficult to eat, the disease is usually not fatal.
The meat from a deer with this condition is good to eat, granted that there has been no bacterial infection.
How to recognize cutaneous fibromas:
Big, scary-looking “deer acne.” You can see an example of a deer with an extreme case of cutaneous fibromas below:
Are there any other deer ailments hunters should be aware of? Let us know in the comments.
