Deer Diseases

It’s almost deer hunting season. Hunters and landowners head out to the ranch or hunting lease to begin the fall ritual of filling feeders and putting out game cameras. When landowners and hunters take to the field, they occasionally find whitetail with various deer diseases that afflict the species we so love to manage and hunt. Questions will often start with “can you tell me what is wrong with the deer in this picture.” Many times these observations occur from trail cameras photos or after a deer was harvested.

Deer disease and parasite issues are not uncommon and hunters run across this sort of thing from time to time. Most of us may not know what disease may be affecting a deer, but we definitely know something is wrong. Just like us, whitetail deer are prone to one sort of illness or another. This is how nature makes the deer population stronger (survival of the fittest). Below are a few of the common whitetail deer disease and health concerns that are often encountered this time of year.

Cutaneous Fribroma – Virus that Effects Skin

Cutaneous fibromas, or deer warts, are hairless tumors caused by a virus and are found on the surface of the skin of infected deer. They can appear anywhere on the body and are usually temporary. Their size varies and can become quite large causing them to crack and bleed. When they do, secondary bacterial infections can occur. No reports of cutaneous fibroma in humans are known. The meat is safe to eat provided no secondary infection is occurring.

Cutaneous Fibroma ("Warts") in Deer

Most deer with fibromas or warts will not be as severe as the deer in the photo above. Most deer that hunters see with fibromas will have one up to a few. However, there are extreme cases and deer can have 50 percent or more of their body covered in fibromas! These deer will potentially suffer from secondary infections.

Epizootic Hemorrhagic Disease and Blue Tongue in Deer

Hemorrhagic disease in deer can be caused by one of two viruses, epizootic hemorrhagic disease (EHD) virus or bluetongue (BT) virus. The virus is spread by a small, biting midge fly (Culicoides). Signs of active disease in deer are variable, but can include depression, fever, irregular breathing, and swelling in the head, neck, and/or tongue. On occasion, animals can become disabled for weeks by lameness or poor body condition. Deer that die from EHD/BT will often die in or around water, trying to cool the fever the disease brings on.

Long Hooves Indicate Deer Survived BT/EH Disease

EHD and BT are usually summertime deer diseases but can be observed in late fall, if it is warm. Cooler weather, such as that during the general deer hunting season, typically causes the flies to die back and become less active. Animals that do not succumb to the disease can exhibit hooves that have been sloughed or become elongated due to growth interruptions at the point of the foot where the hoof is devel-oping. Neither of these viruses is infectious to humans. As with other diseases dis-cussed here, the deer is safe to consume barring any additional infections.

Ticks and Keds – Deer Parasites

Most hunters have harvested a deer at one time or another and noticed ticks on the carcass. Ticks do not generally cause health issues for deer unless a heavy infestation is occurring. During these infestation events, fawns can have an increased mortality due to anemia, and secondary infections can occur in adults at the bite site. In cases of secondary bacterial infections the meat should not be consumed. Precaution should be taken when handling carcasses when ticks are present since some species of ticks can carry diseases, such as lyme disease, known to infect people.

Deer Ticks - Not a Deer Disease, But Commonly Found on Whitetail

Keds are an insect found on deer. They are mentioned here because they are often misidentified as ticks. They are distinguished from ticks by the number of legs (keds have 6 legs, ticks have 8). Keds have no health implications for deer or people.

Food Impactions – Not Exactly a Deer Disease

Food impaction (lumpy jaw) is a condition illustrated by a large lump of vegetative material found under the skin in the jaw area of a deer. The cause of food impaction is not clearly understood, but is believed to be associated with the presence of an arterial worm (Elaeophora schneideri). Arterial worms live mainly in the carotid artery, but will occasionally be found in smaller arteries in the limbs. When they make their way to arteries in the jaw, food impactions are believed to occur.

Food Impaction or Lumpy Jaw Caused by Arterial Worms

No known human health risks are associated with arterial worms. Deer can recover from these impactions and the meat is safe to eat provided there are no additional infections occurring in the body.

Nasal Bots – Also Not a Disease

This is one that is commonly seen. Nasal bots are the larval form of a fly found in the Genus Cephenemyia. The fly will lay a cluster of eggs around the nose and mouth of a deer. The eggs hatch and the larvae migrate into the nose to grow. They eventually make their way into skin folds in the back of the deer’s mouth called the retropharyngeal pouches.

Nasal Bots in Whitetail Deer Esophagus

When the larvae are fully grown (approximately 3/4 to 1 inch), they migrate back out of the deer’s nose into the ground to finish developing into an adult fly. These fly larvae pose no threat to the deer and are only a minor nuisance to the host animal. They pose no risk to humans and the meat is not affected, so it is safe to consume. Most deer will have nasal bots in Texas. Commonly seen exiting a deer’s nose after the animal is dead. Can also be encountered in the back of the esophagus when cutting off the head (photo).

Chronic Wasting Disease in Deer

Chronic Wasting Disease (CWD) is a neurological disease in whitetail deer, mule deer, elk, moose and other members of the deer family, known as cervids. The disease was first recognized mule deer in 1967 in Colorado. This disease is not yet widespread in Texas, but it does present numerous challenges for state wildlife agencies across North America. Of concern is the potential for significant declines within deer, elk, or other susceptible cervid populations.

Chronic Wasting Disease in Whitetail Buck

Because eradication is nearly impossible once CWD becomes established in a population, it is imperative that a sound CWD management program is established to reduce the severity of implications resulting from the disease. CWD in Texas is a new one. Itwas found in far west Texas in 2012, near the Texas-New Mexico border.

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