Deer Diseases in Tennessee

Arterial worm is a parasitic roundworm that lives in the carotid arteries and other major blood vessels of deer. The worm is transmitted by horse flies and deer flies. In white-tailed deer, arterial worm infections are usually tolerated without severe disease. In elk and moose, the same parasite causes a condition called elaeophorosis — blindness, neurological damage, and death. In Tennessee white-tails, arterial worm is common but rarely the primary cause of death. A deer found dead with no other obvious cause may have had a heavy arterial worm burden contributing to poor body condition.

Brain abscesses in deer are bacterial infections of the skull and brain, most commonly caused by Trueperella pyogenes. They typically develop from antler injuries — bacteria enter through damaged velvet or antler breakage and migrate to the skull. Affected bucks are usually mature males. The abscess causes neurological symptoms including circling, head tilt, loss of coordination, and loss of fear of humans. Brain abscess deer are sometimes mistaken for CWD or rabies. The condition is not contagious to other deer, humans, or pets under normal circumstances.

Brainworm is a parasitic roundworm that completes part of its life cycle in white-tailed deer and part in terrestrial snails and slugs. White-tailed deer are the natural host — they carry the parasite with minimal symptoms. The worm becomes dangerous when it infects aberrant hosts: moose, elk, caribou, reindeer, and llamas. In these animals, brainworm migrates through the spinal cord and brain, causing fatal neurological disease. In Tennessee, brainworm is common in the white-tail population. Deer found with neurological symptoms — stumbling, circling, loss of fear — may have brainworm, though CWD should also be considered and reported to TWRA.

Bovine tuberculosis (bTB) is a bacterial disease caused by Mycobacterium bovis that affects deer, cattle, bison, elk, and humans. It is a zoonotic disease — it can spread from animals to people. In Tennessee, bTB is rare in deer but is a serious concern because of its potential to spread to cattle herds and cause significant agricultural and economic damage. A confirmed bTB case in a deer herd can trigger mandatory cattle testing and movement restrictions across a county. Deer with bTB typically show progressive weight loss, respiratory distress, and enlarged lymph nodes. The disease is spread through respiratory secretions and direct contact.

Chronic Wasting Disease is a fatal prion disease of deer, elk, and moose. It is caused by misfolded proteins called prions that accumulate in the brain and nervous system, causing progressive neurological deterioration. CWD is always fatal. There is no treatment and no vaccine. Prions persist in soil for years to decades and are not destroyed by standard disinfection. CWD was first confirmed in Tennessee in 2018. TWRA maintains Surveillance and Containment Zones with carcass transport restrictions. Any deer showing CWD signs must be reported to TWRA before the carcass is moved.

Dermatophilosis is a bacterial skin disease caused by Dermatophilus congolensis that affects deer, cattle, horses, sheep, and occasionally humans. In deer, it causes crusty, scab-like lesions on the skin — most commonly on the face, neck, and legs. The disease is associated with wet conditions and skin injuries. It is rarely fatal on its own but can weaken deer and make them susceptible to secondary infections and predation. Dermatophilosis is more common in deer that are already stressed by poor nutrition or other disease. It is occasionally seen in Middle Tennessee deer after prolonged wet seasons.

Giant liver flukes are large parasitic flatworms that infect the livers of deer, elk, and moose. White-tailed deer are a natural host — they typically survive infection, though heavy burdens cause liver damage and reduced body condition. The flukes complete part of their life cycle in aquatic snails and are acquired when deer graze on wet vegetation near ponds, streams, and wetlands. In sheep and goats, giant liver flukes are fatal — the parasite migrates through the liver causing massive hemorrhage. Property owners with sheep or goats near deer habitat should be aware of this risk. In Tennessee, giant liver flukes are most common in deer that use wetland and bottomland habitats.

Hemorrhagic disease is the leading infectious cause of deer death in the eastern United States. It encompasses two related diseases — Epizootic Hemorrhagic Disease (EHD) and Bluetongue — both caused by orbiviruses transmitted by biting midges (Culicoides). The diseases cause internal hemorrhaging, high fever, and rapid death. Deer are found dead near water sources in late summer and fall — typically August through October — because fever drives them to seek water. Multiple deer found dead at the same pond or creek during this period is a classic EHD outbreak pattern. The disease does not persist in soil and poses no risk to humans or dogs.

Deer papillomavirus causes two distinct conditions in white-tailed deer: cutaneous fibromas (warts) and oral papillomas. Cutaneous fibromas are firm, gray-black, cauliflower-like growths on the skin — most commonly on the neck, shoulders, and face. They can grow very large and are alarming in appearance, but they are benign tumors that rarely affect the deer's health unless they obstruct vision or movement. Oral papillomas are wart-like growths inside the mouth. A separate but related condition — head abscesses — can develop when fibromas become infected. Deer with large facial fibromas or head abscesses are frequently reported by property owners who mistake them for serious disease. The virus is species-specific and does not infect humans, dogs, or other animals.