Keeping Wisconsin Deer Healthy

Information on Deer Diseases

Wisconsin is home to over 1.5 million white-tailed deer. A source of pride for Wisconsin's citizens and the state's official wild mammal, whitetails provide many forms of enjoyment to Wisconsin citizens from wildlife watchers to hunters.

How Do We Keep Wisconsin's Deer Herd Healthy?

Monitoring the health of the deer herd is the job of the DNR's Bureau of Wildlife Management, Wildlife Health Program. In cooperation with hunters, annual health testing is done on deer harvested in the Fall hunt. Sick and dead deer reported to DNR wildlife managers are also examined for disease throughout the year.

This document describes three infectious diseases with the potential to cause great damage to Wisconsin's deer. Bovine Tuberculosis, Chronic Wasting Disease, and Cranial Abscessation Syndrome are a health risk to Wisconsin's whitetails.

You can help keep the deer herd healthy. Early detection is the best defense we have in controlling these infectious diseases. If you see a deer with any of the disease signs described in this brochure, contact your local DNR office.

Bovine Tuberculosis

Bovine Tuberculosis (TB) is a contagious respiratory disease caused by the bacterium Mycobacterium bovis. Bovine TB can infect most warm blooded animals, including humans. The federal government has done nationwide testing of cattle herds to control bovine TB, but it still occurs in cattle, penned exotic livestock such as elk, and wild deer. TB has been diagnosed in captive elk herds in several states including Wisconsin. Michigan has found TB in their free-ranging white-tailed deer since 1994.

Are Wisconsin wild deer infected with TB?

We do not believe our wild deer are TB infected. Surveillance of Wisconsin deer for TB has been done since 1996, with more than 1500 deer tested and no positive animals found. WDNR will continue annual testing to monitor for TB. As a hunter, you may be asked by DNR personnel to provide a small tissue sample from the head of your deer. This is voluntary, but your cooperation is important in detecting this disease.

Is deer TB a human health hazard?

Transmission of bovine TB to people can occur, but it is rare. TB is generally transmitted through the air by coughing and sneezing, and it is highly unlikely a person would contract the disease from field dressing or eating the meat of an infected deer. However, it is always a good idea to wear gloves when field dressing any animal. There is no specific test that can be easily done to check for TB in deer meat. Michigan recommends any deer meat collected from their TB infected area should not be smoked or made into sausage or jerky, but be thoroughly cooked until it is no longer pink, and juice from the meat runs clear.

For the most up-to-date information on Chronic Wasting Disease (CWD), please visit our CWD home page.

CWD is a brain disease related to Bovine Spongiform Encephalopathy, also known as "Mad Cow Disease." CWD affects elk, mule deer and white-tailed deer. Researchers are just beginning to understand CWD. CWD appears to be caused by an abnormal protein called a prion. CWD can be spread by close contact between animals, and animals exposed to a CWD-contaminated environment may also become infected. Usually, months to years pass from when the animal is infected to when it shows signs of disease. Classic CWD signs in deer/elk 18 months or older include poor body condition, tremors, stumbling, increased salivation, difficulty swallowing, and excessive thirst or urination.

Are Wisconsin wild deer infected with CWD?

Please visit our CWD home page for up-to-date information.

Is CWD a human health hazard?

Please visit our CWD home page for up-to-date information.

Brain Abscesses or Cranial Abscessation Syndrome

Brain abscesses are usually caused when Actinomyces pyogenes bacteria enter a wound in the velvet of a buck's antlers, through a broken antler, or through the pedicle (antler base) after antlers shed. After entering through a wound, the bacteria can actually eat through the skull causing an abscess in the brain.

Have brain abscesses been found in Wisconsin wild deer?

Adult antlered deer from all over Wisconsin have been diagnosed with Cranial Abscessation Syndrome (CAS). Bucks appear blind, are uncoordinated, and may show abnormal behavior such as aggression toward people and stationary objects, or not moving when approached by people or dogs. Signs of CAS include swollen eyes, broken antlers weeping fluid, swollen ankles, foot sores, and lameness. Pus may be observed at the pedicle or in eye sockets.

As wounds the bacteria enter are often the result of battles between older dominant bucks, CAS may account for up to six percent of natural mortality in bucks. This is a concern for quality deer management practices intended to increase the number of trophy class bucks available to hunters.

Is CAS a human health hazard?

If you harvest an adult buck with pus weeping from antler pedicles or eye sockets, the deer may have this bacterial infection. Though the meat may be contaminated with the Actinomyces pyogenes bacteria, the infection is usually limited to the head. No part of the head should be eaten. The meat is safe to eat as normal cooking temperatures will destroy the bacteria.

What Can I Do to Help Keep Wisconsin's Deer Healthy?

Transmission of Bovine Tuberculosis, Chronic Wasting Disease, and Cranial Abscessation Syndrome is enhanced when high deer numbers and excessive feeding cause congregation and prolonged contact of deer, so we must all prevent these situations. If you see any signs suggestive of these three deer diseases, save the affected tissues and contact your nearest DNR office. If you have questions about deer health, contact Wildlife Health.

Information on proper handling of venison. (PDF, 234KB)(Exit DNR)

Questions for Wildlife Health.

Questions for Wildlife Management