Common Whitetail Diseases
Every hunting season we get questions like…We’ve seen a deer that looks like he’s covered with warts. What’s wrong with him?” “Is something wrong with our deer?” This instance refers to diseases common to white-tailed deer. Hopefully this article will address questions and shed some light on the more common deer diseases, causes, and their management implications. The information for this article was derived from the Field Manual of Wildlife Diseases in the Southeastern United States by Davidson and Nettles 1997, Southeastern Cooperative Wildlife Disease Study.
A common deer “disease” is cutaneous fibroma. Many hunters refer to these as “deer warts”. Basically fibromas are hairless tumors caused by a virus and found on the skin of deer. Experimental infections show that fibromas are usually temporary and do not cause any major issues. However, occasionally deer can develop massive tumors interfering with sight, respiration, walking, or feeding. Fibromas can be found on any part of the skin and can range in size from ¼ – 8 or more inches in diameter. Typically fibromas are smooth and black to gray in color and can sometimes have a “warty” appearance.
The virus is thought to be transmitted from deer to deer via biting insects and through direct contact with contaminated materials that may scrape or scratch the skin. Cattle, sheep, horses, and rabbits are not susceptible to this particular virus. There have been no reports of human infection; however large tumors with secondary bacterial infection would cause the meat to be unsuitable for consumption.
The arterial worm is a naturally-occurring nematode (round worm) in mule deer, elk, white-tailed deer, and domestic sheep in areas where this parasite is common. The most common sign of an arterial worm infection is facial swelling due to food impactions, tooth loss, and occasionally fracture or deterioration of the jawbone. In some instances blood flow to the head may be obstructed due to blockages of the carotid arteries. Arterial worm infection should be suspected in any white-tailed deer with a food impaction. Removal of worms from deer with food impactions serves as clinical confirmation of infection. The life cycle of this worm can be a little complicated so bear with me. Adult worms live primarily in the carotid arteries. Females produce larvae that become lodged in the capillaries of the skin (especially the head region). These larvae are ingested by horseflies and reach the infective stage in roughly 14 days. At this point, the larvae begin to migrate to the mouthparts of the fly and are transmitted to other deer when the horsefly feeds. Once inside the deer, the larvae move to the arteries of the brain where more development occurs. After three to four weeks, the worms then return to the carotid arteries. Arterial worm infection can occasionally cause mortality in whitetails, and food impaction is seen more so in older deer. There have been no reported human health implications associated with arterial worm infection in deer.
Hunters and taxidermists that prepare a lot of European mounts are probably well familiar with nasal bots. Nasal bots are larvae of a specific genus of fly. The bots do not really cause any lesions in deer. Many of North America’s cervids are hosts for nasal bots. Clinical diagnosis of nasal bots is the recovery of the larvae. The life cycle for nasal bots begins with adult female flies laying eggs on the skin around the nose or mouth of deer. The larvae are released when the eggs are licked by deer. The larvae then migrate to the nasal passages and molt. The fully developed larvae exit the deer through snorting/sneezing. Even in high numbers, nasal bots are not thought to be harmful to deer. However, hunters tend to be concerned when they discover them.
Rest assured there are no risks to human health from deer with nasal bots.
These are just a few of the more common deer diseases managers and hunters should be familiar with. Again, the information derived for this article were taken from the Field Manual of Wildlife Diseases in the Southeastern United States produced by the Southeastern Cooperative Wildlife Disease Study (SCWDS) in Athens, GA. SCWDS is a valuable resource to state wildlife agencies and landowners as a source for information and assistance with disease-related issues pertaining to the lands they manage. I would highly recommend purchasing the field manual (www.scwds.org) to help you identify diseases, ensure that proper samples are collected for diagnostic testing, and if nothing else to impress your hunting buddies when you know what a cutaneous fibroma is.
Click here for more information on wildlife disease http://vet.uga.edu/scwds