Lumpy Jaw in White-tailed Deer

With the white-tailed deer hunting season now upon us, most hunters are already in the woods looking for that big, mature buck. However, as is often the case when in the field, hunters will see the strangest things — and sometimes those odd things include deer with different diseases and other issues. One fairly common problem in whitetail is lumpy jaw. The name “lumpy jaw” says it all because deer with this problem stick out; The animal looks like it has a lump between (or under) its jawbone and the hide.

The lumpy jaw many hunters witness is the result of adult arterial nematodes (Elaeophora schneideri). These worms live primarily in the whitetail’s carotid arteries. In fact, partial paralysis of the deer’s jaw muscles occurs when high arterial worm infestations reduce blood flow. As a result of jaw muscle paralysis, food becomes trapped inside the deer’s mouth and this food impaction leads to the lumpy jaw and/or swollen cheek appearance. The impaction often causes tooth loss, bone decay, and sometimes even death.

So now your thinking, how do white-tailed deer get lumpy jaw? Well, the common horsefly passes the nematode larvae from an infected deer to an uninfected one by feeding on deer blood. The horsefly carrying larvae-infected blood is ultimately what perpetuates this lumpy jaw condition in deer.

Luckily for property owners, hunters, and the deer, infection rates in are not high enough to impact white-tailed deer populations. Arterial worms, like most other deer issues, do not pose a risk to humans, but as a hunter I don’t like to think about the deer I harvest as having arterial worms, nasal bots, or any other of the many diseases, viruses, or things deer can possibly tote around.

And on that note, arterial worms are not the only creatures that can give white-tailed deer that lumpy jaw appearance. A bacterium called Actinomyces bovis can also cause an infection of the jawbone. This bacterium is actually a common inhabitant of the mouths of healthy whitetail. It is when a sharp object such as a thorn punctures the inner lining of the mouth that A. bovis bacteria are allowed to invade the tissues.

Additionally, healthy deer — like all animals — can simply get large or odd-shaped food items caught in their mouth. However, food impaction in white-tailed deer is often the result of arterial worms that cause muscle issues that lead to food impaction and lumpy jaw syndrome. As mentioned previously, deer with lumpy jaw do not pose a health problem for hunters and the meat can be safely consumed.