Diseases and Parasites of Maryland Deer

Arterial Worm (Lumpy Jaw)

The adult arterial nematode worm lives primarily in the deer’s carotid arteries. High worm infestations reduce blood flow, which causes partial paralysis of the deer’s jaw muscles. Food becomes impacted inside the deer’s mouth due to the jaw muscle paralysis. The food impaction causes the “lumpy jaw” appearance. The common horsefly passes the nematode larvae from an infected deer to an uninfected one by feeding on deer blood. Infection rates are not high enough to impact deer populations and no human health implication has been reported.

Close-up photo of deer showing lump on jaw


Photographs are used with the permission of the Southeastern Cooperative Wildlife Disease Study located at the University of Georgia, College of Veterinary Medicine.

For more information about white-tailed deer parasites and diseases, visit the Southeastern Cooperative Wildlife Disease Study Web site. The publication “Field Manual of Wildlife Diseases in the Southeastern United States” (third edition) by William R. Davidson and Victor F. Nettles explains and describes in detail parasites and diseases of southeastern birds and mammals. It is available for purchase through the website listed above.

Maryland Department of Natural Resources
Wildlife and Heritage Service
Tawes State Office Building, E-1
Annapolis MD 21401
Toll-free in Maryland: 1-877-620-8DNR, Ext. 8540

E-Mail: customerservice.dnr@maryland.gov

Diseases and Parasites of Maryland Deer