Editors Blog

Lumpy Jaw is a Common Oddity Among Deer

A white-tailed doe with "lumpy jaw" infection. Photo by Dan Schmidt.

Each year, the Deer & Deer Hunting editorial offices receive hundreds of inquiries from hunters who have shot wild, weird and downright wacky-looking whitetails. And, in all of the years that I’ve helped answer your questions, I’ve seen dozens of photos of deer with a condition biologists call “lumpy jaw.” I had never seen this malady up close until I shot this doe with my muzzleloader in Missouri.

According to our state agency contacts in Maryland, this condition actually starts off as a viral infection. The MDNR reports, “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.”

Word of caution: Deer that have “lumpy jaw” emit an incredibly foul odor from their mouths. In other words, don’t spend too much time photographing at close range like I did. Gag reflex, big time.