Lumps and abscesses on deer

Deer and other wildlife occasionally have lumps or abscesses for a variety of reasons and most are usually insignificant to the health of the animal and to humans.

A condition known as caseous lymphadenitis (CL) -- which can produce lumpy swellings and abscesses in the lymph node area of the head, neck, and groin -- has occasionally been detected in white-tailed and mule deer in Washington and many other parts of western North America for many decades.

The CL condition, which develops with infections from the bacterium Corynebacterium pseudotuberculosis, is also found in domestic cattle, horses, goats and sheep. It can spread from animal to animal through contact with ruptured lesions, contaminated soil or feed, and flies.

Potential transmission to humans

Although rare, CL can potentially be transmitted from animals to humans. Most such cases have occurred in sheep shearers with broken skin or abrasions after handling infected animals. Those cases have been successfully treated with antibiotics.

There are no reports of transmission from harvested deer to hunters, and properly handled and thoroughly cooked game meat is safe to eat.

CL in wildlife and livestock

The U.S. Department of Agriculture does not mandate reports of CL in domestic livestock, but a 2009 National Animal Health Monitoring Study found about one-third of goat producers with herds larger than 100 animals reported CL symptoms.

Incident reports indicate CL is uncommon in wildlife, but it is likely under-reported.

Cases in Washington

Although individual CL cases in deer have occasionally been found throughout Washington, Idaho, Montana, and British Columbia, a few cases have recently occurred in southeast Washington.

In 2008, a hunter-harvested white-tailed buck deer in the Mill Creek drainage east of Walla Walla was reported with CL symptoms and testing of tissue samples revealed C. pseudotuberculosis. In 2016, a hunter-harvested white-tailed buck deer from the Jasper Mountain area, northeast of Walla Walla, was reported with swollen lymph nodes. Local wildlife biologists collected tissue samples that tested positive for C. pseudotuberculosis.

Another hunter-harvested white-tailed buck deer from the Mud Creek area northeast of Dixie was photographed with lumpy swellings characteristic of CL, but no samples were collected for diagnosis. There were also reported sightings in 2016 of deer with lumps from the Jasper Mountain area south to the Mill Creek area.

The CL condition appears to have been present among southeast Washington deer for at least a decade and likely poses little risk to the overall population.

Monitoring and prevention

The Washington Department of Fish and Wildlife will continue routine wildlife disease monitoring, including sample testing from potential cases reported by hunters.

As with all potential wildlife diseases, hunters should use standard game meat handling hygiene. Use protective gloves, avoid cutting into lumps and abscesses but cut away and discard them, clean equipment, and thoroughly cook meat. See more information at our Wild Game Meat Food Safety webpage.