There are two kinds of “lump jaw.” Soft-tissue abscesses from wounds in the mouth and embedded grass seeds are easy to treat by lancing, draining and flushing; a bone infection is harder to eradicate. Geof Smith, professor of ruminant health and production medicine at North Carolina State University, says bony lumps are caused by Actinomyces bovis.

“These bacteria live in the soil, so there must be a penetrating wound in the mouth for it to enter the bone. It’s not transmitted from animal to animal,” explains Smith. A mouth wound could be caused by wire or foreign material in feed, chewing on sharp sticks or eating abrasive feed.

“Multiple cases on a farm may be due to stemmy hay or sticks in the feed, but it’s usually more sporadic; you only see a case every four or five years on a farm,” he says.

The bacteria may occasionally enter via the dental sockets when young animals are shedding baby teeth and permanent molars are starting to come in. This may be why the condition is often seen in 2- or 3-year-olds. A penetrating wound into the bone doesn’t have to come from inside the mouth. The animal may run into something sharp and develop infection. Bony lumps have been seen on the front of the face.

Clinical signs — painless enlargement on the side of the face, usually near the central molars — appear after infection gets in the bone. Some lumps enlarge very slowly over several months. A general thickening on the lower edge of the lower jawbone may not be noticed until it is quite large. More commonly, it’s a protrusion on the side of the bone, and more easily seen. The bony swelling is hard and immobile, compared with a soft tissue abscess that can be moved with your hand.

“For an accurate diagnosis we obtain pus or oozing fluid to culture. If it’s not open, we stick a needle into the bony lump for a small sample. If it’s a valuable animal, we may take a radiograph of the head to see how extensive the bone involvement is,” says Smith.

Unless treated, the infection continues; the lump keeps getting bigger. It may eventually break through the skin and discharge sticky fluid. In later stages the area may be painful and interfere with chewing.

“Damaged teeth may become loose. Generally it affects the cheek teeth, usually in the lower jaw,” explains Smith.

Sometimes infection spreads to soft tissues and involves muscles and lining of the throat. The animal may have trouble eating or breathing and humane euthanasia may be necessary. Since the condition progresses slowly, however, treatment can be started when the enlargement is first noticed.

It does no good to try to lance the lump; the bone can’t be drained. The usual treatment is sodium iodide into the jugular vein, repeated at least two or three times at seven- to 10-day intervals. Even this effort may not halt the infection; the lump may stop growing for a while and you can market the animal or get one or two more calves from her, before it starts growing again.

Some veterinarians use another antibiotic along with sodium iodide and feel this improves success rate.

“The most common antibiotics used for this purpose are penicillin and oxytetracycline (such as LA-200). Penicillin should be given once a day for at least seven days or until the next dose of sodium iodide. Some people prefer LA-200^® or Nuflor^® because those don’t have to be given so often,” says Smith. “All of these are extra-label treatments so you need approval from your veterinarian.”

Once the bone is enlarged, it won’t reduce in size.

“On a valuable animal, some of it can be removed surgically,” he says. “This reduces the size of the swelling and may also allow the IV sodium iodide to get into the bone a little better.”

Editor’s Note: Heather Smith Thomas is a freelancer and cattlewoman from Salmon, Idaho. 
​Angus Beef Bulletin EXTRA, Vol. 6, No. 9