As the name implies, cattle infected with the condition known as lumpy jaw develop hard lumps along the jaw, or rarely, other facial bones.
The disease is a severe, deep bone infection that typically starts when there is damage to the gums. Infection establishes in the tooth socket and spreads from there to invade deep into the soft tissues below the gums and eventually into the jaw bone. Inflammation, pus and dead tissues fill pockets within the bone and if left untreated, the infection eventually destroys the jaw bone.
There is also reaction to the infection from the bone itself. In response to the injury, the bone proliferates, creating the characteristic hard lumps. But the new bone is also weak, disorganized and fragile. So while there is bone destruction, there is also proliferation.
The affected area takes on a honey-comb appearance and this weakened jaw bone is prone to fracturing.
At the same time, the body puts down lots of scar tissue in an attempt to wall off the infection. This fibrous scar tissue is much weaker than healthy bone and also makes it challenging for antibiotics and cells of the immune system to penetrate the infected area.
Animals develop lumpy jaw after a break in the inner surface of the mouth. This allows the causative bacteria, Actinomyces bovis, to enter and begin the infection. These bacteria are particularly aggressive and invasive. In some ways, they behave more like a fungal infection than a bacterium.
Other species besides cattle can develop lumpy jaw or infections with the bacteria in other areas of the body. These include sheep, goats, horses and even dogs. Among wild animals, bighorn sheep in North America also develop this disease. While the bones of the jaw are most often affected, this infection can also occur less frequently in the bones of the upper jaw and skull.
Signs of the disease include an obvious but slow-growing swelling of the jaw, typically restricted to one side. The swelling is hard and immovable due to the new bone formation.
The infection can also loosen teeth in their sockets and some teeth may become misaligned or even fall out. If this occurs, the animal may have difficulty eating.
There are often sores or ulcers that drain pus from the infected area. These sores can be on the inside of the cheeks or drain outside through the skin. Cattle with this disease lose condition, both from the difficulty eating and the body’s response to infection. The disease is painful.
Although lumpy jaw has obvious signs, additional testing such as bacterial culture, X-rays and biopsy of the affected area for pathology assessment can aid diagnosis.
Treatment options are limited and usually attempted so that a valuable animal can live long enough to calve, or breed in the case of bulls. There is no curative treatment. Multiple intravenous injections of sodium iodine, sometimes in combination with antibiotics, are used to stop the progression of the infection. The boney mass will remain but may spread slower. In animals with advanced disease, humane culling is the best option.
Prevention is a challenge since the bacteria are normally present in the mouth of cattle without causing disease. There is no protective vaccine available.
Coarse feed, sticks, wire and other sharp objects are thought to be a leading case of the mouth damage that leads to infection so eliminating foreign material from feed bunks is important. Feed that is particularly coarse, or that contains sticks or plant awns, should be avoided to reduce the likelihood of cattle developing lumpy jaw.
Dr. Jamie Rothenburger is a veterinarian who practices pathology and is an assistant professor at the University of Calgary’s Faculty of Veterinary Medicine. Twitter: @JRothenburger