Actinomycosis

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Actinomycosis

Also called bony lump jaw, or lumpy jaw

Description

There are two kinds of “lump jaw” in cattle.  Soft-tissue abscesses due to wounds in the mouth or embedded foreign bodies like sharp grass seeds are easy to treat by lancing, draining and flushing, but a bone infection takes diligent efforts to eradicate, and treatment may not be successful. The bony lump continues to grow.

Bone infections usually involve the lower jaw but occasionally occur on the upper jaw. A bacterium called Actinomyces bovis gets in alongside a tooth and settles in the bone at the bottom of the tooth. Bacteria may enter the bone through the dental sockets when young animals are shedding their baby teeth, when the permanent molars are starting to come in.

As these bacteria multiply, this sets up an inflammatory reaction in the bone. The affected bone is being resorbed internally, but because of the inflammation there is swelling.
    
Bone is a dynamic, living material and tries to repair itself. New layers of bone build up on the outside, even as the inside is being destroyed. The animal ends up with a hard bony swelling on the jawbone, in contrast to a soft tissue abscess that is just in the skin and mouth tissues,

A bone infection and inflammation results in a bony enlargement, usually in the area of the central molars. The lump may develop within a few weeks, or enlarge slowly over several months. Unless treated, the infection continues, and the lump keeps getting bigger. The bone infection may eventually break through the skin and discharge sticky fluid through one or more openings.  

The animal can get along with a bony lump for a while, but as the bone becomes more damaged the teeth may become loose in that area of the jaw and the animal has trouble chewing.

The affected bone is being absorbed and new bone is being laid down, but the new bone is not properly organized. It becomes weaker and as the bone changes, the teeth often become misaligned or loose, which makes it harder for the animal to chew, and she starts to lose weight. Once the cow starts losing weight she won’t milk very well, and can’t raise a good calf.  

The painless enlargement on the face is usually near the area of the central molars. If it’s on the lower jaw it may be just general thickening on the lower edge of the jawbone and might not be noticed until it is quite large. More commonly, a protrusion on the side of the bone occurs and is more easily seen. The bony swelling is very hard and immobile, compared with a soft tissue abscess that can be moved by pressure from your hand.  

For an accurate diagnosis, a veterinarian may collect some of the pus or oozing fluid to culture. If it’s not open and oozing, a needle can be inserted into the bony lump to get a small sample. If it’s a valuable animal, the vet might take a radiograph of the head to see how extensive the bone involvement is.

There is no effect on the animal’s general health at first, but in later stages the area may be painful and chewing feed is difficult. Generally it affects the cheek teeth, usually in the lower jaw, but occasionally the top teeth.

In long-standing cases the affected jawbone may become misaligned, and sometimes the infection spreads to soft tissues and involves the muscles and lining of the throat. The animal has trouble eating and becomes so thin that humane destruction is necessary.  Extensive swelling may also interfere with breathing or cause impaired digestion with periodic diarrhea or bloat. Since the condition progresses slowly, however, there is time to treat it before the animal’s health is compromised

Signs

    Painless enlargements on the face, thickening on lower jawbone, immobile lump that continues to enlarge, infection may eventually break through skin and discharge sticky fluid from multiple openings, difficulty eating, weight loss, difficulty swallowing in end stages.
Causes

Since these bacteria live in the soil and are present in the environment, there has to be some kind of penetrating wound in the mouth. This could be caused by anything sharp, such as wire or other foreign material in feed, chewing on sticks or eating abrasive feed.  

This infection is not transmitted from animal to animal. When there are multiple cases in the same time period on one farm, it’s usually due to coarse feed, stemmy hay or sharp material in the feed. Usually however, it’s sporadic, with maybe a case every 4 or 5 years on a farm.

The bone infection is usually due to a deeper or more penetrating wound than what typically causes a soft tissue abscess. Signs of bony lump jaw show up after the infection gets going in the bone. The infection usually gets started when a foreign body penetrates down to the bone alongside the teeth and takes bacteria with it. Once bacteria get down there they set up infection at the bottom of the tooth socket.

Young adults—especially 2 and 3 year olds—seem to have a higher incidence of bony lump jaw, perhaps because this is when they are shedding baby teeth and the permanent molars are coming in. This may make them more vulnerable, when teeth are loosening and coming through the gums. There might be an opening where a piece of feed or something else could get jammed into the tooth socket.

When baby teeth are being shed, the sockets may be exposed to injury from stickers or sharp material in the feed before the new teeth are fully erupted to fill those sockets.  

A penetrating wound into the bone doesn’t necessarily have to come from inside the mouth. The animal may run into something sharp and develop a bone infection and lump on the front of the face, for instance.


Prevention

There’s no way to completely prevent this disease or protect cattle because the bacteria are present in the environment—in soil and feed.


Treatment

Treatment is difficult. There haven’t been any improvements or new treatments for bony lump jaw. The traditional use of sodium iodide solution, given IV, is still considered one of the better treatments.

Success of treatment depends on how early the condition is detected. If you catch it early and treat it aggressively there is more chance for success. When there’s already a big bony lump it’s tough to halt the infection—in the more advanced cases.

The question is whether to treat the cow or just sell her. If she’s pregnant you might give her time to have that calf and raise it. If it’s a young cow and she’s in good shape when you noticing early signs, she’d be a good candidate to treat. If she’s older and has a large swelling and bony lump, you might not bother with treatment but just keep her long enough to raise her current calf if she hasn’t lost too much weight. If it’s a bull, sell him after the current breeding season.  

You might be able to halt the infection and inflammatory process with treatment, but the bone is weakened.  Depending on how far the disease has advanced, if the animal were to bang the jaw on something, it might fracture.
    
If the disease has been going on awhile and the mouth is compromised—the animal is not eating well and is losing weight—from a welfare standpoint that animal should be culled immediately, even if you have to just butcher her.
    
A bony lump must be treated from the inside out, with antibiotics via the bloodstream that serves the bone. It does no good to try to lance the lump; the infection in the bone can’t be drained. The usual treatment is sodium iodide into the jugular vein, repeated at least 2 or 3 times at 7 to 10 day intervals. Even this effort may not always halt the infection; the lump may stop growing awhile and you can market the animal or get one or two more calves from her, then it starts growing again.

Most veterinarians use sodium iodide (10 or 20% solution), giving a dose of about 70 milligrams per kilogram of body weight. A mature cow weighs about 500 kilograms.  

It’s important to avoid overdose, to prevent toxic reactions. Signs of iodine toxicity include flaky skin (large dandruff) and diarrhea. If you see those signs, reduce dosage for the next treatment. But if the animal seems normal after 7 to 10 days, give the full dose again.
    
Some veterinarians use another antibiotic along with sodium iodide and feel it improves success rate.  The most common antibiotics used for this purpose are penicillin and oxytetracycline (such as LA-200), though florfenicol (Nuflor) and penicillin G are also used. Penicillin should be given once a day for at least the first 7 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. Oxtetracycline is commonly use because it penetrates into bone (from the bloodstream) relatively well. The long-acting form gives adequate levels for 3 days, which reduces the number of treatments.

The animal should be monitored after treatment, to determine whether the treatment is helping or not. In three months, is the animal losing weight or holding its own? The swelling/lump in the jaw will never entirely disappear but if the animal is comfortable and maintaining weight, and not suffering, it can probably stay in the herd a while, especially if it’s a young cow. If the condition starts to worsen, it’s time to cull that animal. These infections often flare up again. Then the animal can’t eat properly, and there is also danger that the jaw could fracture.  

The goal in treatment is to kill the bacteria and stop the lesion from growing. If an owner doesn’t like the way it looks on a valuable animal, some of the bony lump can be removed surgically. This reduces the size of the swelling and may also allow the IV sodium iodide to get into the bone a little better. Some veterinarians feel that treatment success rates have been a little better when they’ve done surgery, but many animals respond just with sodium iodide.

About the Author

EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.

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