BONE DAMAGE

Broken and healed deer jaw and rib bones.

Wild animals are often exposed to dangerous situations that can result in injury and/ or death. Collisions with motor vehicles are a very common example of this, but there are others too. Fights with another individual, whether of the same species or not, is another. Running through areas of downed trees or in rocky areas can result in a leg getting stuck and then broken. I have known of injuries to deer and moose from slipping on slick surfaces and falling off ledges.

Sometimes the injuries are fatal (either immediately or hours to days later); sometimes the animal is shot because the injuries are too serious for it to recover. I used to think a broken leg would almost certainly lead to a deer or moose being killed by predators. Perhaps it does in some cases, but not always.

I have encountered a number of both deer and moose with broken bones in the lower leg that have healed. Their bodies had laid down new bone tissue at the broken locations which then encased the broken ends and reinforced the bones. The additional tissue resulted in a larger diameter bone which then was quite obvious, even with the hide on the leg. Sometimes the broken ends healed in good alignment and sometimes they did not. See Photo No. 1 of broken and healed deer leg bones.

Broken and healed deer leg bones.

A particularly memorable incident was when a local deer feeder called to say a deer had just been killed in his front yard. When I arrived, he told me the history of that deer as he had known it since it was a fawn. One year it arrived for the winter with much of the hair missing from one side which was quite swollen (the swelling went away before spring). Another year it came in holding its jaw off to one side. He hand fed it alfalfa and wafers of sliced ear corn and by spring it was eating normally. He said it was the meanest doe he had ever known. How did it die? He saw it killed in a fight with another doe. Photo No. 2 shows the broken and healed jaw flanked by some of the broken and healed ribs.

 

LUMPY JAW

This is a condition found mainly in cervids and bovids and is caused by an anaerobic bacterial infection of the jaw, usually in the area of the molars. It most often affects the mandible, but it can also occur in the maxilla (upper jaw) and nearby tissues of the face. Often it is seen as an enlarged area of bone on the side of the jaw; other times it results in the loss of bone tissue of the jaw between or alongside of teeth which extends downward toward the bottom of the jaw. See Photo No. 3 for examples of both situations.

Cuts and abrasions of the lining of the mouth allow the bacteria to infect the wound. These can result from punctures by sharp food items, coarse foods becoming impacted between the teeth, even by the eruption of teeth (both the first set of teeth and their replacements). Several species of anaerobic bacteria can cause the infection, some of them are commonly found in the rumen. Bacterial by-products break down existing bone tissue and cause the growth of new bone which results in necrotic lesions of bone at the infected location.

Lumpy jaw in deer (top 2) and Moose (bottom).

These necrotic lesions are usually filled with a yellow to greenish pus which eventually breaks through and drains. The bacteria can be spread from one animal to another via infected saliva and draining pus contaminating feed and water. This can become a problem when animals, both wild and domestic, are kept in close association with each other such as commercial feed lots and artificial feeding stations for wildlife.

Left untreated, the damage to the jaw continually worsens, it becomes difficult for the animal to chew, and its physical condition deteriorates. Obviously, wild animals are not able to be treated as treatment often takes several applications. Domestic animals can be treated to kill the bacteria, but the existing damage will remain. Cattle are more often affected than are sheep and goats. Deer farms sometimes suffer significant losses of fawns from severe lumpy jaw infections.

CHEWING OF BONES AND ANTLERS

It is well known that rodents commonly gnaw on bones and shed antlers. Sometimes there is very little of either remaining. Finding one that has not been gnawed on by rodents can be unusual, unless it has been on the ground for only a short time. Carnivores regularly consume bones of their kills and probably of other bones they find.

Less widely known is that cervids, bovids, and a few other families of herbivores also chew bones and antlers. A study in the Cape Breton Highlands of Nova Scotia found that over 30 percent of shed moose antlers had been chewed on by moose within one month after snow melt. Other studies have found that bone and antler chewing by deer and elk occurs mostly during antler growth and mineralization for males and during lactation for females. This makes sense as these are the time periods when each sex is most in need of additional minerals to prevent or reduce osteoporosis.

Studies have linked the chewing of bones and antlers to the phosphorous content of the soil; low phosphorous in soil results in low levels of it in the plants that are eaten by animals. Excessive calcium, aluminum, or iron in the soil can reduce the availability of phosphorous to plants. Both situations can result in the need for a supplemental source of phosphorous.