Carnivorous Cervids—aka bone munching deer

Figure 1

In July, a mule deer doe (Odocoileus hemionus) was euthanized by Alberta Fish and Wildlife due to poor body condition and hemorrhagic diarrhea. At the time of euthanasia, a hard swelling was noted on the right side of the face (Figure 1).

Figure 2

At necropsy, this animal was confirmed to be in poor nutritional condition with marked loss of muscling and internal fat stores. She was also observed to be actively lactating. Removal of the skin over the jaw revealed a hard tan object ~15 x 10 x 10 cm that was tightly impacted at the back of the jaw and embedded onto the molars (Figure 2).

Figure 3

Figure 4

Closer examination of this object identified it as a piece of cancellous bone. Removal of the mandible revealed deep grooves within the bone made by the mandibular molars (Figure 3). This bone was easily removed from the teeth revealing similar groves on the other side (Figure 4) and deep pressure ulcers within the underlying gingiva and buccal mucosa (Figure 5)

Figure 5

The larger arteries of the head were carefully examined for arterial worms which were not observed, and sectioning of the underlying maxilla and mandible did not reveal evidence of infection within the bone. Bacterial culture of the intestinal content grew Clostridium difficile, and an acute hemorrhagic enteritis was confirmed microscopically. This deer was negative for chronic wasting disease through testing of the obex and retropharyngeal lymph nodes. In this case, poor nutritional condition likely occurred due to impaired ability to prehend and masticate food as a result of the impaction. Clostridial enteritis likely occurred secondary to the resulting debilitation. Other causes of facial masses and feed impactions including lumpy jaw (bacterial infection of the bone with Actinomyces bovis or other anaerobic bacteria) or arterial worms (Elaeophora schneideri) were ruled out.

Bone eating, or osteophagia, has been previously reported in a variety of cervid species and is hypothesized to occur in response to deficiencies in certain minerals including magnesium, phosphorus, sodium, potassium and proteins (1,2). Mineral deficiencies may occur more commonly during antler growth or lactation. The liver of this deer was tested for magnesium, manganese, iron, cobalt, copper, zinc, selenium, and molybdenum, which were within normal limits. Unfortunately, we were unable to test for other potential mineral deficiencies in this case. Interestingly, deer species have also been reported to occasionally eat baby birds from nests. Again, this is hypothesized to be a response to underlying mineral deficiencies (3).

1. Barrette C. 1985. Antler eating and antler growth in wild Axis deer. Mammalia 49(4).
2. Estelles-Domnigo, I. et al. 2022. Scavenging behaviour of red deer Cervus elaphus Linnaeus, 1758 (Artiodactyla: Cervidae) in Eastern Spain. Acta Zool. Bulg. 1-3.
3. Furness RW. 1988. Predation on ground-nesting seabirds by island populations of red deer Cervus elaphus and sheep Ovis. Journal of Zoology. 216:565-573.

Submitted by Dayna Goldsmith, CWHC Alberta in collaboration with Alberta Environment and Parks and the Diagnostic Services Unit