Mandrill Bone Pathologies

Author: A. Taivalkoski

One of the specimens in ZAG’s collection (UBZAG 10) was an older mandrill (Mandrill sphinx) who had to be put down due to old age. This specimen had numerous pathologies present on its skeleton. A number of the joints had severe arthritis resulting in bone loss and eburnation in the long bone epiphyses.¬†¬†Additionally, large portions of the vertebrae were fused together.

Eburnation on articular surface of ulna, pitting, and osteophytes (bone spurs)
Eburnation on articular surface, pitting, and osteophytes (bone spurs)

Arthritis destroys cartilage in the joints and in the later stages of this disease, the cartilage may be completely worn away. This can cause the bones that make up the joint to rub directly against each other. This causes the articular surfaces to have a polished, shiny look as in the photo of this mandrill’s ulna above.

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Pitting and osteophytes characteristic of arthritis present on calcaneus
Pitting and osteophytes on humeral head

Arthritis causes pitting of the bone surface. In response to this bone deterioration, the bone begins to form new bone that presents as bony spurs often along the margins of the bone joint (osteophytes).

Arthritis does necessarily affect the joints on both sides of the body evenly. This can be seen in the picture of the left and right femurs below. The left femur does not exhibit evidence of the advanced stage of arthritis, unlike the right femur which has severe pitting and osteophyte formation.

Comparison of non-arthritic femur (Left) and arthrits affected femur (Right)
Comparison of non-arthritic femur (Left) and arthrits affected femur (Right)

In addition to severe arthritis, this animal also had fusion of the vertebrae all along its spine.

Bridging and fusion along posterior surfaces of cervical vertebrae

Bony bridges have formed between all of the cervical vertebrae, causing partial to complete fusion. This pathology is present all along the animals spine, from the cervical down to the lumbar vertebrae. This would have caused the animal to have a very limited range of movement along its spine.

Bridging and fusion of lateral surfaces of cervical vertebrae


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