Nutritional fibrous osteodystrophy with chondroid metaplasia in a Nile monitor, Varanus niloticus

Carnivorous reptiles are not usually thought of as being prone to metabolic bone disorders. A constant diet lacking in calcium or bone and/or high in phosphorus or low in vitamin D3 can lead to this nutritional disorder in certain situations. Nile monitor lizards are carnivorous lizards native to Africa and common in the pet trade and as display animals in zoos. They normally consume whole vertebrate prey but will readily take muscle and organ offerings. This is a case of a Nile monitor that suffered fibrous osteodystrophy and chondroid metaplasia after being fed mostly muscle tissue for over two years. Once the diet was corrected the clinical signs resolved.