Metaphyseal osteopathy affecting the antebrachii was diagnosed in seven (five male, two female) captive bred cheetahs (Acinonyx jubatus) from four separate litters housed at two zoological institutions. Affected cheetah developed unilateral or bilateral forelimb lameness and valgus deviation of the fore paws between 6–10 months of age. Radiographic evaluation of both antebrachii was performed in all cheetahs. The principal abnormality was a core of lucent tissue in the distal ulna metaphysis, present bilaterally in six of the seven affected animals. Progressive cranial curvature of the distal radius and asymmetric thickening of the caudal cortex of the distal radius accompanied outward rotation and valgus displacement of the forepaws in each affected animal.
Hematologic and serum biochemistry parameters assessed in four animals were within normal limits for captive cheetah. Serum parathyroid hormone levels and Vitamin D levels were within normal ranges for domestic cats. A lesional biopsy from the distal ulna metaphysis of one animal revealed cartilage and osseus necrosis and metaphyseal dysplasia. Unilateral or bilateral ulna ostectomies were performed in all affected animals to correct the radial curvature and valgus limb deformity. The clinical signs and radiographic lesions evident in affected cheetahs resemble a poorly understood condition seen in rapidly growing large breeds of dogs termed retained enchondral cartilage cores.1 Possible etiologies for metaphyseal osteopathy in cheetahs include excessive dietary calcium supplementation, hypernutrition and a genetic predisposition in affected animals.
The authors thank Dr Helen McCracken for supplying historic records and radiographs from Melbourne Zoo.
1. Wisner, E. R. and L. J. Konde. 2002. Diseases of the immature skeleton. In: Thrall, D. E. (ed.). Textbook of Veterinary Diagnostic Radiology. W. B. Saunders Co. Philadelphia, Pennsylvania. Pp. 146–160.