Tonight at KCC we had some great classic cases, including one of osteochondrodysplasia in a Scottish Fold cat. The cat presented was skeletally mature, and lame in the hind limbs. Radiographs of the tarsi showed extensive periosteal new bone formation, which was more apparent on the lateral side. There were also large exostoses arising from the calcanei. All of the lesions were smoothly marginted and lobular in appearance. The lateral radiographs of the forelimbs were normal, but there was mineralization in the intervertebral foraminae of the lumbar spine.
Scottish Fold osteochondrodysplasia is a disease seen in homozygous and heterozygous carriers of the Scottish Fold gene. There is a defect in enchondral ossification which results in altered metaphyses and widened physes. The result is misshapen carpal and tarsal bones, shortened distal extremities, and widened endplates of tail vertebrae. The abnormal ossification of metaphyses alters the joint mechanics, and leads to secondary degenerative joint disease. Other features include osteopenia of surrounding bone, and exostoses plantar to the calcaneus. Homozogous cats develop the disease earlier than heterozygous cats.
This type of case is a diagnosis based on characteristic apearance and signalment. You could have other differentials on your list, but osteochondrodysplasia should be the top one by far. Additional images to ask for would be opposite limb, forelimbs, and lumbar spine and tail to complete your evaluation.
1. Hubler M, Volkert M, Kaser-Hotz B, et al. Palliative irradiation of Scottish Fold osteochondrodysplasia. Veterinary Radiology & Ultrasound 2004;45:582-585.
2. Malik R, Allan GS, Howlett CR, et al. Osteochondrodysplasia in Scottish Fold cats. Aust Vet J 1999;77:85-92.
3. Partington BP, Williams JF, Pechman RD, et al. What is your diagnosis? Scottish Fold osteodystrophy. J Am Vet Med Assoc 1996;209:1235-1236.