X-linked spondylo-epiphyseal dysplasia tarda in the Danish-Swedish farm hound.

In two litters from the same parents, three out of four males had an abnormally short leg and body length. Affected dogs showed signs of pain when moving, which could be eliminated by analgesia. On radiography, these animals had widened, radiolucent, irregularly bordered intervertebral disc spaces. When examined at seven months of age, the epiphyses appeared widened and irregular in shape and outline. General bone opacity in the vertebral column was lower in the affected male dogs than in the normal littermate. The affected dogs developed spondylosis and arthrosis of the larger limb joints. All affected dogs were euthanased on humane grounds, the eldest at the age of two years nine months. Based on the clinical and radiographic evidence, the condition seen in the male dogs described here resembles X-linked spondylo-epiphyseal dysplasia tarda caused by a collagenopathy due to malformation of COL2A1 as seen in human beings.