THE RADIOGRAPHIC APPEARANCE OF CANINE CONGENITAL HYPOTHYROIDISM: SKELETAL CHANGES WITH DELAYED TREATMENT

Abstract

Congenital hypothyroidism was diagnosed in five Boxer dogs presented to the Veterinary Hospital of the University of Pennsylvania between 1978 and 1979. The dogs ranged in age from 5–19 months, and were from two unrelated litters. Congenital hypothyroidism was confirmed by serum T3 and T4 radioimmunoassay and TSH stimulation test. Serial radiographs made before and after L‐thyroxine oral supplementation were studied retrospectively to evaluate the resolution of skeletal abnormalities and to compare skeletal with chronological age. On initial presentation, all five dogs had the following skeletal manifestations of congenital hypothyroidism: short broad skulls, shortened vertebral bodies, and epiphyseal dysgenesis and delayed maturation. Epiphyseal dysgenesis was most common in the humeral (n = 3) and femoral condyles (n = 4), and proximal tibia (n = 4). Accelerated epiphyseal ossification occurred during thyroid hormone supplementation. Three dogs developed osteochondrosistype lesions. Bowing of the radius and disproportionate radius and ulna length resulted in humeroradial joint widening (n = 4) and humeroulnar joint subluxation (n = 1). Degenerative joint changes in the elbows (n = 4), stifles (n = 1), and shoulder (n = 1) were more common in the older dogs.