Heritable bone fragility, joint laxity and dysplastic dentin in Friesian calves: a bovine syndrome of osteogenesis imperfecta.

A lethal syndrome of bone fragility, joint laxity, translucent teeth and other connective tissue defects occurred in Victoria in 37 of 84 progeny of a clinically normal, registered Friesian bull between 1978 and 1981. Test matings to unrelated cows indicated that the syndrome was transmitted as an autosomal dominant trait. Affected calves were readily recognized at birth by pink teeth and abnormal posture. At birth 14 of 19 affected calves examined had rib fractures and 4 of these calves also had fractures of long bones. Spontaneous fractures of long bones also occurred in 5 of the 11 calves which survived for more than 10 days. Hypoplasia of dentin, tendons, and ligaments were observed in all cases at necropsy. Osteopenia was only observed at necropsy in older calves. Histological lesions of bone and teeth were similar to those reported in descriptions of osteogenesis imperfecta with dentinogenesis imperfecta in man. The syndrome is provisionally designated as "bovine osteogenesis imperfecta". Semen has been collected from the progenitor bull to enable further investigations of this heritable collagenous tissue dysplasia.

Brachygnathia superior and degenerative joint disease: a new lethal syndrome in Angus calves.

Brachygnathia superior and generalized diarthrodial degenerative joint disease were seen in 17 related, purebred Angus calves ranging in age from 2 days to 4 months. Craniometrical studies revealed decreased maxillary and palatine bone lengths and increased cranial, skull, and facial indices. Radiological evaluation of major appendicular joints demonstrated lipping of the joint margins with osteophyte formation, sclerosis of subchondral bone, and narrowing of joint spaces. Synovial fluid evaluation indicated joint degeneration but no etiologic agent. Rheumatoid factor analysis of plasma was negative. Grossly, all major appendicular joints were defective including the atlanto-occipital articulation. Lesions ranged from loss of surface luster to erosions and deep ulcers with eburnation of the subchondral bone and secondary proliferative synovitis. Histological changes were degeneration of the articular cartilage matrix, chondrocyte necrosis, flaking and fibrillation, chondrone formation, erosions and ulcers of the articular cartilage with subchondral bone sclerosis, vascular invasion with fibrosis, and chronic, nonsuppurative, proliferative synovitis. Growth plates had defective chondrocyte proliferation and hypertrophy with aberrant ossification of calcified cartilaginous matrix. Histochemical analysis of cartilage and bone failed to incriminate which component was defective, glycosaminoglycan or collagen, but indicated different distribution or absence of one or the other. Genealogic studies revealed a genetic basis for the new defect.