Condrodisplasia em ovinos deslanados no Nordeste do Brasil.

Abstract

The chondrodysplasias are diseases of the skeleton of different animal species. Affected animals are generally characterized by dwarfism and short heads. The disease is commonly hereditary, caused by a defect on the ephyphiseal cartilages that prevent normal bone growth. This dissertation is formed by two papers. The first is a review on osteochondrosis in domestic animals, mainly livestock. The second paper reports a new form of chodrodysplasia in sheep affecting Brazilian hair sheep of the Cabugi breed, also known as “cara curta” (short head). This breed is characterized by short head and sometimes the animals are slighter smaller and more compact that animals from similar breeds. Dwarf lambs that died in 2-6 months after birth are frequent in this breed. In a flock of 68 ewes and three rams of the Cabugi breed, 134 lambs were born during four years. From these 14 (10.4%) had marked dwarfism and died or were euthanized, 43 (32%) had a normal face, and 77 (57.5%) had the short face characteristic of the Cabugi breed. Dwarf lambs were much smaller than normal, with short legs, a domed head with retruded muzzle and slightly protruded mandible, sternal deformities and exophthalmic eyes situated more lateral in the face than normal. Four dwarf lambs were euthanized and necropsied and one was necropsied after the spontaneous death. Histological examination of the long bones of the limbs, bones of the skull base, and vertebrae showed no histological lesions. Four dwarf lambs and a control lamb were macerated for bone measurements. The biometric data showed that affected lambs have a disproportionate dwarfism with marked shortening of the skull and limbs ranging from 24% to 75% of the normal size (control lamb). It is suggested that the disease, is a hereditary chondrodysplasia caused by a recessive gene; homozigotes have marked lethal dwarfirm, but the disease is also partially expressed in all animals with the characteristic short face of the Cabugi breed, which are in heterozygotes.