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Condrodisplasia tipo Dexter em fetos bovinos abortados / Chondrodysplasia Dexter type in aborted bovine fetuses

Wurster, Fabiana; Bassuino, Daniele Mariath; Juffo, Gregory Duarte; Boos, Gisele Silva; Boabaid, Fabiana Marques; Antoniassi, Nadia Aline Bobbi; Driemeier, David.
Acta sci. vet. (Impr.); 40(3): Pub. 1060, 2012. ilus
Artigo em Português | VETINDEX | ID: biblio-1373717

Resumo

Background: Chondrodysplasia is a congenital anomaly related to defects of the genes that control the chondrogenesis. This anomaly is described in many breeds of cattle and consanguineous matings increases the likelihood of developing defective traits. There are three distinct syndromes known: Dexter, Telemark and Brachycephalic type. The chondrodysplasia Dexter type syndrome is associated to an incompletely dominant gene, which occurs in Dexter and Holstein breeds more frequently, yet Charolais and Jersey can also be affected. There are three recognized phenotypes in this form of disease: severe achondroplasia, with abortion before the seventh month of gestation (monster Dexter), when related to dominant homozygous; chondrodisplasia with limbs shortening, when heterozygous; and normal animals, when recessive homozygous. The objective of this paper is to describe Dexter chondrodysplasia observed in two bovine fetuses examined by the Setor de Patologia Veterinária from Universidade Federal do Rio Grande do Sul (SPV-UFRGS). Case: The necropsy of two aborted bovine calves was performed by the SPV-UFRGS. The Fetus 1 did not have data, neither clinical history. The Fetus 2, a Jersey breed calf, was in the last third of gestation and came from a property with Jersey and mini-Jersey herd. Natural mating was used for reproduction, with only one bull. Macroscopic alterations observed in both fetuses were characterized by shortened limbs, rounded and disproportionate skull, short snout, undershot jaw, tongue protrusion and abdominal hernia with eventration. In the second fetus was also observed spina bifida and palatoschisis. Microscopically, in both fetuses were observed extensive areas of immature cartilage, chondrocytes of the femur's bone tissue were not organized in recognizable growth plates, the metaphysis was markedly shortened and consisted in short bone trabeculae with occasional cartilage isles. Immunohistochemistry (IHC) to detect bovine viral diarrhea virus (BVDV) was negative. Discussion: The macroscopic and microscopic alterations in both fetuses were compatible with chondrodysplasia "monster Dexter" type. Such alterations, associated with dominant homozygotes, are due to defective endochondral ossifi cation with little growth in the length of long bones, meanwhile intramembranous ossification beneath the periosteum keeps growing and contributing to the abnormal volume and growth of the bones. Such difference is clearly observed when the size of the head is compared with the rest of the body. As the skull bones depends basically on intramembranous ossification, they are generally bigger than the rest of the body. The negative result of IHC to BVDV shows that this agent, known as the cause of congenital malformation did not have association with the anomalies observed. According to other researchers, this low frequency of viral agents as responsible for congenital anomalies was observed previously in cattle from the south of Brazil. Although Dexter chondrodysplasia can be considered of occasional occurrence, it can be responsible for considerable damage. As an abnormality with hereditary nature and consanguinity is the main reason to its occurrence, prevention is the main method to be adopted by the producer to avoid bigger loses.
Biblioteca responsável: BR68.1