Comparison of estimates of hip dysplasia genetic parameters in Estrela Mountain Dog using linear and threshold models

¹ Departments of Animal Science-CECAV, University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal
² Departments of Veterinary Science-CETAV, University of Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal
³ Departments of Clinic-CIISA, Faculty of Veterinary, 1300-477 Lisbon, Portugal

^* To whom correspondence should be addressed. E-mail: asilvest{at}utad.pt.

	Abstract

Genetic parameters, breeding values, and genetic trends of hip dysplasia in Estrela Mountain Dogs were estimated using linear (LM) and threshold (TM) models. A database with 313 animals was used. Right and left hip joints were individually scored, according to the Fédération Cynologic Internationale grading rules of the canine hip dysplasia system, as normal (1), borderline (2), slight (3), moderate (4) and severe (5 and 6). The estimate of repeatability was lower in LM (0.86) than in TM (0.90). The same tendency was verified with the heritability, since its estimate in LM was 0.38 and in TM was 0.43. However, these results do not establish any statistical differences between models. The genetic trend of canine hip dysplasia for LM and TM shows similarity in shape but considerable individual differences were found in EBV ranking lists. Therefore, the selection of breeding animals will not be the same with the two methodologies. In order to select the best method for genetic evaluation of hip dysplasia, further studies using more data and other dog breeds are required.

Key Words: dog, genetic parameters, hip dysplasia, linear model, threshold model