Hip dysplasia as threshold genetic disease in dogs. Incidence and predisposition in three Hungarian shepherd breeds

Abstract

This dissertation is a prospective study of a large group of privately owned dogs of three Hungarian shepherd breeds. The dissertation provides an overview of the current understanding of canine hip dysplasia, it highlights the characteristics and latest research within this field. It explains the methods of early detection of inherited genes as well as the ways to prevent the disease from developing in future breeding dogs. The data analysis evaluates the various aspects of the Norberg angle in three Hungarian dog breeds: Mudi, Pumi and Puli. In addition to this it presents the incidence, level of hip dysplasia (HD) and the predisposition in the mentioned breeds in relation to influencing factors such as gender, age, kennel, breed, owners gender, location code and year of birth. The investigation showed that in Mudi, Pumi and Puli the incidence of hip dysplasia is highest in category “A Free”, where 23 Pumi, 98 Puli and 41 Mudi dogs were categorized. This equates to 32%, 50.7% and 64% respectively. Dogs grouped as borderline (B) were 15 Pumi, 47 Puli and 14 Mudi, thus 20.8%, 24.3% and 21.8% accordingly. This decreasing trend of HD incidence continued with 29.2%, 16.5% and 4.7% of the dogs being regarded as mildly (C) affected, 15.3%, 6.2% and 4.7% classified as moderately affected and with 2.7%, 2% and 4.7% of the dogs regarded as severely affected. This showed that Pumi was the upmost-predisposed breed out of the three. When comparing the expected and observed values of level of HD, the difference between expected and observed values showed that 4 out of 5 levels of HD were statistically significant. Thus, for category B, C, D and E there was a high discrepancy between the expected and observed values, indicating that observed values (obtained by veterinarians and clinicians) tended to underestimate the actual severity of the various levels of HD. In all conclusion: there were no significant impacts on the Norberg angle found in our data set, with the exception of breed and kennel. None of the three Hungarian shepherd breeds are significantly more or less predisposed to HD than any of the other small and large breeds. We confirmed that environmental factors like kennel, thus feeding, raising and keeping conditions adds to the already predisposed dog and makes the manifestation of the disease even more unpredictable.