Segregation Analysis of Canine Hip Dysplasia in Cane Corso Italiano Dogs

Canine hip dysplasia affects dogs of all breeds, and is the most frequent orthopaedic disease in large and giant breed dogs. Radiology has commonly been used for diagnosis of CHD. Three somewhat different international scoring methods were developed. The Federation Cynologique Internationale (FCI), the Orthopaedic Foundation for Animals (OFA), and the British Veterinary Association/Kennel Club (BVA/KC) methods. Details of 3 different scoring systems were described by Flückiger [1]. The FCI scoring method is used in member countries of FCI (most European countries, Russia, South America, and Asia), the OFA method is used exclusively in USA and Canada, and the BVA/KC method is used in Great Britain, Ireland, New Zealand, and Australia.

In consequence of the major progress in the detection of genes responsible for CHD [2-7], many investigators have suggested the implementation of estimated breeding values (EBV) to improve the selection [8-13]. Phenotypic screening of joint conformation remains a currently available strategy for breeders to make selection decisions. The present study [14] showed the efficiency of employing phenotypic selection on breed improvement of CHD and canine elbow dysplasia in 60 dog breeds. A similar effect of phenotypic selection was described in the past [15,16]. The Cane Corso Italiano (Figure 1) is a new dog breed that was fully recognized by FCI in 2007. Results of the first investigation of this breed were described by Korec et al. [17]. The current paper describes for the first time the Cane Corso Italiano segregation analysis of CHD, and suggests a simple method that can be used by breeders for selection, that would enable a reduction in the prevalence of CHD in offspring.

Data collection

Data was obtained from 1813 CHD scored dogs, using the Cane Corso Italiano Pedigree Database (www.canecorsopedigree.com). FCI official guidelines were used for scoring CHD.

Figure 1: Photograph of a Cane Corso Italiano dog (Koleta Atison, Evžen Korec’s archive).

Figure 2: Parental crosses male CHD-A x female CHD-A.

Figure 3: Parental crosses male CHD-B x female CHD-B.

Offspring segregation of CHD from parental crosses containing parents’ CHD combinations between CHD scored A, B, and C were analyzed. Results are summarized in Figure 2-7. Offspring segregation of parental crossing (male A x female B) was compared with reciprocal crossing (male B x female A).

Figure 4: Parental crosses male CHD-C x female CHD-C.

Figure 5: Parental crosses male CHD-A x female CHD-B, male CHD-B x female CHD-A.

Figure 6: Parental crosses male CHD-A x female CHD-C, male CHD-C x female CHD-A.

Figure 7: Parental crosses male CHD-B x female CHD-C, male CHD-C x female CHD-B.

Most (59.9 %) of CHD-A scored offspring arose from male CHD-A x female CHD-A crosses, 50.0 % CHD-A offspring arose from male CHD-A x female CHD-B crosses, and 47.1 % CHD-A offspring arose from male CHD-A x female CHD-C. Only 35.3 % CHD-A offspring arose from male CHD-B x female CHD-B crosses, and 16.7% CHD-A scored offspring arose from male CHD-C x female CHD-C crosses. Interesting, and for breeders valuable, is our finding that male CHD-A x female CHD-C crosses or reciprocal crosses of male CHD-C x female CHD-A enable substantially more CHD-A scored offspring, compared to male CHD-B x female CHD-B crosses.

These results suggest that some dominant gene or genes are responsible for the CHD-A phenotype. Reciprocal crosses gave approximately same offspring segregation of CHD. Minor differences are probably caused by the fact that also environmental (not only genetics) factors influence the CHD-score. The genes responsible for the CHD-status are probably located on the autosomes. Our results suggest that the optimal breeding programme for the reduction of the prevalence of CHD should employ crosses of males and females that are both CHD-A scored. Breeders should regularly realize these crosses, rarely crosses of one parent CHD-A scored and second CHD-B scored, and exceptionally crosses of one parent CHD-A scored and second CHD-C scored. Responsible breeders should exclude all crosses of both parents worse than CHD-A scored. The main pedigreed breeding males should only be CHD-A scored.

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