The utilization of the Vezzoni modified Badertscher distension device in breeding programs: Heritability estimates and effect on the hip dysplasia prevalence

Canine hip dysplasia (CHD) is a common orthopedic condition, influenced by both genetic and environmental factors. While current breeding programs often rely on ventrodorsal hip-extended (VDHE) radiographs, it is known they fail to accurately assess hip joint laxity. Therefore additional laxity-oriented diagnostic techniques have been developed. This study aims to evaluate the effectiveness of the Vezzoni modified Bädertscher distension device (VMBDD) technique, which quantifies hip joint laxity with the laxity index (LI), as a screening tool in two breeding programs. Data from a Belgian population of assistance dogs (population A) and a French population of guide dogs (population B) were analyzed. The heritability estimates of the LI, estimated using Bayesian statistical methods, were high in both populations (0.83 in population A and 0.82 in population B). Improved screening of parents by combining the VMBDD technique with the VDHE, significantly decreased LI and the prevalence of CHD in their offspring. In population A, when two parents were screened with the VMBDD compared to one, there was an average LI decrease of 0.03 (P<0.05). In population B, when one or both parents were screened with the VMBDD compared to none, the average LI decrease was 0.04 (P< 0.05) and 0.05 (P<0.01), respectively. In population A, screening both parents with the VMBDD in addition to the VDHE, resulted in 82.7% (P< 0.05) lower odds of CHD compared to screening only one parent. In population B, screening one parent led to 72.3% (P<0.05) lower odds of CHD compared to none of the parents being screened. In population B, when both parents were screened with the VMBDD, not a single case of CHD was observed in the puppies. In conclusion, based on these results, the VMBDD technique has the potential to drastically reduce CHD prevalence and is as such an excellent tool for breeding programs.