Hip Joint Laxity in Small Dog Breeds A Radiological Study

Abstract

Open Access Research Article without osteoarthritis by stressing the joint with an exact amount of weight (12 and 20 kg) in dog breeds of small size. Material & Methods All dogs were euthanized due to other reasons than back and/or hind leg problems at the University Hospital for Small Animal with an overdose of barbiturate less than 20 minutes before the stress procedure were performed. All 55 dogs of 15 different breeds having a body weight of 16 kg or less and age from 3 to 14 years had their Coxo-Femoral joints radiographed in ventrodorsal projection in dorsal recumbence position (Siemens Polydores LX50, Fuci Film and 3M Trimax intensifying screens). The chest was fixed and tension was applied equally to each leg with a chain around the hocks connected to spring-loaded weight via a bar across both hocks. The dogs were radiographed, first with no tension on the hips figure 1 and then with tension (measured with the spring balanced weight) on both hind legs of 12 kg figure 2 and 20 kg Abstract The clinical and hereditary significance of laxity of the hip joints in dog breeds of small size is not earlier described. Joint laxity of the hip joints was measured in 55 dogs recently euthanised for other reasons than orthopaedic or back problems by distally drawing in the hocks with up to 20 kg to provoke laxity in the hip joints. Stress radiographs of the hips in the extended position were then taken at 0, 12 and 20 kg traction. Hip joints with any signs of osteoarthrosis on the radiographs were excluded from the study. The displacement index, I, was calculated as the displacement of the caput femoris from the cranial border of the acetabulum (d) divided by the radius of the caput femoris (r). The greatest laxity was found in the Dachshund having a mean I of 1.27 and the least laxity was found in Breton Basset dogs having a mean I of 0.25. There was no statistically significant in age, weight or sex related variation in laxity and little individual difference in displacement within the breeds but highly statistically significant effect of breeds (p < 0.0001) on I. Vacuum phenomenon was seen in distracted hips with high I. The study indicates that joint laxity can be present without clinical importance and not predispose for osteoarthritis in dog breeds of small size.