independent

Saturday 25 October 2014

Hip Dysplasia a common problem in large breed dogs

Published 04/02/2014 | 05:42

Sasha, the Labrador pup was just six months old but she was gradually becoming less active when exercised, and in recent days, she had started to sit down in the middle of her walk. She put her rear end on the ground, and refused to budge. Was this psychological, or was there something wrong with the young dog?

I watched Sasha walking up and down our car park: she had an unusual gait, "bunny hopping" like a rabbit, moving both back legs together. I examined her back legs. When I moved her hip joints, she yelped and looked sadly at me. This was definitely the area of concern: I admitted her to our hospital to take x-rays.

Half an hour later, my suspicions were confirmed: Sasha's hips were the source of the problem. On the xrays, I could see the silhouettes of her hip joints. Each joint is meant to look like a ball-and-socket, like the connection point between a car tow bar and a trailer. Sasha's hip joints were far too shallow, more like a saucer shape than the deep cup of a normal hip socket. And the top of her thigh bone (the piece of the leg that slots into the hip socket) was square shaped rather than spherical. Sasha was a classic, dramatic case of Hip Dysplasia.

This severity of her problem was confirmed when I manipulated her hips under anaesthesia. Her hip joints were so loose that I could pull them right out of their sockets with ease. In a normal dog, the hips are so tight that this is impossible to do.

Hip Dysplasia is a common problem in large breed dogs. It's passed on from parents to offspring, although the precise mechanism of inheritance is complicated. Ideally, breeding dogs should have their hips checked by xray assessment before breeding from them. Each hip is given a number representing the quality of the dog's hips: this is known as the "hip score". If a dog has a bad hip score, breeding should be avoided, to prevent the creation of puppies with hips like Sasha. I was not surprised to hear that Sasha's parents had not been hip-scored.

The precise details of the disease process are still not clear. The main problem is excessive laxity of the hip joint, so that the two sides of the joint are not held closely together. This then creates a second problem, with the two sides of the joint not forming properly, so that they have a misshapen, irregular outline. The two aspects of Hip Dysplasia feed one another. The laxity of the joint stops the normal bones from developing, and the abnormal bone outlines prevent the joint from fitting tightly together.

Pups like Sasha may have apparently normal hips at birth: a combination of genetic, hormonal and environmental stresses cause too much looseness in the developing joint, and the problem gradually gets worse. Owners often don't notice any problem until the pup is six months old, but it just gets worse from there. The deteriorating condition of the joint is aggravated by the increasing weight of the growing dog, putting more pressure on the wobbly joints. And then arthritis starts to develop, with painful inflammation caused by the mismatch between the two joints surface. Some dogs are unable to walk by their first birthday.

Only a minority of cases are as bad as Sasha: more often a dog will just be mildly lame until they reach middle or old age, when arthritis of the hips begins to kick in. The painful creaky hips of older large-breed dogs such as Retrievers, Labradors and German Shepherds are often caused by Hip Dysplasia.

In mild cases, simple treatment can be enough to control the signs of discomfort, with a combination of pain relief, medication to improve the quality of the joint surfaces, and physiotherapy to improve the musculature in the hip area. Some dogs need this type of treatment as they mature from adolescents into adult dogs, and they can then be fine without further treatment until the later years of their life.

In severe cases, like Sasha, surgical intervention is needed. The "budget" option (which may still cost €1000 or more) is to remove the head of the thigh bone, so that the joint is removed, and the top of the thigh bone nestles into muscle rather than that painful bone-to-bone connection.

This method can be effective for smaller animals, but for big dogs like Sasha, there is really only one good answer: Total Hip Replacement. This is similar to the same operation in humans: the hip joint is sawn out of the body, and replaced by an artificial one. It costs €2500 or more per hip, but sometimes it's the only alternative to euthanasia.

Luckily, Sasha's owners had insured her as a young pup. The insurance company agreed to foot the bill, so she was referred to an orthopaedic specialist to have two new hips installed. I saw her again six months later and all is well. She no longer bunny-hops, and she now loves her walks.

Her owner has also had her spayed: there's no way that a dog with this degree of abnormal hips should be allowed to pass the problem on to the next generation.

If anyone out there is considering buying a large breed of puppy, don't forget to ask this question to the breeder: "Were the parents hip scored?". If the answer is no, move on.

Wexford People

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