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What is Hip Dysplasia?
Hip Dysplasia (HD) is the abnormal formation of the hip joint. The ball and socket joint in the hip is not formed correctly, leading to pain and arthritis.
Hip Dysplasia develops primarily in the first twelve months of age causing the ball and socket joints to be too shallow and this causes the femur (the thigh bone) to partially dislocate as the dog moves. The abnormal surfaces rubbing on the joint and associated friction causes painful osteoarthritic (bony) changes.
The severity of the effects vary significantly from mild symptoms to crippling lameness and pain. The age of onset of symptoms depends on a number of factors which will be described later.
Bilateral Hip Dysplasia in a dog
This means both sides are affected by HD. You can see especially on the right of the x-ray, how the socket is very shallow, which causes the ball to partially dislocate.
What breeds are at risk?
The general rule is the larger the dog, the more at risk, although many breeds that are not classified as large breed can also be affected. They may not show as severe clinical signs because they are lighter. Although HD is an inherited condition, nutrition and environmental factors have an effect too. A dog that is of higher risk that is fed a suitable diet and has restricted exercise in its first 18 months (when the dog is still growing and the skeleton maturing) may have the level of damage significantly reduced.
How do I know if my dog has hip dysplasia?
Severely affected dogs may start showing hind limb lameness from as early as one year of age, while less severely affected dogs might not show signs until they are older. This is very dependent on the nutritional and environmental factors for the dog too. The earliest signs are often an increased reluctance to sit, not wanting to climb steps and appearing to be sore and painful when getting up after resting.
If your dog is showing any of these symptoms then they should be taken to your veterinarian for examination.
How do I reduce the risk of my dog having hip dysplasia?
Choose your puppy carefully. Especially if you are choosing a large breed pedigree dog, you should ask to see the hip scores of the parents and even the grandparents too if at all possible. The lower the number the better. Scores are given up to 53 on each side, which is reported as a maximum score of 106. A score of less than 5 is preferable, although for some breeds less than 8 is still considered to be acceptable.
As well as looking for a low total score, you should also look for scores that are similar on each side, i.e., both sides score as 2, giving a total of 4, rather than situations where one leg has a hip score of 0 and the other of 4.
If possible, ask to see older genetically related dogs to get an idea of how badly are they affected by arthritis if at all. Even if they have low hip scores they may still be prone to osteoarthritis. Viewing the older genetically related dogs gives an indication of how prone they are likely to be. Remember old age arthritis is common so don’t be too alarmed if 13 - 14 year old dogs are lame, however if one from a line with low hip scores is very lame at aged 6 or 7 years it would be cause for concern.
Because hip scores vary between breeds and some breeds have on average very high scores, it may not be possible to seek out puppies with very low scores. However you should seek out puppies from parents with scores below the breed average if this is the case.
Puppies cannot have their own hips scored until they are at least 12 months of age, so you have to rely on the parents' hip scores to give an indication of the offspring's likelihood of low hip scores. It is however possible to have good hip scores in the parents and still have offspring from those parents have poor hip scores.
Click here to see the latest hip score averages. When you review the hip score averages of each breed, remember that where small numbers of dogs have been screened in New Zealand, the average given in the document does not necessarily reflect the average for that breed in New Zealand. For example, only 2 Irish Water Spaniels have been hip scored, so the average may not be accurate for the breed. However when you look at the results for Labradors and German Shepherds, the average is far more reliable considering that over 1,000 dogs in each breed have been tested.
Remember hip dysplasia is not the only thing you should check in at-risk breeds. Other examples include Elbow Dysplasia (ED), Progressive Retinal Atrophy (PRA), congenital heart conditions, other eye diseases and many more. You should research the inherited diseases your chosen breed is at risk from and ensure that your puppy comes from good breeding stock.
Once you have chosen a puppy from a good breeding background, you need to feed it well. Premium brand puppy biscuits designed for the breed's size (for example, Large Breed Puppy Growth for large breeds like Labradors, Great Danes, German Shepherds etc) are formulated to ensure that they grow steadily, without growing too fast for their young, immature bones to cope with the weight. Your veterinarian can advise on the best diet. If you have spent the money and invested in a pedigree pup, invest in the best nutrition that you can.
This is the third component that is important in reducing the changes of hip dysplasia and is perhaps the area that is often overlooked by new owners who can’t wait to take their young pup running or let it tear around madly with other dogs. Your veterinarian will be able to give specific advice for the breed you have chosen, but generally if you have selected a large breed puppy you will need to be very careful with its exercise for the first 18 months of its life. This will give its bones a chance to mature, for the growth plates to close, and for the dog to become fully grown. This means minimise walking up and down steps, stairs or hills. If it must be done, encourage your pup to attempt these slowly and carefully. Keep walks gentle, not too long and not too exuberant so as to reduce stress on the soft young joints.
How is Hip Dysplasia diagnosed?
To confirm HD, your veterinarian would take radiographs (x-rays) of your dog’s hips once he or she has reached 12 months of age. To get an accurate hip radiograph, your dog would need to be fully anaesthetised. Radiographs taken for the scheme must meet specific criteria, and are sent off to a panel to be scored. If you were planning to breed from a large breed dog in particular, you would be well advised to get this done. This is the first step to take to ensure your dog is suitable for breeding. If he has a high hip score then you should avoid breeding from him, as it is essential we work together to improve the breeds' genetics. Secondly, potential purchasers of pups will want to know. In fact you should expect them to ask and if they don’t, you may question how much research they have done into owning a large breed puppy.
How is hip dysplasia treated?
Even with the best of research, you may still end up with a dog with hip dysplasia. There are a number of options depending on the age of the dog, severity of the symptoms and the budget of the owner.
Options include long term pain relief medications, corrective surgery to improve the depth of the joint (suitable only in young dogs with only early osteoarthritic changes) and even full hip replacement. Hip replacement is only offered by specialist referral centres and costs several thousand per hip, but the results (as with humans) are amazing. After studying the symptoms and signs on the radiographs, your veterinarian will be able to discuss with you the best options for the management of hip dysplasia.