PennHIP - the new testing scheme for

Canine Hip Dysplasia

Joe Fox MRCVS

What is hip dysplasia?

Canine Hip Dysplasia (CHD) is a hereditary condition that afflicts millions of dogs every year. It is an abnormal development of the hip socket that can eventually lead to crippling lameness and painful arthritis of the hip joint.

The occurrence of hip dysplasia is well documented in the large and giant breed dogs, but there is also evidence that it is prevalent in many small and toy breeds.

Many breeders will have their dogs assessed for hip dysplasia before they consider them for breeding, and potential puppy owners should ask the breeder for the 'hip score' of the parent dogs to indicate the puppy's likelihood of developing hip dysplasia. By not breeding from dogs with looser hips than the breed average, we aim to reduce the occurrence of hip arthritis problems.

What is PennHip?

PennHip is a hip laxity measurement scheme developed at the University of Pennsylvania. It is the only satisfactory measurement scheme for hip laxity (looseness of the hip joint) which is the most important factor in developing hip osteoarthritis. PennHIP testing involves 3 x-rays of the hips in different positions to measure the hip laxity (see below).

Before the PennHip scheme was developed, assessing a dog's likelihood of having hip dysplasia relied on the BVA scheme which looks at current osteoarthritis in the hip joint. (Osteoarthritis occurs as a result of hip laxity.) However, the onset of osteoarthritis can vary over time in affected dogs. For example, if a dog is x-rayed at one year old and the x-ray shows no osteoarthritis, there is still no indication of the dog's risk of developing hip osteoarthritis in the future as hip laxity has not been measured.

PennHip gives a consistently repeatable measurement of hip laxity. In other words if a dog was measured at yearly intervals, an almost identical laxity would show each time. What's more, with the PennHip scheme, we can tell from a very early age (as young as 16 weeks) a dog's propensity to develop hip osteoarthritis in the future. A breeder or pet owner can then make a judgement on whether a puppy will be suitable for breeding or whether the puppy should just be kept as a pet.

This radiograph shows the hips in an extended leg view to highlight current osteoarthritis. No arthritis is revealed, which means the hips are in good condition at the moment.

This radiograph shows the hips sitting snug in the sockets, where they should be.

This radiograph shows the hips when they are distracted out of their sockets and these hips are much looser than they should be. This means he is very likely to develop hip osteoarthritis in the future and also means he shouldn't be bred from as he is likely to pass this on to future generations.

This is the benefit of the PennHIP method - it shows what the hips are like now, but also tells us how likely the dog is to suffer hip problems in the future.

How do I arrange to have my dog tested?

The first thing to do is call our Whitchurch hospital on 01275 832410 and book an appointment for a free pre-PennHip check with Joe Fox MRCVS, our PennHip certified vet.

Joe Fox will talk you through the scheme and then arrange a suitable date for the x-rays to take place. (Please note that your dog will need to be anaesthetised as the x-rays require perfect positioning of the hips for accurate results).