Hips that make them hop: A blog about canine hip dysplasia

While hip dysplasia sounds a bit foreign and scary, it is surprisingly common in our four legged friends. Whether the vet has diagnosed your own dog with it, you’ve heard whispers at the dog park, heard echoes of “hip scores” when looking at puppies, or done some googling when your dog starts moving oddly… you’ve probably heard of it. But what actually is it? What causes it? And, most importantly, what can we do about it?

PATHOLOGY 

Canine hip dysplasia is a developmental disorder that results in abnormal skeletal anatomy of the hip joint. So, in simple terms, as the hip grows and develops something goes wrong and the hip ends up abnormally shaped. The hip is a ball and socket joint, so the rounded head of the femur should sit nice and deeply in the socket formed by the pelvis. This gives the hip a lot of stability, though less mobility than a joint like the shoulder. The skeletal changes of hip dysplasia causes the head of the femur to sit less snugly in the socket. In extreme cases of severe hip dysplasia, the ball may have very little coverage from a pathologically shallow socket. With reduced bony stability that the socket provides, the joint is lax leading to altered biomechanics and microtraumas to the joint and surrounding tissues. Pain often occurs when the head of the femur (the ball) hits the rim of the socket. The change in biomechanics and the resulting microtraumas can then cause bony growth and changes, and lead to osteoarthritis. 

Cause/Risk Factors:

• Genetics

• More common in large breeds; German Shepherds, Labradors, Golden Retrievers, Rottweilers 

• Inadequte nutrition

• Obesity 

• Growth rate 

• Excessive exercise

Signs and Symptoms:

• Lameness of the hind legs 

• Reluctance to exercise

• Difficulty getting up from sitting or lying 

• “Bunny hopping” gait- moving both hind legs together

• Excessively swaying pelvis side to side when walking

• Painful behaviours- check out our blog here for further information

• Differences in muscle size/shape from one side to the other

Diagnosis and Grading:

To diagnose your dog, your vet will start by evaluating their gait and feeling the way their hips move. If they suspect hip dysplasia, your vet may recommend X-rays in order to confirm and grade a hip dysplasia diagnosis.  Dogs are graded from A-E.

• A: No signs of hip dysplasia

• B: Near normal/ borderline

• C: Mild hip dysplasia

• D: Moderate hip dysplasia

• E: Severe hip dysplasia 

In mild cases of hip dysplasia, there are mild inconsistencies in the articulation between the ball and the socket, such as the socket being slightly flattened. In a severe case, the hip may be dislocated, with marked anatomical abnormalities and osteoarthritic changes.

Your vet may also provide a PennHIP distraction index score which sits between 0-1. This is a set of 3 x-rays that look at the laxity within the joint. When the score is near zero, it signifies minimal joint laxity, meaning the hips are nice and tight. Conversely, a score approaching 1 reflects significant looseness within the joint. Generally, pups with tighter hip joints face a much lower risk of developing dysplasia and/or osteoarthritis compared to those with more laxity.

If you are looking at purchasing a breed of puppy with an increased risk of developing hip dysplasia, some breeders will provide PennHIP scores, as this test can be completed from 16 weeks old. So, it is always worth asking! 

Home Management:

 So, what can you do? There are a few simple steps you can take to minimise the effects or progression of hip dysplasia. Making sure your dog remains a healthy weight minimises the stress put through the hip joint whenever your dog is weightbearing. It might be tempting to minimise exercise as well, but low-impact activities like walking and swimming are important to keep the joints healthy and the muscles supporting the joints strong. We recommend avoiding playing fetch, due to the stress jumping and sudden stops/turning can put on the joints. If you have a puppy, we also recommend making sure that their exercise routine is appropriate for their level of growth (for example, no running with you until at least a year!). Jumping up and down puts more load on the hind legs, so consider how you can avoid things like jumping on and off furniture or in and out of the car. If lifting them isn’t an option, perhaps a step or a ramp! Finally, make sure your dog has a soft, comfortable place to rest.

Vet Management: 

Your vet’s treatment suggestion will be individualised to take into consideration your dog's condition, age, activity level, and comorbidities. If there are signs of pain, your vet may recommend a short or long term course of pain relief, often anti-inflammatories. Dietary supplements such as omega-3 fatty acids can help to maintain joint and cartilage help and can be easily added into your dog’s diet. In some cases, your vet may recommend a course of injections to help support joint health, such as Cartrophen. These are disease-modifying medications  that work by addressing the symptoms of osteoarthritis like cartilage breakdown, rather than just relieving pain. In severe cases, surgery may be the best option for your pet. More commonly, a Femoral Head and Neck Ostectomy (FHNO) or a Total Hip Replacement (THR) are used to address severely dysplastic or osteoarthritic hips. The FHNO involves the removal of the hip “ball”, and allowing scar tissue to form a “false joint”. Meanwhile, a THR replaces the arthritic joint with a prosthesis. As a THR mimics the original joint biomechanics, it is more likely to produce near-normal hip function after recovery, but is more expensive and has a higher risk for complications. Risks tend to be lower for a FHNO, but function is often impacted long-term. However, these impacts can be minimal, particularly when managed correctly. Usually, smaller dogs are often recommended to undergo a FHNO and adapt well to the changes, whereas larger breeds are often recommended a THR. 

Physiotherapy Intervention

The first role your physiotherapist will play is working alongside your vet to assist with pain relief for your pooch. In the physio clinic, this can mean utilising treatment options such as laser, massage, PEMF and TENS. Once we get the pain under control, we want to get your dog moving, and get them strong. Stretching, strengthening exercises, and hydrotherapy are all useful tools in getting your dog feeling their best. Movement in the pain-free range keeps the joint mobile and healthy, encouraging synovial fluid production and nutrient exchange- essentially keeping the joint “oiled”. Stronger muscles support the joint, helping absorb force and stabilising from excessive movement. By using our underwater treadmill, we can build muscle by having the dog push against the water, whilst unloading the potentially painful joint by using the buoyancy of the water. 

So, if you notice your dog hopping or limping, or looking a bit uneven behind, get them checked by your vet! Now you know all about hip dysplasia you’ll be cool, calm and collected if that diagnosis comes back and ready to tackle it with ease… and ask for a referral to your friendly local vet physio of course!