What Is Hip Dysplasia In Dogs?
Does your dog seem sore in its hind end? Perhaps, he might have trouble getting up from lying down?
Many of the questions that I get asked online by owners worried about their pets are about how they can cope with their dog that has ‘sore hips’.
In the vast majority of these situations, we find that the problem is hip dysplasia. In this article, I will help you understand the following:
- what is hip dysplasia?
- how we prevent canine hip dysplasia?
- how we diagnose sore hips in the dog
- how we can treat our dog’s painful hips
Hip dysplasia in dogs is a condition caused by many factors influenced by the environmental and genetics that result in abnormal formation of the hip joint (ball and socket joint or coxofemoral joint).
There are many reasons why this disease syndrome occurs, some that we know about, and some that we have yet to identify. Hip dysplasia, therefore, is not one disease but many diseases that result in common arthritic (degenerative) lesions of the hip joint.
Problems with the pelvis and hips are common in large breed dogs, although any dog breed can be subject to hip issues and the resultant osteoarthritis.
Hip dysplasia is the most common inherited orthopaedic disease in dogs.
Although biomechanical and environmental factors associated with certain body conformation and size are considered as the main cause of canine hip dysplasia (CHD). CHD is a major welfare issue with many dogs suffering from pain and loss of mobility.
Heritability of CHD is around 25% (although for some breeds the range is 25-80%), meaning that the presence of CHD is only moderately caused by genetics and a lot more related to the environment. In saying that, studies in closed populations of German Shepherd dogs did show that breeding dogs that showed no radiographic signs of hip dysplasia at 1 year of age, resulted in a decrease in the incidence of hip dysplasia from 37.9% to less than 17% after 3.5 years of breeding.(1)
Most Common Breeds That Suffer From Hip Dysplasia
- German Shepherd
- American Staffordshire terriers,
- St. Bernards,
- Golden retrievers,
- Labrador retrievers
- Bernards labrador
- Alaskan Malamute
What Does A Normal Dog Hip Joint Look Like?
To be able to understand hip dysplasia we need to have a basic understanding of the hip joint.
The hip joint forms the attachment of the hind leg to the body and is called a ball and socket joint (coxofemoral joint).
The ball portion is the head of the femur (red) while the socket (acetabulum) (black) is located on the pelvis.
In a normal joint the ball rotates freely within the socket due to the bones being perfectly shaped to match each other.
The area where the bones actually touch each other is called the articular surface. In a normal, healthy joint the articular surface is perfectly smooth and cushioned with a layer of spongy cartilage.
The joint also contains a highly viscous fluid called synovial fluid that lubricates the articular surfaces. Synovial fluid contains a high amount of hyaluronic acid, giving it its viscous properties, that helps the joint glide.
In a dog with normal hips, all of these factors i.e. the articular surface, the conformation of the whole pelvis and legs and the joint fluid work together to ensure the joint functions smoothly.
What Is Hip Dysplasia In Dogs?
The huge majority of dogs are born with normal hips. It is very rare to find congenital abnormalities. It isn’t until dogs start growing up and exercising that we begin to see problems.
Canine Hip Dysplasia (CHD) is a condition that develops as dogs grow and exercise more. Rapid growth and inappropriate exercise can result in instability or laxity of the hip joint. The instability of the femur (ball) in the socket (acetabulum) results in a joint that rubs and grinds instead of sliding smoothly.
Over time degenerative joint changes occur such as acetabular bone sclerosis (hardening of the bone), osteophytosis (outgrowths of bone around the joint), thickened femoral neck, joint capsule fibrosis, and subluxation or luxation of the femoral head.
Three Main Risk Factors For Hip Dysplasia In Dogs
Hip dysplasia heritability is around 25% although it does differ between breeds.
To minimise the risk of a dog being prone to hip dysplasia, it is recommended to only select pups from breed lines where PennHIP scores are performed but the distraction factor is less than or very close to the average for that breed.
Research has shown that feeding a high calorie and high calcium diet predisposes a young pup to hip dysplasia.
Rapid weight gain and ad-lib feeding have been shown to result abnormal development of the hip joint.
Feeding a diet that has too much or too little calcium or other minerals can also have a detrimental effect on the development of bones and cartilage.
Fat, cuddly pups may look cute, but this predisposes them to developmental problems and you are doing them a long term disservice, resulting in a life of pain and discomfort.
Too much exercise at a young age, when bones are still developing can increase the risk of wear and tear to the hip joint.
Crucial times to restrict and be sensible with the type of exercise you give your dog is very early i.e. one month to six months of age.
During this age period, incorrect exercise can result in long-term damage to your pup’s hips.
When puppies exercise heavily, laxity between the femoral head and acetabulum is exacerbated and the joint is traumatized by the abnormal motion and impact of repeated subluxations and reductions. If the puppy is overweight then this trauma is further increased resulting in the joint having to cope with even more force.
It has been shown that keeping pups confined and cage rested until 9mths old decreases the risk of hip dysplasia.
But like anything, it is ridiculous to think we will lock up our dogs and treat with cotton wool.
Instead, it is a balancing act between giving a pup adequate exercise and socialisation and trying to prevent trauma to their musculoskeletal system.
Sensible restrictions are required.
Tests For Canine Hip Dysplasia
The PennHIP method of assessment for risk of hip dysplasia is the current gold standard.
The PennHIP method measures hip laxity using the distraction index DI.
The closer the DI number is to 0 the tighter the hips (less laxity and less chance of hip dysplasia). DI numbers close to 1 mean the hips have high laxity and it is highly likely the dog will succumb to hip dysplasia. Studies have shown that dogs with a DI score of less than 0.3 do not get hip dysplasia.
Puppies can have their hips assessed from as early as 16 weeks old, with no risk to them. This is a good idea if your pup is one of the “at risk” breeds as it allows you to plan appropriate exercise and feeding levels.
When choosing a dog it is always best to check the breed standard and choose from parents that have lower than breed average PennHip scores. The breed standard values can be found here: PennHip Breed Scores
You can learn more about the PennHIP method here.
Signs Of Hip Dysplasia
In some young dogs there may be no obvious lameness or muscle atrophy, while in others lameness and muscle atrophy is very noticeable. Those dogs with no lameness will often become lame with exercise.
Changes in gait can be subtle: walking with hind legs close together (base narrow), and decreased flexion through the stifle and hock so that weight shifts forward onto forelimbs. Some may bunny hop and as the disease progresses they have trouble rising, especially on smooth surfaces.
When a veterinarian checks movement of the hips, they will often appreciate a decrease in the ability to extend the hip. Flexion is usually normal, except in very severe cases with capsule fibrosis.
Muscle wastage is a sign that the condition has been going on for quite some time.
Radiographs are used to determine the degree of arthritis and for planning treatments.
How To Prevent Hip Dysplasia
1. Choose your pup wisely. If you are a breeder, breed wisely. Basically what we mean here is that you try to choose a pup whose parents have had PennHIP scores performed and the distraction score is ideally lower than or close to the breed standard.
2. Avoid running, jumping and slippery smooth surfaces especially for young dogs. In young pups, balance cage rest with exercise and avoid climbing stairs.
3. Feed a complete and balanced diet. Don’t feed adlib. Don’t add extra supplements without consulting a veterinary nutritionist. Be wary of feeding unbalanced raw diets.
How To Treat Hip Dysplasia
Treatment of hip dysplasia can be conservative, medical and/or surgical.
Conservative treatments involve weight management, restriction of exercise especially on hard and slick surfaces, physical therapy and swimming. Keeping the dog warm also provides great relief from pain caused by muscle spasm.
Medications involve using anti-inflammatories, injectable nutraceuticals and oral nutraceuticals. There are many joint supplements on the market and making a detailed list of these involving pros and cons is a topic for another day.
Surgery for some animals can be an option with better results seen when muscle wastage is not too noticeable.
In pups that have been diagnosed very young (3-4 months old) juvenile pubic symphysiodesis surgery is an option. This procedure uses electrocautery to kill the growth physis at the ventral midline, or pelvic symphysis. This stops growth in this area while other parts of the pelvis continue to grow resulting in a better alignment of the ball and socket hip joint.
In older animals the most common surgery is the femoral head and neck excision (FHNE). Basically, this removes the whole ball part of the hip joint so that no rubbing occurs. Dogs are encouraged to exercise soon after surgery, with results generally being very good. Result success decreases as weight increases and if muscle wastage is already prominent.
For those dogs that are up to one year old with very minimal radiographic signs of degeneration and nice deep sockets (acetabuli) triple pelvic osteotomy (T.P.O.) may be an option. This surgery prevents hip subluxation by rotating the dorsal rim of the acetabulum laterally to provide more coverage of the femoral head. This surgery has excellent results if performed before any sign of arthritis are seen on radiographs.
Big dogs who are in a lot of pain and have irreparable joint disease may be a candidate for total hip arthroplasty (THA). This is just like a hip replacement in humans. Careful case selection is required.
Summary Of Hip Dysplasia In Dogs
It is the most commonly inherited orthopaedic disease in dogs.
It is a degenerative, developmental condition, leading to painful hip osteoarthritis, stiffness, and diminished quality of life.
All dog breeds are affected by the disease, in some breeds more than 50% of dogs are afflicted.
The disease is polygenic and multifactorial.
The development of CHD is affected by environmental factors such as weight and age and nutrition.
There is no medical or surgical cure for CHD.
CHD is a major concern for working dogs, pet owners, breeders and veterinarians.
1. Riser WH, Shirer JF: Correlation between canine hip dysplasia and pelvic muscle mass: A study of 95 dogs. Am J Vet Res 124:769, 1967
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