Hip Dysplasia in Pets

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The most common symptom of this genetic disease is limping, but dogs with hip dysplasia might also walk funny, have a hard time jumping or rising, or lose muscle bulk in their thighs. Pain-relieving drugs, joint supplements, and maintaining a proper weight help manage the condition, which causes crippling arthritis, but, unfortunately, a true solution for many can come only through surgery.

Overview

In the world of small animal veterinary medicine, hip dysplasia is considered the mother of all orthopedic diseases for being so common, so crippling, and yet so frustratingly insidious. It’s very common in large dogs, relatively common in smaller dogs, and even seen in cats.

Hip dysplasia is painful and can be expensive to treat. It’s also preventable. But this last point is a complex matter — especially when you consider that hip dysplasia is acquired primarily through hereditary means.

This genetically predetermined disease that causes mild to severe changes to the inner workings of the hip joint happens when an animal (usually a large breed dog) inherits a series of genes specific to how this joint’s components (made up of the bones of the femur and pelvis) fit together. More specifically, it has to do with how the femoral head (the ball portion of the femur) and acetabulum (the pelvis’s hip socket) align to achieve the kind of smooth movement a pet requires for a lifetime of weight bearing and normal wear and tear. One or both hips may be involved.

Signs and Identification

The problem with hip dysplasia is that it’s not always obvious that your pet has it. Because its severity is variable due to the way this disease is inherited, some pets will show signs as early as 4 months old, while others surprise us with symptoms that appear only when they reach middle age or even later.

If untreated, arthritis (often referred to as osteoarthritis) is the result in all cases. Because the bones of the joint don’t line up just right, the joint cartilage is subjected to abnormal wear and tear. Over time, cartilage damage occurs, resulting in pain and arthritis.

Limping is the most apparent sign but, as if to confuse us further, is not always present. Loss of muscle mass in one or both thighs, reluctance to jump, a funny way of walking, or slowness in rising can also signal the presence of this hip disease.

A diagnosis of hip dysplasia is made based on clinical signs, physical examination, and radiographs (x-rays). Two systems have also been developed for screening and/or diagnosing dogs with hip dysplasia. Responsible breeders use at least one of these systems before including a dog in their breeding program:

  • The OFA System: The Orthopedic Foundation for Animals (OFA) oversees a multibreed hip registry database. The OFA’s system, which has been in use since 1966, has developed a standardized evaluation system and radiographic test to help breeders and owners assess the hip health of prospective parents as well as any puppies they may produce. Dogs must be 24 months of age or older to be included in the registry.
  • The PennHIP System: The PennHIP system, which was developed at the University of Pennsylvania School of Veterinary Medicine, has been in use since 1993. It uses a series of three radiographs to assess a “distraction index” — or DI — for each dog. The greater the DI, the higher the chances that the dog has or will develop hip dysplasia. The PennHIP analysis can be performed in puppies as young as 4 months of age.

Affected Breeds

Giant, large, and dwarfed, smaller breed dogs are most often affected, but mixed breed dogs and cats are not immune. According to the OFA, Bulldogs have a high prevalence of hip dysplasia with 72.6 percent of Bulldogs studied being affected. Of the Pugs studied, 64.3 percent were affected.

Several studies in veterinary journals have highlighted how common hip dysplasia is across different dog breeds. The OFA’s website also provides a full ranking of dog breeds and the percentage of the group that suffers from hip dysplasia according to OFA statistics. However, a study published in the Journal of the American Veterinary Medical Association in 2005 suggests that OFA statistics may underrepresent other affected breeds such as Rottweilers and Golden Retrievers.

Many owners are in denial about their pets’ hip status, especially when pain is not yet obvious to them. That’s because dogs don’t always display pain the same way humans do. Whining and complaining is just not in their nature. But veterinarians will know it’s there even before limping and other more obvious signs are present.

By 2 years of age, 95 percent of animals that have genes for hip dysplasia will show evidence on X-rays. But the severity of the dysplasia as seen on a normal X-ray doesn’t always indicate the degree of pain or lameness (limping). It also doesn’t tell us when a pet will begin to show signs of the disease.

Treatment

A proper diet that helps maintain an ideal weight, combined with a veterinarian-approved, regular exercise plan, can help slow the progression of hip dysplasia for some dogs. In less severe cases, medical management can also include providing pain medications as needed under veterinary supervision as well as administering oral or injectable joint supplements or medications. “Comfort care,” such as keeping dogs out of cold weather and performing massage or physical therapy, can also help keep affected dogs comfortable and slow progression of the disease for as long as possible.

In severe cases, surgery may be indicated. Surgical options include hip replacement surgery, reconstructing the hip joint, or removing the abnormal part of the joint and allowing the surrounding structures to form a “false joint” over time. Your veterinarian will discuss the best methods of management with you and whether surgery is an option for your dog.

Prevention

The onus for prevention is primarily on the breeders of dogs. If you intend to purchase or adopt dogs of a breed potentially affected by hip dysplasia, OFA or PennHIP certification of the parents’ acceptable hip quality is recommended.

This article has been reviewed by a Veterinarian.

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