Large or giant breeds are the ones that most often come to mind when talking about Hip Dysplasia in dogs. Unfortunately, this problem has become more common in smaller breeds as well.
What is Hip Dysplasia?
The hip joint has a ball (top part of the femur) which fits into a joint (hip socket in the pelvis). If the hip socket is not developed properly the ball does not sit in it properly. This causes stress on the cartilage lining the hip joint. With the constant stress on the joint the cartilage thins and becomes stiffer which decreases the joint's ability to handle the daily stress of movement and weight bearing. Over time arthritis will build up in the joint and cause thickening and a decrease in range of motion along with accompanying pain.
This is a congenital, degenerative condition. It is a polygenic disease which means there are several genes operating to produce the condition as well as environmental factors involved such as rate of growth, nutrition (eg high protein, excess calcium), excess weight and too much or too little exercise. Certain breeds, primarily larger breeds such as German Shepherds, Golden Retrievers and Labrador Retrievers have a breed predisposition for this condition though it can occur in all dogs, even in a smaller dog as the Cavalier King Charles Spaniel.
Diagnosis and Implications for Breeding
Diagnosis of hip dysplasia is made by x-ray. As this is a degenerative disease, breeding stock in dogs with a breed disposition are x-rayed after the age of 2 for signs of the disease. An affected dog should not be used for breeding. In the Cavalier it had been a breeder's choice to x ray for hip dysplasia as the incidences of the condition had been fairly low. The increase in popularity of the breed, has resulted in a greater number of Cavaliers being bred, which in turn has resulted in the increase of documented cases of hip dysplasia. As with many other inherited diseases while x-raying may indicate that the individual does not have signs of hip dysplasis it does not answer the question of whether a dog is a carrier and can pass the condition to its offspring.
Treatment of Hip Dysplasia
Depending upon the severity of the condition treatment varies from the use of nutraceuticals such as glucosamine, Cosequin, shark cartilage, NSAIDS such as Rimadyl or Metacam, buffered Asprin or Bufferin, to surgery. It is also helpful in controlling the symptoms of HD to keep the dog's weight down as the excess weight puts more strain on the hips.
Toy breeds are very prone to lateral luxating patellas.
Patellar luxation has been common in Poodles, Yorkshire Terriers, Pomeranians, Pekingese, Chihuahuas, Miniature Pinschers and Boston Terriers over the past few years we are seeing a greater number of Cavalier Spaniels with this disorder. Females have the highest risk for this condition.
Diagnosis is relatively simple for a veterinarian familiar with orthopedics. It involves palpation of the joint and manual luxation of the patella. Care must be exercised with the examination to avoid injuring the joint, or making an incorrect diagnosis. Patellar luxation may be classified in four grades, with grade I being the mildest. This grading system is subjective so it is important in the present of luxation to have the same veterinarian perform the follow-up screening. Mild patellar luxation (grade 1-2) may be discovered as an incidental finding especially in a growing dog or a female in season. In addition, patellar luxation may occur in any breed because of trauma.
Patella luxation (also called slipped stifles) results from abnormalities in the bones of the rear legs, such as a shallow trochlear groove. This condition is easily checked by manipulation by a veterinarian. Patella luxation is graded into 4 degrees of severity.
The four degrees are:
Grade 1 - the stifle joint is almost normal and luxation is found on examination. Usually there is no gait abnormality.
Grade 2 - the patella lies loosely in its normal position but will luxate when the joint is flexed. Dogs with a Grade 2 may have a "bunny hop" gait where the patella moves out of the trochlear groove and the dog hops along on the good leg trying to kick the bad leg straight to move the patella back in place.
Grade 3 - the patella is dislocated much of the time but can be manipulated back into the joint when the leg is extended.
Grade 4 - the patella is dislocated all of the time and needs surgery to correct.
In both Grade 3 and 4 the dog shows varying degrees of lameness, often with a bowlegged appearance with the toes pointed in due to the deformity of the rear legs.
Pain is usually not associated with this condition unless it is the result of trauma or until degenerative arthritis has occurred due to chronicity of disease.
The treatment and long-term outcome (prognosis) depend on the severity of disease. Severity is determined how often the kneecap slips out of place, and how easily it slips back into the normal position. Treatment is based upon severity of signs and the affected Cavalier’s age, breed and weight. Conservative therapy (non-surgical) and veterinary observation is often the treatment of choice. However, if the patellar luxation has persistent lameness, or other knee injuries occur secondary to the luxation, then surgery intervention needs to be evaluated.
Cavaliers used for breeding should have within normal limits patellas as determined by an OFA examination at age one. The patellas should be reevaluated as the Cavalier’s ages.
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