Introduction
Hip dysplasia is a hereditary disease that, in its more severe form, can eventually cause crippling lameness and painful arthritis of the joints. It is caused by a combination of genetic and environmental factors.
Hip dysplasia is the most common single cause of arthritis of the hips.
Normal Hips vs. Dysplastic Hips
In the normal anatomy of the hip joint, the femur (thigh bone) is connected to the pelvis at the hip joint. While bones provide the strength necessary to support body weight, cartilage ensures a smooth fit and a wide range of motion.
In hips suffering from dysplasia there are two primary abnormalities. First, instead of a deep tight fit, the femur fits into the pelvis loosely or partially. Secondly, abnormalities in the shapes of the bones cause wear and tear within the joint as it moves.
Causes of Hip Dysplasia
There is considerable evidence that genetics plays a large role in the development of this defect. Several genetic factors can contribute to the problem including a femur that does not fit correctly into the pelvic socket, or poorly developed muscles in the pelvic area. Symptoms almost always appears by 18 months of age and the defect can range anywhere from mild to severely crippling.
Symptoms of Hip Dysplasia
Common symptoms of hip dysplasia include:
- Stiffness or soreness after rising from rest
- Reluctance to exercise
- Bunny-hopping or other abnormal gait
- Lameness
- Reluctance to stand on rear legs, jump up, or climb stairs
- Subluxation or dislocation of the hip joint
- Wasting away of the muscle mass in the hip area
Diagnosing Hip Dysplasia
X-rays can confirm hip dysplasia, but many radiographic indications may not be evident until two years of age in some cats.
The most common diagnostic techniques are x-rays and hip scoring tests. Since the condition is largely inherited, hip scores of parents should be professionally checked before purchasing a pet.
Additionally, standardized systems for categorizing dysplasia have been established by several quality institutions including the Orthopedic Foundation for Animals (OFA), PennHIP, and British Veterinary Association (BVA).