Inherited Bone Conditions
If after careful veterinary examination and xrays, one of these conditions is found, it is recommended by veterinary surgeons that animals should not be used for breeding purposes.
Canine Hip Dysplasia
This is the most common cause of rear-end lameness in the dog. It occurs almost exclusively in the larger breeds – those weighing more than 35 pounds as adults.
The problem lies in the structure of the hip joint. The head of the femur (thigh bone) should sit solidly in the acetabulum (Cup). In hip dysplasia loose ligaments allow the head to begin to work free. A shallow acetabulum also predisposes to joint laxity. Finally, the mass or tone of the muscles around the joint socket is an important factor.
Tight ligaments, broad pelvis with a well-cupped acetabulum, and a good ration of muscle mass to size of bone, predispose to good hips. The reverse is true of dogs who are likely to develop the disease. Environmental factors, including weight and nutrition of the puppy and rearing practices figure into the final outcome.
Hip dysplasia is an heritable condition. It is about twice as common among littermates having dysplastic parent. But even dogs with normal hips can produce dysplastic pups. Some dogs with x-ray evidence of severe hip dysplasia show no clinical signs and the disease goes entirely unsuspected until an x-ray is taken to check for it.
Signs first appear during a time of rapid growth (four to nine months). A puppy might show pain in the hip, walk with a limp or swaying gait, bunny hop when he runs, and experience difficulty getting up. Pushing down on the rump often causes his pelvis to drop. If you roll him on his back, his rear legs may resist being spread into a frog-leg position.
Canine hip dysplasia is graded under the KC. Hip Dysplasia scheme from the age of 12 months. This should always be undertaken prior to breeding your animals.
There are two surgical procedures advocated in the treatment of hip dysplasia 1. Removal of the femoral head (s) and 2. Division of the pectineus muscle. These procedures may relieve pain and improve function in some individuals.
It has been shown that repeated selection of normal dogs for breeding stock reduces the incidence of hip dysplasia in a susceptible bloodline.
Elbow Dysplasia (Ununited Anconeal Process)
The condition is caused by a faulty union of the anconeal process (one of the elbow bones) with ulna. It is of developmental origin. Again it is thought to be inherited.
The loose fragment in the elbow acts as an irritant and abrasive arthritis is a common sequel.
Pups begin to show lameness in the front leg at about six months of age. Some are unable to bear weight; others limp only when trotting. Characteristically, the elbow is held outward from the chest. Again the most effective treatment is surgical removal of the loose pieces of bone.
Slipping Kneecap (Patellar Dislocation)
Dislocating kneecap can be inherited, or acquired through trauma. It occurs sporadically among Toy breed dogs, although of late has been found in larger breed as well.
In dogs the kneecap is a small bone which protects the front of the stifle joint: it is the counterpart of the kneecap in man. It is anchored in place by ligaments, and slides in a groove in the femur.
Conditions which predispose to dislocation of the patella are: a shallow groove; weak ligaments; and mal-alignment of the tendons and muscles that straighten the joint. The patella slips inward or outward.
The signs of a slipped kneecap are difficulty straightening the knee; pain in the stifle; and a limp. The ti of the hock often points outward and the toes inward (the reverse of cow hocks).
The diagnosis is confirmed by manipulating the stifle joint and pushing the kneecap in and out of position.
The treatment to repair involves surgery to deepen the groove and/or realign the tendon.
Popping Hock (Laxity of the Hock Joint)
This condition, which may affect one or both hocks, is due to looseness of supporting structures around the joint. It is more common in large dogs with straight rear-end angulations. Usually it is not painful, but can impair the dog’s drive and agility. In late stages the joint can become arthritic.
The diagnosis can be suspected by observing the dog in motion, at which time the hock will appear to give, causing an irregular gait. Manipulation of the joint reveals the lax ligaments. The hock slips out of place (either forward or to the side) when the joint is straightened.
Treatment: Early immobilization by splints (or cage rest) may reversed the condition in some young pups. The disease is carried in certain bloodlines. It can be reduced by proper breeding practices.
Separation of Joint Cartilage (Osteochondritis dissecans)
Osteochondritis dissecans affects dogs of the large rapidly growing breeds between the ages of four and twelve months. It usually is found in the shoulder joints, but rarely it can affect the hocks or stifles.
It is due to a defects in the cartilage overlying the head of one of the long bones. A puppy who jumps down stairs might sustain such an injury. The tendency for cartilage to be easily damaged may be hereditary. Repeated stress to the joint perpetrates the condition.
The signs are gradual lameness in a young dog of one of the larger breeds. Pain is present on flexing the joint. X-rays may show fragmentation of the joint cartilage, or a loose piece of cartilage in the joint.
Treatment: The condition can be treated by confinement, or by surgical removal of the damaged cartilage. Pain tablets are contraindicated, as they are in most traumatic joint conditions, because they encourage the dog to exercise.