Inheritance of dysplasia (HD)
In most dogs, disorders are not clinically apparent, but it cannot be considered that apparently healthy dogs are free of dysplasia. Joint pain is manifested only with a severe form of the disease. It should be borne in mind that this pathology can be transmitted through 14 generations. Many countries have anti-HD programs. The main difficulties arise in the diagnosis, a clear definition of the degree of the disease. The only effective measure to combat hip dysplasia in dogs is the rejection of identified sick animals from breeding.
According to various sources, HD heritability ranges from 60 to 20%, but the most extensive studies indicate that it averages 25-35%. When mating defective parents, the probability of getting sick offspring increases by 2 times.
It does not make sense to immediately harshly exclude all sick dogs from breeding – you also cannot make dysplasia a determining factor in breeding, forgetting about the exterior, working qualities and temperament. Dogs with a mild degree of dysplasia, especially outstanding in other qualities, should not be abandoned. Practice has shown that even with the gradual exclusion of dogs with HD from breeding, great success can be achieved. We must not forget that, even if the dog has successfully passed the x-ray, and it is free from dysplasia, it can still give offspring that are unsuccessful in this respect. But the survey results show that the healthier the parents and relatives of the crossed dogs in HD, the higher their percentage of HD-free puppies. When parents were free of dysplasia (selection in two generations), the percentage of healthy puppies reached 76%.
What every dog expert, expert, breeder, owner and person who wants to buy a dog should know. Clinical signs and prevention.
Fortunately for owners, only 20% of dogs with diseased joints have obvious clinical manifestations. The slightest deviations do not lead to tangible clinical manifestations in the dog, and, as a rule, remain invisible to its owner. Symptoms are absent or so weak that they do not affect the well-being and working use of the dog.
The first signs of the disease can usually be observed in dogs older than 5-6 months. In mild cases, the puppy or young dog has a slight weakness of the hind limbs, at times a slight limp on one or both limbs with prolonged movement or increased load. When the dog sits down, it wraps its hip inward, pulling it closer to the stomach. When activating a litter, a dog handler is recommended to inspect each puppy in motion. Late-walking puppies, puppies with hind limbs spreading out on a non-slip surface and not holding a stance should alert. At the same time, puppies with small deviations can be left until a second examination after 2 weeks, but even with full normalization of movements, they are the first in the risk group. At the same time, it was noticed that puppies who, at the age of 30 days or more (and some adults), take a “chicken chicken” pose with limbs extended and stretched back during rest and feel quite comfortable in it and easily jump out of it, have further radiologically healthy joints. However, this provision still needs final confirmation by statistical material. In older (2-6 months) puppies, the weakness of the backside after small runs (the puppy tends to sit or lie down, often overloading the backside), poor coordination and avoidance of movements associated with a large load on the joint (jumping up in place, a sharp change) should alert directions for the entire race, etc.).
When studying German Shepherd puppies, a direct relationship was found between the development of HD and the rate of weight gain – sick puppies weighed a little more. These data were confirmed on Labrador Retriever. The conclusion follows: at an early age, when the bones still contain a lot of cartilage (up to 5-6 months), a rapid increase in weight contributes to the development of bone abnormalities. It is possible to “spoil” the correct joints, but it is not possible to avoid HD development in puppies with “bad heredity” by any means.
From these positions, the puppy of the best when producing litter “presentation” immediately falls into the risk group for HD. This is worth considering for those clubs where the elephant weight of puppies, even if they are barely moving, is considered the main criterion for an excellent litter score. Undoubtedly, overweight puppy significantly increases the load on the hip joints. At the same time, the nature of nutrition plays an important role: protein food helps to build muscle mass, balanced mineral nutrition, vitamins and trace elements affect the rate of growth and development of body tissues, the development and ossification of the skeleton. A lack or excess of minerals, trace elements and vitamins can also lead to irreversible changes in the hip joints.