Breed information HD - ED
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HD - ED genetically determined or not?
In veterinary world hip dysplasia (HD) and elbow dysplasia (ED) are the most common orthopedic disorders. Both occur mainly in medium and large dogs, both are developmental, and both are for the patient often a source of much pain and discomfort. In addition to that, despite the efforts of individual breeders and kennel clubs, HD and ED can unexpectedly appear in one or more dogs, while siblings of the same dogs show no clinical signs of lameness.
Is HD and ED genetically determined?
Influences of the environment on HD and ED Dr. Kealy conducted a very interesting study with 20 couples Labradors. [1] per couple 2 siblings of the same sex, were housed together in a kennel. One of the two could eat as much as they wanted, while the other 2 / 3 of that amount was. At regular intervals all dogs were weighed and X-rayed. The dogs were allowed unlimited food reached an average body weight of 32 kg, their littermates that the limited amount of food had reached an average weight of 23 kg, while all dogs had the same leg length. The laxity of the hips (expressed by the Norberg) and the degree of osteoarthrosis was the unlimited fed dogs larger than the restricted fed dogs. For Great Danes raised on food with many minerals, vitamins and energy Dr Hedhammar showed that unlimited fed dogs stayed behind in their developing of the head and neck compared with limited rear lined littermates, this caused that the head didn't fit well in the joints. [2] Dr. Kasström showed with litters of German Shepherds, Golden Retrievers and Labrador Retrievers that unrestricted diet led to more frequent and heavier HD then in restricted fed littermates. The ultimate hip score had more to do with nutrition and weight gain than with laxity of the joints in young dogs. [3] In the veterinarian clinic in Utrecht they demonstrated that in Great Danes raised on food with high calcium content, the cartilage cores in the elbow ossified in old age than was the case in dogs that grew up with a balanced feed with a lower calcium content. [4] also abnormalities in the length growth of the radius and ulna, which creates EI, were more frequently found in Great Danes that were too much calcium. You can frequently observe disturbances in cartilage transformation (OCD) in Danes who grew up with a calcium-rich food than siblings with a balanced diet. [5] For small dog breeds a high mineral diet food doesn't cause skeletal disorders that we see in the big races. [6] Even foods with high vitamin D levels can lead to symptoms of OCD and / or impaired growth of radius and ulna. Nap cs Research showed that a high protein food such as puppy food of good quality, has no negative effect on skeletal development. [7]
Summarized: rapidly growing dogs can develop HD and / or ED when they are raised on a vitamin or mineral-rich diet, or even if they are fed a balanced diet but in excessives amounts, while dogs of the same breed or even siblings of the same litter, who brought up with correct food and correct amounts do not get HD or ED. Dog food with the optimal amount of minerals, vitamins, proteins and carbohydrates creates the basis for normal cartilage development, ossification of the cartilage, and finally modeling of the bones. In earlier times, when there was no puppyfood available with a low mineral and energy, vets advised to feed puppies an adult dog food, so the absorption of minerals, vitamins and energy were and stayed limited. But because of the lower energy value of food the puppy was forced to eat more grams of that "adult" food. This caused that the daily intake of vitamins and minerals raised above the optimal amount, and skeletal disorders such as HD and ED were inadvertently encouraged. Recent research has shown that giant dog breeds that are raised on a balanced puppy diet with up to 0.8 to 1% calcium (% dry matter) shown a rappid process of bonerenewing known as a non-impaired cartilage growth and ossification of cartilage. In combination with a reduced energy intake (don't give to much) this creates the optimal conditions for an undisturbed skeletal development.
So HD and ED is not genetically dertermined?
We have seen that diet has a significant impact on the degree of ED and HD performance. This is especially true for young dogs of large breeds, which grow faster than small breed puppies. Studies of Nap cs among miniature poodles showed only a mild excess of minerals, clinically-relevant impact on the skeletal development in these small to medium dogs. Dr. Ubbink and others showed that the Dutch Labrador population is found in some ED related subpopulations. Also showed that LPC Ubbink and OCD mainly occur in different subpopulations, and only rarely are found simultaneously in the same subpopulation. [8] In a study of Bernese Mountain Dogs with radiographically diagnosed ED (especially with LPC EI) showed that these same dogs lifestyle, housing and feeding regimes had a similar group of Bernese Mountain Dogs with ED-free elbow joints on radiographs. These studies seem to indicate that the development of ED is independent of diet, lifestyle or housing. Population analysis indicated that HD and ED low heritability level (h ²) have, for various other varieties under more or less uniform environmental conditions ranging from 0.2 to 0.6 for HD, and from 0.24 to 0.55 for ED. [9] In other words, both HD and ED requires a strong influence of the environment to clearly reflected.
If we combine the results of these studies, it can be concluded that ED and HD occur in dogs of certain breeds and that these abnormalities will develop under certain environmental conditions. The influence of food - one of those circumstances - is fairly scarce. Theoretically it would be possible dogs vulnerable varieties to grow under environmental conditions that are reflected from HD and ED in order to facilitate the genotypic sufferers find. We will be more inclined to young dogs of HD-and ED-sensitive varieties to raise with optimum quality and quantity of food, and with limited movement, not the risk that we encourage the development of skeletal disorders. The result is that the genotypes of HD and ED undetected in the population, and only emerge in a generation, as descendants of phenotypically free dogs in poorer conditions are raised. To avoid the genes for HD and ED in the population dispersal, the breeding closely at HD and ED to be examined, with the most modern techniques. For breeding, dogs with unaffected joints or with the least serious degree of the disorder are used. Examination of whole litters of Labrador Retrievers showed that parents from phenotypically healthy dogs are born with ED. [10] Analysis revealed that the gene for LPC in this race probably dominant with variable expression is, especially in males corresponds to the genotype with the phenotype, while in females the gene may remain hidden for LPC. This mode of inheritance is half cause of unexpected re-action of a skeletal abnormality in one generation. Studies in dogs with HD have demonstrated that this is probably a polygenetic disorder, in which several different genes have come together to express the HD in an affected dog. [11] Environmental factor, that means many things. A good diet is the beginning. Will the dog regularly, play with other dogs, goes for long walks, go behind the ball. Slips now and again. Does he run up and down the stairs. Does he fall sometimes during his play. His body gets so much to endure. Is there a strong hereditary factor in your dog, then with all the daily enviroment factors and by wrong / poor nutrition you can have the bad luck that your dog will suffer from HD /ED. You compare that with a dog that is somewhere in the kennel, which is quieter and might not play with other dogs, and doesn't go for long walks than he makes it likely that the HD will result in this dog will better, because the owner is very careful. But remember from the outside you can not see how good or bad the hips of your dog are, sometimes you see nothing but the hips are super bad, because that is the way of walking a dog has developed which he himself but it can also be relieved that the dog was so muscled up relatively well so everything is in place. |