So long! Helka’s litter
Aug 08, 2012 – 11:17 AM | No Comment

We are proud to announce the birth of three little miracles (Galga, Gercse and Gemenc) on August 31 by Chankazz Helka and Galla-Hegyi Nótás! Read more on the page for our G litter!

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Home » Pumi health

Canine hip dysplasia and breeding

Submitted by on Apr 07, 2010 – 3:16 PMNo Comment
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In the third part of our series we will consider the relationship between hip dysplasia and breeding. While environmental effects, to include nutrition and exercise, may play a part in mitigating or delaying the onset of clinical signs and clinical symptoms, hip dysplasia remains a genetically transmitted disease.

The importance of hip dysplasia awareness and rigorous genetic selection in breeding can easily be understood by a counter example: human hip dysplasia is a spreading disease in the civilised world due to the fact that with modern scientific methods for early diagnosis and treatment more and more affected people can lead normal adult lives free of any symptoms. By the time they decide to settle down and found a family, they probably have all forgotten about their disease and it never occurs to them that they might be transmitting their faulty genes, and a potentially crippling disease, to the next generation. In fact, hereditary hip dysplasia is the most common orthopaedic abnormality in humans today, affecting 0.5-2% of all children born. (NOTE: hip dysplasia in humans already forms in the womb as opposed to canine hip dysplasia, which develops in young and adolescent dogs.) Trans-generation studies have shown that if one parent is affected, there is a chance of 1 to 10 that the offspring will also develop hip dysplasia.

In dog breeding, however, the incidence rate could and should be reduced by careful selection, even though some articles in favour of other methods or no screening at all claim that the breeding programs aimed at eliminating hip dysplasia have failed because there are affected puppies born after HD-free parents. Surely enough, the incidence of hip dysplasia in any breed has not declined as rapidly as had been hoped when such schemes were put into operation. This is due to the fact that unfortunately dogs with good hip scores can still carry the genes responsible for the condition, so two good parents will not guarantee problem-free offspring. However, this does not mean that the system doesn’t work. Changing around the genetic pool of a breed is not a question of decades, but of centuries.

There is no other method of preventing hip dysplasia except for a thoughtful and carefully executed breeding program with regular radiographic analysis of all stock before breeding. The ancestors of our dogs, of course, underwent tests of a different kind – death, often painful, came to dogs whose constitutions did not allow them to withstand many kilometers of running, long periods of exposure to the elements, periods of starvation, etc. But here in the twentieth century, we don’t have this level of natural selection operating. Most puppies do grow up and some are affected by genetic defects, much to the heartbreak of their owners. By breeding only those dogs certified as free of dysplasia, the efforts to eliminate the disease are continued.

If you are not x-raying your breeding animals or if you are publishing falsified data about your dogs and kennel by manipulating or withholding results, then you may contribute to the problem rather than the solution. It is possible to reduce symptoms entirely to the point where the dog will radiograph much less severely by joint supplements and a strict diet, however, follow-up studies show that these dog’s offspring have the same risk for hip dysplasia as they would have whether the parents had been so treated. The implication is that it is unethical to use as breeding stock dogs that were treated to prevent their symptoms from disappearing. (On the other hand, pet owners with no intention of breeding their dogs might consider this option.) Also, from an ethical, and even from legal point of view (depending on the terms of your puppy sales contract), you can be held responsible for deliberate deceit and ethical misconduct at any court of law.

Inbreeding is often thought to be the cause of all troubles, even though inbreeding dogs can actually decrease the incidence of dysplasia in a line. The more inbreeding, the lower the heritability index because inbreeding reduces the total genetic variability, that is, the gene pool is smaller. Inbreeding is not really a bad thing, in fact all purebred dogs are inbred to some extent. Inbreeding only becomes problematic when undesirable genetic traits are concentrated within the gene pool. The appearance of some highly praised breed-specific characteristics is as much due to high
selection intensities in genetically closed dog populations as the accumulation of breed-specific disorders. Another likely reason for the high frequency of disorders is the founder effect.

Most dog breeds, including the pumi, have been established from only a few founder animals, and a uniform appearance of dogs within breeds was achieved by intense inbreeding. Since establishing the uniform breed type, inbreeding has continued to be used by many dog breeders, often taking it much too far.

Sure, small, closed populations make inbreeding to some extent inevitable, but the common practice of excessively favouring only a few sires and lines in breeding causes effective population sizes of many dog breeds to be further smaller. The “popular sire syndrome” has raised the average relationship between the animals within the Hungarian pumi population as well. Together, the founder effect, the high selection intensities, and the extensive use of popular sires have possibly made the within-breed allele diversity limited, and thus influenced the accumulation of genetic defects in the modern purebred dog breeds. In the future, excessive inbreeding should be avoided in these breeds by using a larger proportion of the animals, especially males, for breeding, and by keeping progeny group sizes as uniform as possible between the animals.

The joy of breeding dogs does not lie in constant fear of defects. The joy lies in producing positive traits, dogs of outstanding type, gait and temperament who are a joy to look at and live with. After all, most puppy buyers want to have a sound dog with a good character. We believe that it is possible to decrease the incidence of genetic defects while still preserving type. Preserving type is, after all, the only reason one should be breeding.

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