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Genetic diseas torment dogs

Satu Lehtinen

 

Some ten years ago, Finnish dogs received their own health programme, which not only indicates how mad Finns are about dogs, but also that there is a real need for such a programme. It is rather usual for pedigree dogs to suffer from genetic diseases or defects. Minna Leppänen, a specialist in small animal diseases, has written her doctoral dissertation on the use of health programmes for controlling canine genetic diseases in Finland.

In the Finnish Kennel Club’s control pro- gramme for canine genetic diseases (Pevisa), tens of thousands of dogs have been examined with regard to the health of their hip and elbow joints, and the prevalence of various genetic eye and liver diseases. More than a third of the examined dogs had hip dysplasia, while every fourth suffered from defects of the elbow joint.

According to Minna Leppänen, hip and elbow joint defects are particularly common in large dogs. “When the dog has to grow from a few hundred grams to as many as 80 kilos in a short period of time, his bones and joints are under a huge strain. In some breeds, a healthy dog is almost an exception; for example, as many as 70 per cent of Saint Bernard dogs suffer from hip dysplasia.”

Genetic hip defects are also common among the Finnish favourite breeds, German Shepherd and Golden Retriever. At their worst, hip and elbow defects result in severe arthrosis: the dog cannot move normally and is in constant pain. The severest eye diseases, on the other hand, make the dog blind rather rapidly.

From health programme to breeding index

Altogether 400 canine genetic diseases are known today, and only a fraction of these could be included in the Pevisa programme. Dogs are examined according to their breed; for example, in several breeds, at least the breeding dogs’ eyes and hips are examined. If there are problems, the puppies may not be registered. The health programme currently covers some 90 breeds.

The Pevisa programme has also been criticised. It has not been of great help in improving canine health. It has not, however, been completely ineffective: without the programme, the situation could be even worse. Leppänen is convinced that the programme has helped to reduce the prevalence of severe hip defects.

“Our information collection system is very functional, but the information is not effectively used in breeding. For example, a hip X-ray only gives information on the dog’s phenotype, but fails to tell everything about its background or genotype. This way even a dog that has been assessed to have healthy hips can pass on hip dysplasia.”

Male dogs that have succeeded in exhibitions and hunting tests have been freely used in breeding, sometimes uncritically. Fashion trends also have an impact on breeding. “Sometimes there’s one star male in an exhibition that everyone wants to mate with their bitches. It’s as if people were only seeing one feature, such as the dog’s appearance, and are blind to everything else.”

The numerically most common breeds have champion males that have been used to produce tens or even hundreds of litters. This narrows the genetic material of the breed, which then fosters genetic diseases and defects.

The Finnish Kennel Club is planning to use the Pevisa programme more effectively. If everything goes as planned, breeding choices can, in future, be based on a breeding value index of hip and elbow joints to be calculated for dogs. The index will be determined not only according to the dog’s own hip and elbow results but also its parents’, siblings’ and possible descendants’ results.

Skin problems and bad manners

Dogs’ skin problems have recently increased drastically. The reason for this is yet unknown. Simple and inexpensive examination methods do not exist. Leppänen thinks that in addition to genotype, changes in the environment and feeding habits have an impact on skin diseases. Another area difficult to study is the hereditariness of characteristics. There are no suitable testing methods. Researchers agree that characteristics such as aggressiveness and timidity are hereditary. How big an impact environmental factors have, is still in dispute.

“A dog with an aggressive inclination can be a very good dog in the hands of a suitable owner. Yet people too easily say that the owner of a problem dog should just have a look in the mirror. I don’t fully agree. There can also be something the matter with the dog’s head.”

The idea that mongrels would be healthier than pedigree dogs is just a myth, according to Leppänen. The myth lives on partly because mongrels’ diseases are not registered.

“If you mate a German Shepherd suffering from hip dysplasia and genetic pancreatic insufficiency with a Dobermann that has a genetic liver defect, how could the puppies be healthier than pedigrees?”

The happy dog’s life

A genetic disease or defect does not necessarily doom the dog to misery. Some eye diseases have no impact whatsoever on the dog’s life. Bad hips do not automatically mean that the dog’s quality of life is worse. Leppänen points out that we have many dogs that lead happy lives in spite of defects or diseases.

“Dogs are individuals. Nobody can predict whether a dog will still be in top form after ten years or crippled with arthrosis.”

Besides genotype, environmental factors such as food and exercise also have an impact on the condition of hips. All active factors are not yet even known. According to Leppänen’s research, one factor could be the month of birth of the puppy. German Shepherd puppies born between February and July had healthier hips when adults than others. One explanation for this could be that puppies born in spring and summer get more exercise outdoors than puppies born in the cold of autumn and winter.

In addition to her research work, Leppänen has been working as a vet for a good ten years. There is plenty of work, since the five million Finns have altogether over half a million dogs.

“Finnish dogs are usually very well cared for. Even working dogs are family members,” Leppänen says. This is also true in her own family: when her daughter talks about her baby brother, she is referring to their Pinscher.