By Jonathan Amos
BBC News Online science staff
The biggest survey into the health of purebred dogs in the UK has started.
Labrador breeders use a hip scoring scheme
More than 70,000 dog owners attached to 180 breed clubs are being asked to return information on disease, cause of death, birth defects, and other data.
The Kennel Club-backed survey will give the best picture yet of the frequency of breed-specific illnesses, such as the deafness seen in some Dalmatians.
It is hoped the data can then be used to develop new testing and breeding programmes to eliminate the conditions.
"Much of the information we have now is largely anecdotal," said Dr Jeff Sampson, the Kennel Club's canine genetics co-ordinator.
"The intention of the survey is to get - for the very first time - a real feel for the diseases that are out there and how frequently they occur.
"Breeders could then consider this information when selecting mates to put together and we would have a baseline against which we can measure improvements that might result from future health control schemes."
Dogs are plagued by the greatest number of documented, naturally occurring genetic disorders of any non-human species. And many of these conditions seem to crop up time and time again in specific breeds.
Lymphomas are reported in pointers; heart disease is seen in boxers; Dobermans can experience bleeding disorders; Labradors can have skeletal malformation in the hips; eyesight problems can afflict Irish setters.
The survey will ask specifically about the occurrence of cancer
But much of the existing data on the prevalence of these diseases is found, by and large, in reports from specialist veterinary referral hospitals or even in the documents of pet insurance claims.
It is, therefore, only a partial picture of sickness, not a comprehensive guide to dog health in the total population.
The new survey will give a more representative idea of what is happening in the wider dog population, and then quick-start a drive to better purebred health.
"We will work with breeders to find ways of having their breeding stock pre-screened," said Dr Sampson.
"This is already done with hip scores for Labradors, but we need to see more of this - and we'd like to develop more specific DNA tests for inherited disorders. There are about 50 already and more are coming."
Cause and effect
The survey has been designed by epidemiologists at the Animal Health Trust in Newmarket. The forms should be being circulated among owners of purebred dogs about now.
DOG DNA - CANIS FAMILIARIS
The double-stranded DNA molecule is held together by chemical components called bases
Adenine (A) bonds with thymine (T); cytosine(C) bonds with guanine (G)
These letters form the "code of life"; there are estimated to be about 2.4 billion base pairs in the dog genome wound into 40 distinct bundles, or chromosomes
Written in the DNA are possibly 30,000 genes which dog cells use to template the production of proteins; these sophisticated molecules build and maintain the animal's body
The Trust's Dr Vicki Adams says that as well as providing baseline data on the frequency of occurrence of health problems, the results may highlight a specific problem in one breed that had not previously been recognised and that may have an inherited component.
Further research will be needed in order to study the causes of any particular disease.
"While some health problems in purebred dogs have been shown to be due to specific genetic mutations, other health problems are thought to result from the selection of animals for breeding according to breed standards," she said.
"But the association of cause and effect is not always easy or obvious. This survey may also show that in some breeds there are no specific serious health problems."
The results should be available by the autumn. One group of scientists likely to have an interest in the outcome are researchers studying human genetics and disease.
Through the comparison of our biochemical code with the soon-to-be-finished dog genome, these scientists will hope to identify the particular gene errors that give rise to disease - in both humans and dogs.
Give and take
Many of the 400 or so inherited disorders reported in canines are also seen in humans.
It is also the case that dog versions of these diseases, particularly the cancers, look more like their human counterparts than some of the induced tumours scientists study in lab rodents.
Pedigree dogs are highly defined groups. They are just like isolated human populations - a closed gene pool - and for some canines there is family tree data at the Kennel Club going back more than a hundred years.
A breed standard calls for the dog to have a particular look
All of this means there are real spin-offs in dog research for the understanding of human health and behaviour.
Robert Kelly from the American Kennel Club's Canine Health Foundation is in no doubt the UK survey will provide an invaluable resource.
"We can breed out problems in dogs. The relatively short lifespan of dogs means you can do this quite quickly," he said.
"The most remarkable success I often quote is in progressive retinal atrophy in Irish setters. I haven't seen a case for many years - all because of a breeding programme that came out of genetics work that started at Cornell University."
He added: "And increasingly you will see human treatments benefiting dogs and dog treatments benefiting humans."