Among the 5,000 or so species of mammals in the world, how many of them can show a forty-fold difference in size between two fully grown adults?
The answer, as any dog owner will probably know already, is just one. Their pet is a member of a unique species whose bodily shape has been moulded into a greater variety of distinct forms than other creature on Earth. Indeed, it is sometimes hard to believe that a tiny Chihuahua and a massive Great Dane are cut from the same genetic cloth.
Renowned canine geneticist Elaine Ostrander has done more than anyone to unravel the threads that link the different dog breeds and show which genes determine both their physical appearance and their susceptibility to inherited diseases.
Professor Ostrander, head of the comparative genetics section of the US National Human Genome Research Institute, was the leader of the international research team that drew up the first map of the canine genome in 2004. For that, she won the lifetime achievement award in the inaugural Kennel Club International Canine Health Awards in 2013, which were supported by American couple Vernon and Shirley Hill of Metro Bank.
She says she is extremely thankful to the Kennel Club for the certificate, which holds pride of place on the wall of her office in Bethesda, Maryland and for the £10,000 in prize money, which has helped her to continue her work. But she is even more grateful for the routine work that the Club has been doing for the past 143 years in regulating the world of pedigree dogs and recording the results of matings within each of the 209 different breeds recognised in the UK.
“The Club and its sister organisations around the world are responsible for the integrity of the pedigree breeds. That is why the Kennel Club award is so important for me,” she says.
“The work that we have been doing would have been considerably more difficult, maybe even impossible, if we had been looking at an outbred population like that of non-pedigree dogs – or our own species. The KC’s rules on record keeping are strict and as far as we are concerned, the stricter the better, as that means that the information we are collecting is much more reliable.”
Elaine trained as a molecular biologist and began her research career at the University of Washington where she studied the structure of DNA in humans and the commonly used laboratory animal species, such as mice and rats. But when the Human Genome Project was launched in the 1990s and successfully produced the first detailed map of human DNA in 2001, she knew which species she wanted to work on.
“In dogs, the activity of their genes creates a huge variety of what we term phenotypic effects such as body size, head shape, leg length and coat type. At the laboratory where I was working, the Frank Hutchinson Cancer Research Center in Seattle, we were interested in the factors that regulate the growth of tumours. So being able to use these maps to navigate your way around the genome to find the specific genes involved in creating particular physical traits was a really cool thing to do.”
Her research has involved taking tissue samples from members of particular breeds and analysing the DNA to find the genes responsible for a number of conditions such as epilepsy, the eye disease retinitis pigmentosum and tumours affecting a variety of different body systems.
“The traits we are looking for are so much more obvious visually and biologically in a dog than they would be in, say, a rodent. And what is exciting is that they often correlate closely with what we see in humans. So the mechanisms that cause the huge range of body sizes in dogs are essentially much the same as the factors responsible for the differences between my mother-in-law who is just five feet tall and one of the guys in our lab who has reached a height of six feet six inches.”
When the first genetic studies were published they created a generalised map intended to represent the whole canine species. Since then the technology involved has become highly automated and considerably cheaper and so it is now possible to sequence the DNA of individual breeds. As a result, the underlying science is progressing rapidly and helping to establish the genetic causes of increasing numbers of diseases. This is reflected in a huge growth in the numbers of genetic tests that are available to dog breeders to assist them in producing healthier puppies.
Canine geneticists from all around the world meet up every other
year to discuss their latest findings and plot the course of future studies. The next meeting is to be in Minnesota in May 2017 and will be attended by officials from the US Kennel Club. Elaine hopes that representatives of other national kennel clubs will also be there, as the funding available to improve canine health is limited and better international coordination of this research is needed to ensure that that money is well spent, she says.
There is another reason why Elaine advocates closer collaboration between all those involved in funding or carrying out research into canine inherited disease. Complete genetic sequences have now been completed for at least 500 different dogs of various different pedigree breeds and various crossbreeds. These have shown that the evolutionary process started by dog owners when they began selective breeding is still going on.
Research has shown that while the populations of dogs in some breeds are much the same on both sides of the Atlantic, others have begun to diverge. Elaine points out that it will be important to understand the reasons why some pedigree lines are changing and others are not – and to assess the implications for the future health of those breeds.
Since the completion of the canine gene map, Elaine’s employer, the US National Institutes of Health has continued to support research into canine genetics. But that is more to do with its potential value in understanding human disease than a concern with improving canine health.
However, the potential benefits of comparative studies in humans and dogs can go both ways. Many of the diseases shared between the two species are a result of interactions between genetic and environmental factors. Unlike the more common laboratory animals, we share our homes with dogs, breathing the same air and often even eating the same food. So identifying the specific triggers that cause cancer in one species will likely lead to better diagnoses and treatments in both.
Meanwhile, studies into dog genetics can sometimes tell us about our past as well what may happen to us in future. Elaine has recently published a study looking at genetic variation in a type of herding dog found on the Italian island of Sardinia, the Cane Fonnese (or Fonni’s dog). These dogs can show considerable variation in their appearance but all share the same behavioural traits – intense loyalty to their owners, a strong herding instinct and, more remarkably, a talent for stealing property from their neighbours.
Genetic analyses carried out by Elaine’s team and their Italian colleagues suggest
that the breed has the same ancestry as the Saluki, a sight hound that originated in the Middle East and the Hungarian herding dog known as the Komondor. She says that the results of genetic analyses in dogs may be of interest to students of human history, and not just veterinary and medical scientists.
“This work can shed light on the way that ancient human populations migrated around the Mediterranean basin when there is a shortage of conventional archaeological evidence. That is not surprising when you think about it – because wherever humans have gone during the past 10,000 or more years, they have always taken their dogs with them.”
Nominations are currently being sought for the next awards which will be presented at a ceremony at the Kennel Club in London on 24th May 2017. With a prize fund totalling £65,000, the Kennel Club Charitable Trust is urging people to nominate themselves or their peers by 13th February 2017. The awards will be judged by representatives from the veterinary profession and the world of scientific research, including experts in each of the nominees' selected fields. For more information about how to apply visit the Kennel Club’s website now.