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The domestic dog is arguably one of the most genetically diverse species on the planet, in fact the World Canine Organisation recognises over 300 individual breeds. Thousands of years of artificially selecting and breeding only the individuals most suited to the needs of humanity, rapidly produced a multitude of breeds with a body plan and temperament for every aspect of human society.
Selecting a puppy with a long pedigree family tree may seem the sure fire way to a perfect puppy.
Whilst in the main our requirement for dogs as working companions has lessened (assistance dogs aside), our obsession with pedigree and improving canine genetics is still just as prevalent as ever. The recent controversy and media coverage surrounding a spate of television documentaries highlighting the potential genetic difficulties inherent in the breeding of pedigree dogs demonstrates the emotive nature of canine genetics.
Even for those not involved in the dog-showing scene, purchasing a new puppy often involves a great deal of research into the family history of the new arrival to ensure its ancestors were as healthy as possible. It is well documented that many of the most common conditions found in our canine companions, such as hip dysplasia and allergies can have a genetic basis.
With all this knowledge and careful breeding, it might be thought that such issues would soon be confined to the past, however, research shows that our classic view of inheritance may not be as it seems, putting into question the way we breed our dogs.
Classically it was known that each parent in a breeding pair passed on its own ‘blueprint’ of genes to its offspring, so each puppy inherited half its genes from its mother and half from its father. Therefore, as long as each parent was healthy and free of behavioural issues, it was thought each puppy would all be born as a clean slate with the perfect set of genetic instructions that when nurtured with correct nutrition and socialisation, would produce equally perfect adults.
However, research has found that the blueprint of genes passed on to the next generation can be affected by the experiences (such as stress or diet) of the parents, both before and during pregnancy. Known as epigenetics (literally “on top of genetics”), the blueprint has genetic markers added to it which markedly effect the way any future offspring develop. These genetic markers can also be added to offspring as they develop in the womb, potentially moulding the young before they are even born.
The bitch may change the genetic switches of her unborn puppies whilst they are in the womb.
This is not confined to animals, parents of a Swiss town who endured famine were found to produce children with a greater chance of developing diabetes in adulthood. More recently, children who were in the womb in the vicinity of the atrocities of 9/11 are now presenting with a host of terrible stress disorders, despite not even being born at the time.
These findings suggest relying on good genes and socialisation may not always be enough to ensure our dogs develop into well-rounded individuals. Potentially, the diet, everyday experiences, stresses and socialisation of a dog’s parents, grandparents and even great grandparents, may influence its health and temperament.
Such epigenetic changes to the genetic blueprint may explain the seemingly increasing prevalence of canine allergies; atopic dermatitis, for example, has become a massive problem in the Labrador retriever, despite careful selective breeding.
The link with stress may have implications for those breeders who choose to breed in a kennel environment and certainly for the rightly maligned puppy farm. A highly stressed bitch is likely to produce puppies with lower stress tolerance as adults, despite careful socialisation. The quality of the care the bitch provides her pups may affect their brain development; research with rats found that pups that did not receive regular licking from their mothers, were anxious and had ‘anxious brains’.
The prevention of stressful experiences in the pregnant mother may also prove a challenge for those who breed in a home environment; it is well documented that hormones related to stress rise when dogs are left alone and may be influenced by the interaction of other family members. Every dog owner has, at some point, witnessed his or her dog’s upset while watching a heated family discussion or argument.
Firework season may also present an issue for even the most well socialised canine, as today’s fireworks become progressively louder. If fearful experiences felt by the bitch during pregnancy can cause negative long-term changes in the puppies, it might be preferable not to breed during these months or for those looking for a new puppy to take into account exactly when their new arrival was in utero.
The move towards more biologically appropriate nutrition for our canine companions is certainly a move in the right direction, however, it is known the absence of particular nutrients, especially during pregnancy, can have a profound effect on the genetic markers the young receive. In effect, a dog’s health may not just be determined by the food it eats but by the food its mother ate too. Can the legacy of a previously poor quality, allergen and preservative laden diet have already left its mark on our dogs’ health?
The lifestyle and upbringing of a puppy’s grandparents may influence its behaviour and health. Should a puppy’s family history become just as important as its family tree?
It is clear that changes to the genetic blueprint may occur with the experiences a dog has over its lifetime and that these experiences can be passed to the next generation. Whilst any thought of a genetic pill to wipe clean the legacy of the past is light years away, should we question the criteria we use when selecting a breeder or puppy? When asking to see the parents of a new puppy, should we in fact be asking to see their grandparents and great grandparents? Should we be asking for records of the diet, birth date and home environment of not just the parents but also the preceding generations?
Only time will tell, but it is true to say that in light of new genetic research, the science of dog breeding may never be the same again.