The latest craze among dog lovers is the designer hybrid, but there is a downside to messing with dog DNA. Veterinarian Pete Wedderburn on how to choose a puppy
On the streets of New York, London, Paris, and yes, even Dublin, the latest must-have accessory is the designer dog, also known as a "dog hybrid". It is a deliberate cross-breed between two pedigree breeds of dog, with the intention of obtaining the best of both breeds. The resulting breed-mixes have carefully coined names to add to their appeal: Labradoodles, Peke-a-poos, puggles, Labradingers and cockapoos.
The theory behind designer dogs seems logical: if you mix two different pedigree breeds, you hope to produce puppies that have the best qualities of each of their parents, and a lower likelihood of the inherited diseases that plague some breeds. The term "hybrid vigour" (or "outbreeding enhancement") describes the extra health and vitality that is hoped for. However, there is a risk that is often forgotten. You may end up with the worst of both breeds - a phenomenon known as "outbreeding depression".
If a pug was crossed with a Pekinese, you could end up with puppies whose eyes protrude so far that they literally fall out. Or if a Newfoundland was crossed with a St Bernard, the huge progeny could have debilitating heart disease or crippling arthritis. The problem with designer dogs is that genetics is a complex game of chance. You could be taking a big gamble, especially if you are mixing breeds which represent the extremes of the normal range of domestic dogs.
In the world of pedigree breeding, there is always the risk of a puppy developing diseases inherited from its parents. If you open a standard veterinary text book, you will find a long list of the conditions that are common in different breeds. Examples include arthritis, blindness, non-functional kidneys, liver disease, heart failure, breathing problems, psychiatric disorders, itchy ears and skin disease.
Why are pure-bred animals prone to these diseases? The answer lies in the genetics of breeding. In nature, "survival of the fittest" is the basic law. Individuals that are stronger, healthier and more vigorous than their siblings are more likely to survive and breed. As a consequence, the "weak" genes that make animals prone to disease are weeded out.
In the dog-breeding world, humans have taken over nature's role. Dog breeders select the animals that are used for breeding, and their criteria may be very different from the simple "survival of the fittest". To produce puppies with a particular physical appearance and personality, you need to deliberately breed from dogs that possess those qualities. However, as well as possessing the desired attributes, the resulting puppies may have other, less desirable qualities, such as vulnerability to inherited diseases that may not become obvious for several years.
The authorities which represent the dog breeding world (such as the Irish Kennel Club) are very aware of breed dispositions to certain diseases, and they are working hard to solve the problems. There are screening programmes in place, with the aim of removing some of the worst inherited diseases from the breeding pool. If you plan to breed from a golden retriever, you should have her hips and elbows X-rayed and analysed by experts. If she has healthy joints, she is given a good rating, and if she has joints that are more likely to develop arthritis later in life, she is given a bad rating. If you choose a golden retriever puppy from parents which both have good ratings, then you are much more likely to have a dog that matures with healthy, arthritis-free joints.
Similar screening programmes are in place for other breeds with a tendency to arthritis, and for certain types of inherited eye problems. The latest genetic technology is now being introduced to develop even more advanced methods of screening. An international research programme known as the Dog Genome Project has mapped out a detailed genetic analysis of the domestic dog.
Recent screening trials involve analysing the genetic make-up of a large number of animals to try to pinpoint the genetic background to known inherited problems. If this information can be obtained for a particular disease, the best animals for breeding can be identified through a simple laboratory test carried out on a blood sample or a mouth swab. Already, more than 15 diseases can be screened out using the latest DNA tests.
Many breeders already have a good understanding of genetics. If you look at any pure-bred dog's pedigree, you will see a map of an individual's genetic background over half a dozen generations. The rapid turnover of dog generations, combined with the careful record-keeping associated with pedigree animals, means that it is relatively simple to follow the course of genetic problems. If a dog has a particular inherited disease, it is easy to identify all of his cousins, and even his second and third cousins, once, twice and three times removed.
At the start of 2006, the Irish Kennel Club introduced compulsory microchipping by breeders of all pedigree puppies. This means that all pedigree dogs are now bar-coded with a unique 15-digit number, easily retrieved by waving a wand-like scanner over the dog's back. The resulting data is stored on a central database. This will make it easier to track genetic problems in Irish pedigree dogs in the future.
This may be interesting and useful for dog breeders, but for ordinary families choosing a dog today, simple questions need to be answered. What should a puppy-shopper do to minimise the risk of acquiring a dog with problems? Overall, pure-bred pedigree dogs are often the best pets to choose, because the size, appearance and temperament of the adult animal is much more predictable than the unknown potential of a mixed-breed dog.
However, the unavoidable downside of all pedigree dogs is the increased risk of inherited diseases. To minimise this risk, you should ensure that your new puppy has parents that have been screened in the appropriate way for their breed (for example, X-rays of hips have been done and eyes checked). Contact the Irish Kennel Club to ask about the screening programmes for a particular breed.
You should also ask the breeder if you can meet the mother and the father of your puppy. If both parents are healthy, good-natured individuals, there is a higher chance of your pup turning out well, although this does not remove the need for proper genetic screening. A good-quality pedigree dog does not come cheap: expect to pay between €400 and €1,000, depending on your choice of breed.
For financial and other reasons, many people still choose a cross-bred dog. Thousands of unwanted dogs are destroyed every year in Ireland, and it can be rewarding to give a home to such an animal. You do need to be aware of the potential problems involved in rescuing a dog. An adult dog from an animal sanctuary may have been rejected by its original home for many reasons, both physical and behavioural. Check with the sanctuary that they will give you support if you run into difficulties that you cannot handle.
If you choose a cross-bred puppy, it is often difficult to meet both parents, but do at least try to meet the mother. The upside of a cross-bred puppy is that it is less likely to develop inherited diseases than a pedigree animal. The downside is that the adult animal will be much less predictable than a pedigree dog.
So is there a place for designer dogs? To increase the predictability of the adult version of a puppy, a cross-bred pedigree dog can indeed be an excellent idea. But you don't need to choose a trendy made-up breed with a cute-sounding name. Ask around locally, at vets and animal rescue centres. Find out what puppies are available in your area, and if there happens to be a cross-bred pedigree litter of pups, they could be the ones for you. If the pedigree parents have been screened for inherited diseases better again.
Finally, whatever you choose, take your new arrival to the vet as soon as possible. If a problem exists, you may be advised by the vet to send the puppy back to the breeder. If small, cuddly creature has been in your home for a week before you discover the problem, there is little chance that you will be prepared to send him back to an uncertain fate. Inherited problems such as heart murmurs and hernias may be invisible to owners, but can have devastating effects on the future health of the dog. It is important that they are identified as soon as possible. As well as checking the physical condition of the young animal, the vet will also give you good basic advice on caring for the puppy.
If you are reading this and thinking "why bother with all the trouble of a dog", remember the words of Rudyard Kipling, which apply to every dog, regardless of its breeding: "Buy a pup, and your money will buy love unflinching."
Pete Wedderburn is a vet at Brayvet, Bray, Co Wicklow and a media commentator on veterinarian topics. Further information on pedigree dog diseases from: www.vet.cam.ac.uk/idid/ and http://handicappedpets.com/genetic/diseases.htm