These crosses are generally just a way for irresponsible people to make money
Sadly in the UK it is rare for breeders to issue neutering contracts or endorse pedigrees, or even to discuss with their puppy buyers about breeding - the costs financially and emotionally. The mixes that really scare me are things like Akita cross German Shepherds - and I have now even seen them crossed with Rottweilers - just crazy, mixing large, powerful and very clever dogs.
Shelters and rescues are full of crosses with all sorts of health issues because they are poorly bred, from poor stock to start with, and generally poorly reared and end up with all the problems of backyard or puppy mill bred dogs.
...while there is the possibility of hybrid vigour, there is also the chance of getting all the worst elements. Eg a puggle whose eyes come out, as pugs' eyes sometimes do
Given the fact that most designer crossbreeds are not coming from very health-focused stock in the first place -- only rarely would a dog slip through the net into such hands from the breeders who do focus on health, and most breeders of same certainly are not after improving any breed but of making very large amounts of money off of some of the same crossbreeds you can get for free in shelters or see being given away free in classifieds. Advertised blatantly as 'designer dogs just like [fill in B-list celebrity name] owns'...
Also
there is no stability of temperament in any cross -- which is one of the reasons people go for purebreds in the first place. Any cross may have the personality of one or the other of its parents, or a mix -- but again, if the parents are of indifferent stock where the breeder has never bothered to breed for temperament, you aren't going to get a cross between the liveliness of a beagle and the good nature of a pug. You may well get the obstinacy of a beagle and the yappiness of a pug.
If any of these new mixes were to be recognised of course they would likely look much different than they do now once they breed true, and of course after that first generation cross they no longer have any immediate health benefits, according to research. Once the gene pool is restricted to those breeding true in the new breed, it too becomes a purebred with all the genetic implications that implies.
On the other hand, serious problems in all breeds have developed since the advent of the formalised dog show and breed competitions in the late 19th century. Two world wars really winnowed out the gene pools of many breeds too, including the cavalier, which was drastically affected by WW2 in the UK. A lot of genetic diversity was lost when breeders stopped breeding because of the wars.
by Karlin in a previous discussion on this topic, following a link to this article
http://www.prweb.com/releases/2006/5/prweb379585.htm
Because of genetics, no dog regardless of breed or cross is safe from inherited health issues. A big myth that many less than ethical breeders of both purebreds and designer mutts will use is that their dogs are genetically free of all health issues. (Please for more on this topic, read reknowned canine geneticist Dr. George Padgett's article in Dog World from January of 1997 where he discusses the over 102 genetic issues that cross bred dogs can have). Hybrid vigor does NOT exists in the crossbred dog or the world of domestic dogs regardless of what anyone states.
Well, first, many health issues have no genetic test - just screenings. But even with this knowledge, a good breeder will screen potential breeding dogs. Since there are many health problems that can be found in various and even all breeds, no breed or cross is safe from them. It is up to the breeder to screen for what they can and have the dogs certified where applicable (such as OFA - Orthopedic Foundation of America).
http://home.comcast.net/~NoPuppyMil...Mutt/health_issues_in_designer_mutt.html#labs
Please click on the breeds in the cross/designer mutt you are looking at. Compare the lists and you will get an idea of what the cross can inherit. Please note that the lists of inheritable issues are not complete. Just the more common hereditary or possible hereditary health issues are listed. Also note, that some things most assume are not hereditary may actually have a hereditary basis like predisposition to ear infections and allergies or a predisposition to the often fatal problem of "bloat." Hips dysplasia is found in all breeds of dog from tiny to giants. It was discovered no longer to be a "big dog" problem. Even if it is not listed under the breed you are checking, please note that no breed or cross is immune from this hereditary issue. Any breeder should at least OFA or PennHip certify their dogs along with CERF and Thyroid. And:
The Myth of Hybrid Vigor in Dogs
by Karen Peak
The concept of hybrid vigor assumes that a crossbred animal (and this term is most often used in discussing dogs) will be healthier than a purebred. In reality, this is often false.
In order to be a hybrid, an animal must be the product of two different species: donkey and a horse, offspring is a mule; lion (m) and a tiger (f), offspring is a liger; tiger (m) and lion (f), offspring is a tigon; wolf and domestic dog, offspring is called a wolf hybrid. Remember high school Biology, animal classification: Kingdom, Phylum, Class, Order, Family, Genus, and Species? Each animal in the crosses mentioned share the same Family (Equus, Felis, Canis) but are different species. The offspring are hybrids. Domestic dogs are the same species familiaris. When you cross breed domestic dogs (Canis familiaris ), you are within the same species; therefore, not creating a hybrid.
Hybrids are not problem free. In Ligers, no fertile male has ever been found and necropsies have proven sterility in them. Other issues in ligers and tigons: ligers may be prone to gigantism and tigons may be prone to dwarfism. Both hybridizations have shown an increase in cancer rates and decrease in lifespan. (Tiger Territory, M. Annabell, 2001). In wolf/dog hybrids, there are often behavioral issues. The domestic dog differs greatly in behavior from a wolf. Dogs were bred to be cooperative with humans while wolves fear humans and try to avoid us. Even domestic Wolves are far different from dog in terms of behavior. Dogs often accept leadership happily while adult wolves will fight for leadership within the pack. The wolf/dog hybrid can be a time bomb temperamentally when they hit full maturity. Wolves also differ from dogs in other ways including: skull structure, nutritional needs, estrus cycles, etc. (Canine Hybrid Issues Surrounding the Wolf Dog , M. Sloan, J. Moore Porter, 2001)
Returning to the domestic dog: Canis familiaris. A breed is not a separate species, it is just a set of genes specifically bred to exhibit certain traits like the coat an Old English Sheepdog has or the build of a Rottweiler. With C. Familiaris, we just took traits in dogs of the same species and developed them to various breeds. An example that may clarify this: all humans are Homo sapiens regardless of color, eye shape, etc. Nature helped develop certain traits to best suit the environment the H. sapiens were developing in. All domestic dogs are C. Familiaris; we just developed them into different breeds. Species is the same but there are differences based on need.
What determines a breed in the loosest sense is that when bred to another of the same breed, you will end up with the same traits. When you breed a German Shepherd Dog to another GSD, you only get GSDs. You will not get something that looks like a Labrador Retriever. If you cross a GSD and a Lab, you can get offspring that look more GSD, more Lab or resemble both parents in varying ways. With purebreds you have a predictable outcome. With crosses, you do not. It takes many generations to fix the traits in a new breed – not just four or five. For example, the Shetland Sheepdog, a breed from the Shetland Isles is NOT a miniaturized Collie. But the Sheltie is a breed that is only about 100 years old – relatively new. Collie was crossed into the early Sheltie to add to certain traits, but this also added the problem of oversized Shelties – something breeders have struggled with for many decades to correct due to the infusion of Collie blood into a developing breed.
Crossbred dogs such as the Cock-a-poo are NOT hybrids nor are they breeds. The Cock-a-poo Club of America states in its guidelines that in order to be a cock-a-poo, that you breed Cocker (American or English) to a Toy or Miniature Poodle. This is not a breed; it is a cross – a mutt. Cock-a-poos may look very Poodle, very Cocker or somewhere in between. Even a Cock-a-poo bred to a Cock-a-poo is not a breed. Remember, it can take decades or more to get true-breeding traits – or to repair damage done when something else is crossed in during the early history of a breed just beginning to come together.
There is research that states the domestication of what we know today as a dog may have started longer ago that assumed – maybe as much as 100,000 years ago based on mitochondrial DNA studies of wolves and dogs. (The Truth About Dogs, S. Budiansky, 1999) No one really knows for certain when wild canines began domesticating themselves or we began domesticating them. Therefore, the creation of specific breeds is relatively new in the grand scheme of the history of the domestic dog. Bones of truly domesticated dogs were found dating back to as early as 5,000 BC. Ancient pictures show dogs that were of definite sight hound type. (Dogs of Ancient Egypt, J. Dunn).
Back to Hybrid Vigor: is it true? No. Returning to the cock-a-poo example. Poodles and Cockers have many of the same health problems; therefore, a cross of them might actually stand a higher risk of inheriting a problem than a purebred pup from a good breeder. Some of the problems in both breeds are: hip dysplasia, progressive retinal atrophy, epilepsy, poor temperaments, allergies, skin and ear problem, Legg-Calve-Perthe's, luxating patellas, hypothyroidism, cryptorchidism, gastric torsion ( Cock-a-poos, Cindy Tittle Moore, 1997). Yes, things like ear infections, allergies, temperaments and gastric torsion have hereditary as well as environmental influences.
Now, why did I state a cross might stand a higher risk of a hereditary problem than a dog from a good breeder? Rarely do people breeding crosses do any health tests – genetic or otherwise. They assume that an annual veterinarian visit and shots are all that is needed. Maybe for a pet dog, but breeders need to consider the genetic health of puppies produced. Things such as Hip and Elbow Dysplasia, Luxating Patellas, various eye problems, von Willebrand's (a bleeding disorder) and Thyroid function are common in many, many breeds and crosses. The myth that purebreds are unhealthy or nasty came about due to bad breeders who either did not care about health testing or who were ignorant and felt that dogs who show no outward signs of a problem do not have it. A purebred dog from a good and educated source has a greater chance of being healthier than a crossbred.
So, the next time you hear about hybrid vigor and how mutts are healthier, remember this: hybrid vigor as related to dogs is a myth.
FMI on hybrid vigor and how it is misused in dogs, please read:
http://www.bullmarketfrogs.com/pages...ngprograms.htm
http://www.bulldoginformation.com/breeding-myths.html
