In some cases, these health problems have occurred as by-products of consanguinity. Because breeds are genetically closed populations, a mutation causing the disease that simply appears in a dog can quickly become common in future generations. “Especially if the animal with this mutation is also a price specimen,” said Dr. Serpell. “Because everyone will want to reproduce this individual.”
The result is that many modern breeds suffer from ailments for which dog lovers would never have been deliberately selected. Labrador Retrievers is subject to a degenerative eye disease known as progressive retinal atrophy, while Cavalier King Charles Spaniels often develops heart disease called Mitral Valve disease.
In other cases, however, the physical features that breeders are looking for can be the problem, especially since these characteristics are more and more exaggerated. The Bulldogs breed standard explicitly calls for “very short” snouts, but over time, dog snouts have practically disappeared, said Dr. Serpell, leading to serious respiratory problems.
Mutts and dogs with a mixed breed can be healthier than those of pure breed, especially if they have small amounts of DNA many different types of breeds, said Dr. Bannasch.
But some mixed dogs can still be very consangurated, she said, and certain health problems are common in several breeds. Many large breeds are subject to bone cancer, for example; Mixing some of them together may not have many advantages. “You cannot group all the” mixed races “,” she said.
The link between race and behavior is more troubled.
By creating modern breeds, humans generally put a much stronger accent on appearance than on behavior, which is also shaped by the training of a dog and the early environment.
“The behavioral features certainly vary from one race to another, but not as strongly as morphological features,” said Dr Boyko. “You will never have a collie that looks like a great Danes,” he added. “But I see that many dogs have a pointing behavior that are not pointers.”
Scientists have discovered certain general models. Burrows, who were raised to hunt and kill pests, are more likely to show “Chasing predator” that farming dogs, for example. And, on average, the Siberian Huskies are more likely to howl than the retrievers of Labrador.
But, on the whole, Breed is a bad predictor behavior, and there is more variation within the races than between them, have discovered scientists. Someone who wants a sympathetic dog and lists of offer that does not bother cannot be set up to get exactly that simply by bringing a Labrador Retriever to the house. “You can get exactly the opposite of that,” said Dr. Lord.