Not all dog breeds are alike in terms of health, however. Tamaskan Dogs, Barbets, Australian Labradoodles, Danish-Swedish Farmdogs, Mudis, and Koolies were some of the least inbred, and they had rates of vet care comparable to mixed-breed dogs.
The highest level of inbreeding by far (> 80%) is for the Norwegian Lundehund. This breed suffers from extremely low fertility and high puppy mortality as well as an often lethal gastrointestinal disorder.
25% = the genetic equivalent of a dog produced from a father to daughter mating, or the mating of full-brother/sister. More than 25% - inbreeding is accumulative, so if it has occurred to a significant degree over several generations, the inbreeding coefficient may exceed 25%
Inbreeding levels above 10% will have significant effects not just on the quality of the offspring, but there will also be detrimental effects on the breed.
According to PETA, the labrador retriever is the most overbred variety of dog in the United States. Not coincidentally, they are also the most popular dog in the United States.
All breeds have genetic diseases, as we discussed above, but certain breeds are, unfortunately, just too unhealthy to recommend. These mainly include brachycephalic breeds, including Frenchies, pugs, cavaliers, Shih tzus and other breeds, as well as certain giant-breed dogs.
Probably the most notorious breed on this list, the pit bull has a reputation for unpredictability and aggression, even against its owner or his family. State and local governments have been vigorous in restricting ownership of this dog with breed-specific legislation.
Vets know the likelihood of inbreeding is high when they encounter these breeds, but genetic testing, such as this genetic COI kit, is the only way to know conclusively just how inbred your dog is.
Inbreeding two closely related dogs can cause malfunctioning organs, cosmetic defects, and other abnormalities. While some congenital disabilities are manageable, others pose lifelong trouble for the dog. Many pedigree dogs born with any flaw are considered defective, so they won't be eligible for registration.
They created the “50/500” rule, which suggested that a minimum population size of 50 was necessary to combat inbreeding and a minimum of 500 individuals was needed to reduce genetic drift. Management agencies tended to use the 50/500 rule under the assumption that it was applicable to species generally.
So it shouldn't really be a surprise that the breed has accumulated a few genetic inconveniences along the way. Bull terriers are also prone to breathing problems, heart and kidney disease, deafness, and knee issues. Purebred dogs are all inbred because, well, that's what it means to be a purebred dog.
They found that on average, the more inbred an animal was (using its “true COI” measurement), the smaller the litter size. The least inbred dogs had an average litter size of 8 puppies, while the most inbred dogs had an average litter size of 6-7 puppies.
Astoundingly, the Devils Hole pupfish is so inbred that 58% of the genomes of these eight individuals are identical, on average.
They tend to be more nervous, aggressive, and unpredictable than outbred pups. Inbred dogs also show signs of having special intellectual needs so training them might be a tad more difficult than with others.
Inbreeding is deliberately and routinely practiced as part of pedigree dog breeding usually in an attempt to breed for a particular 'look'.
Approximately 0.2% of all marriages in the United States are between second cousins or closer.
The European Union Responsible Dog Breeding Guidelines and the Dog Breeding Reform Group state that breeders should avoid breeding from individual dogs whose combined coefficient of inbreeding (the combination of both parents), measured over at least 10 generations, is greater than 6.5% [5].
You need to keep the original sire and dam, too. Breed three generations of female puppies back to your original sire. This concentrates the blood. This is called line breeding since you are breeding in a line back to the original sire.
Offspring from a mother-son mating would, therefore, have a 25% chance of inheriting two bad copies of the mutations that have been passed down to the son. This is a greater than 100-fold risk compared to an outbred dog! Inbreeding in dogs has real consequences.
Animals only rarely exhibit inbreeding avoidance. The inbreeding avoidance hypothesis posits that certain mechanisms develop within a species, or within a given population of a species, as a result of assortative mating and natural and sexual selection, in order to prevent breeding among related individuals.
Inbreeding siblings also risks weaker immune systems, more prevalence of autoimmune disease, more aggression in offspring, and reduced intelligence. Coefficient of Inbreeding (COI) needs to be considered, and it is generally recommended to keep it no higher than 5%.
Labrador Retrievers, Cavalier King Charles Spaniels and Newfoundlands are among the safest dog breeds that are least likely to bite, new research has found. While any dog can nip, these breeds are known for their particularly sweet-tempered spirit as long as they are treated right.
1. American Pit Bull Terrier. The American Pit Bull Terrier is considered one of the most dangerous dog breeds – both in the U.S. and internationally. They are a very aggressive breed and have been known to attack and kill people.