Hepper is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

6 Consequences of Inbreeding in Dogs – What You Need to Know!

Kathryn Copeland

By Kathryn Copeland

Lab Puppies Climb Out of Brown Wooden Crate

It’s likely we’ve all heard about the adverse outcomes that occur with human inbreeding. In fact, there are laws against inbreeding in most countries around the world, but there aren’t any laws preventing it with dogs.

It’s often said that mutts are much healthier than pedigree dogs because of inbreeding, but is this actually true? We’ll explore the ins but mostly outs around the subject of inbreeding dogs and the consequences when humans interfere.

There are many scientific terms and explanations on inbreeding floating around out there. However, we’re going to keep this article as simple as possible for those of us whose brains shut down over the complicated explanations of things.

divider 10

What Exactly is Inbreeding?

Before we begin, we need to have a better understanding of inbreeding. In a nutshell, inbreeding is when puppies are bred from two related dogs. These dogs always have relatives in common, such as mating the siblings or breeding the parents with their offspring together.

This produces dogs that all have almost identical genes, and this is how many of the current dog breeds have come into existence.

dachshund puppies
Image Credit: ch_ch, Shutterstock

How About Linebreeding?

Linebreeding isn’t quite as extreme as inbreeding. It involves breeding dogs that share the same bloodline, such as grandfather with granddaughter or uncle with niece.

Technically, this is still a form of inbreeding, but the relatives don’t tend to be as directly related. This practice isn’t quite as bad for the dogs as inbreeding, but there are still issues that crop up.

Divider 2

Why Do Dog Breeders Use Inbreeding?

It’s all about the breed standard. Breeders look to breed their dogs to have the best qualities and breed standards in their dogs. If a breeder has a dog that is a perfect example of that breed, they will want to encourage that perfection by breeding that dog with another that shares the same qualities. And this is usually found within a close relative.

It’s even more of a bonus if they can breed champions found within the bloodlines as the more champions kept within the same bloodline, the better the pedigree for upcoming litters.

This kind of breeding can also allow the breeder to “breed in” the good qualities and “breed out” the bad.

These “perfect” dogs can potentially do well in the show ring, and their pedigree can increase the value of their litter. When advertising their puppies, the number of champions found within their bloodline will increase the price, regardless of their health and conformity.

white west highland terrier puppies
Image Credit: LanKS, Shutterstock

What Does the Coefficient of Inbreeding Mean?

We can’t discuss inbreeding or linebreeding without having a look at the coefficient of inbreeding (COI). Yep, science. But having a basic understanding of this concept is a necessary evil, particularly if you’re interested in purebred dogs.

It’s essentially a term that is used to describe how closely related two relatives are. So, the higher the coefficient of inbreeding (COI) is, the closer the relationship, and conversely, the lower the COI, the more distant the relationship. So, for example, the closer relationship between mother and son is 25% COI, and the more distant relationship between two first cousins is 6.25% COI.

Some of the more common COI are:
  • Mother/son: 25%
  • Brother/sister: 25%
  • Father/daughter: 25%
  • Grandparent/grandchild: 12.5%
  • Half-brother/half-sister: 12.5%
  • Great-grandparent/great-grandchild: 6.25%
  • First cousin/first cousin: 6.25%

These percentages tell you how close the relationship is between the dogs being bred and consequently the likelihood of a dog becoming ill. It’s known that the higher the COI, the higher the chance that the puppies will develop inherited disorders.

Divider 8

The 6 Consequences of Inbreeding

There are a number of reasons why inbreeding/linebreeding can have serious consequences for our dogs. One of the worst aspects of inbreeding is that it can sometimes take a number of generations before the detrimental aspects of the inbreeding actually show up. You might end up with litters with a higher than usual proportion of stillbirth puppies or suffering senior dogs, which may or may not be a product of inbreeding, but most often is.

1. Small Gene Pool

When it comes to purebred dogs, the gene pool is getting smaller. A purebred dog is registered as purebred if both the dam and sire are also purebred, which keeps going back until the founding breed.

Another aspect of the purebred registry is that not only are the gene pools small, but they are also usually closed. A closed gene pool occurs when purebred dogs are only allowed to breed with existing breeds without the introduction of new blood and genetic material from much healthier breeds.

malteses puppies in a basket
Image Credit: haidi2002, Pixabay

2. Inbreeding Depression

Inbreeding depression occurs when too much inbreeding causes lower fertility and mortality rates, and the offspring become less robust and lack vitality. It can reduce litter size, increase the likelihood of health problems, and the dogs might develop undesirable temperaments.

3. Physical Issues

With inbreeding, we have gotten dogs like the Bulldog. Because of their pushed-in noses, they commonly suffer from breathing difficulties (Brachycephalic Airway Syndrome). Other dilemmas can occur, such as issues with slow growth and even problems with asymmetry, such as one eye sitting higher than the other.

bulldog puppy
Image Credit: Ilona Krijgsman, Pixabay

4. Genetic Defects

There are a large number of breeds that tend to suffer from the same health issues. For example, the Golden Retriever is prone to hip and elbow dysplasia, the Beagle is predisposed to heart disease, and glaucoma is associated with the Basset Hound.

This means all of these breeds have been inbred long enough to make these health issues commonplace, so when you buy that Golden Retriever puppy, she might just develop hip dysplasia as she grows up.

5. Shorter Lifespans

Yet another consequence of inbreeding is that purebred dogs generally have shorter lifespans. The shorter lifespans result from the aforementioned genetic illnesses that are passed on to the dogs but are also because they typically have weakened immune systems. Inbred dogs are already prone to weakened immune systems because of the loss of vitality.

Image Credit: Joe007, Pixabay

6. Increased Genetic Diseases

The less bred the animal, the less the genetic diseases. For example, a coyote has 3 genetic diseases, a cat has over 300, and a dog has over 600! Because the breeding of healthy dogs with these champion bloodlines remains closed, these inherited diseases will continue to affect these purebreds.

Divider 3


Hopefully, this article has given you a little knowledge of some of the inherent problems with inbreeding dogs. A certain amount of inbreeding is almost necessary if we want to keep some of these unique breeds of dogs around, but there are clearly issues around it.

Disease, health problems, unhealthy inherited traits, smaller litters, shorter lifespans, even negative temperaments are all issues that go hand-in-hand with inbreeding.

Using a Coefficient of Inbreeding calculator before breeding dogs is one way to determine if a particular mating will give you healthy puppies. However, in the long run, isn’t a healthy dog with a fantastic temperament always more attractive than a good-looking dog with health problems?

See Also: Chest Bone Deformities in Dogs (Vet Answer)

Featured Image Credit: Brook Robinson, Shutterstock

Related Articles

Further Reading

Vet Articles

Latest Vet Answers

The latest veterinarians' answers to questions from our database