Skip to main content

Signs of inbred dogs – and all the reasons why inbreeding is controversial and problematic

Here's how to spot indicators of inbreeding (and what to do if you have an inbred dog)

A close-up shot of a black Lab wearing a red collar
jevelin / Shutterstock

Inbreeding, or the act of deliberately breeding two related animals together, is a controversial topic. Sadly, inbreeding is all too common in the world of our canine companions. According to a veterinary study conducted by the University of California at Davis, scientists discovered an inbreeding level of roughly 25% — the same amount of genetic similarity between siblings.

Many dog breeders intentionally choose to inbreed dogs to strengthen certain physical and behavioral traits, as well as to keep the breed’s bloodline pure. But this pure bloodline comes at a cost. We’ll go over the five most common signs of inbred dogs and discuss why each is potentially dangerous for these unfortunate pups. 

Newfoundland dog lying down
Angel Luciano / Unsplash

What does an inbred dog look like? 

You may wonder if any of the signs of inbred dogs are easy to spot by appearance. Certain dog breeds are renowned for possessing specific traits. From the French bulldog’s precious face to the German shepherd’s trademark stance, dog breeders have relied on selective breeding for centuries. Unfortunately, some physical signs of inbreeding aren’t as endearing as the Frenchie’s stunted snout.

Inbreeding not only results in reduced litter size, but it also leaves inbred pups smaller than non-inbred dogs of the same breed. In some cases, inbred dogs have asymmetrical features, ranging from eyes of different sizes to misaligned jaws. Inbreeding also makes dogs much more likely to develop a genetically predisposed disorder at some point during their life.  

A German shepherd lying on his side in a yard.
imsogabriel / Pixabay

Can a vet tell if a dog is inbred? 

When it comes to determining the degree of inbreeding in a given pup, the experts use a method of calculation called “the coefficient of inbreeding,” or COI, developed by Sewall Wright in 1922. The most inbred dog breeds on record are Norwegian Lundehunds, pugs, English bulldogs, basset hounds, golden retrievers, Labrador retrievers, and boxers.

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. However, as we mentioned earlier, inbreeding can leave behind physical clues. If a dog from a breed known for being inbred is small for his breed, has congenital birth defects, or shows symptoms of having special intellectual needs, it’s highly likely that inbreeding is a contributing factor.  

Litter of nursing puppies
Karen Dole / Shutterstock

What is inbreeding vs. linebreeding?

So long as you aren’t the one breeding dogs, you don’t need to know the particulars of mating selection, but it’s good to have an idea about acceptable practices. Unlike inbreeding, linebreeding means you specifically don’t mix closely related animals. As in, you would never put together two pups from the same parents or even grandparents.

Instead, breeders look to pick dogs that have a more distant relationship but still have similar traits — it’s basically the equivalent of you marrying your second cousin. While there’s no way to totally rule out some of those negative recessive traits any time you try to mate dogs of the same breed, linebreeding certainly assuages many of the fears and can reduce the prevalence of birth defects.

A Sheltie backlit by the sun walks across the pavement.
Ahmed / Adobe Stock

What problems do inbred dogs have?

Not only does inbreeding cause health issues, but inbred dogs are also more likely to display behavioral problems than outbred dogs. Here are the five major signs of inbred dogs.

#1: Damaged DNA makes health problems more likely

Inbreeding results in broken genetics. The three forms of harmful mutations (additive, dominant, and recessive) are easily bred out of dogs with greater generic variance, especially when it comes to a damaged sequence responsible for recessive genetic traits. With inbred dogs, a damaged — or broken — genetic sequence is passed down by both parents. 

#2: Inbred dogs tend to have fertility problems

According to the Institute of Canine Biology, dog breeds with greater than 5% inbreeding are at an increased risk of reduced fertility and smaller litters. Unfortunately, there are very few dog breeds without high degrees of inbreeding. Shockingly, it’s estimated that only 20 breeds in the world have less than 25% inbreeding in their genes.

#3: The strange phenomenon called “inbreeding depression”

Inbreeding depression, known as “an unspecific decrease of fitness,” drastically reduces the quality of an inbred dog’s life, leading to higher incidents of mortality in puppies and shortened lifespans due to a weakened immune system. Common health issues include neurological conditions, skin problems, gastrointestinal matters, and joint problems, such as hip dysplasia.  

#4: Inbreeding can lead to aggression

Inbred dogs tend to be less intelligent than other members of their breed, and while it’s not always the case, inbreeding can lead to higher rates of behavioral issues. Aggressive behaviors, such as rough play, snapping at or biting people or other animals, and even serious attacks are all more common in inbred dogs. 

#5: Inbred dogs are more likely to suffer from anxiety

In addition to aggressive behaviors, inbred pups are more likely than other dogs to have personality disorders. Severe separation anxiety, impulsive behaviors (compulsively chasing vehicles or running out into the street), fearfulness, and even a complete lack of affection for their human family are all more common in inbred dogs. 

Happy golden lies down on the pavement to get pets
Laura Stanley / Pexels

Do inbred dogs live long?

That’s relative. However, inbreeding does shorten a dog’s life, according to research. A recent study from 2021 found that there were significant differences in life span between pups that had low levels of inbreeding versus ones with high levels of inbreeding. Other estimates put the reduction in the life span of an inbred dog at 6 to 10 months shorter than had they not been inbred.

What’s more, inbred dogs are more likely to have health problems that can decrease the number of years you have with them. You can’t always control whether your dog is inbred — all you can do is give them the best life possible and keep an eye out for health issues. However, it’s best to avoid contributing to the issue of inbreeding.

While many dog breeds have high degrees of inbreeding, some are worse than others. If you want to ensure that your new pup is as healthy and well-adjusted as possible, we recommend thoroughly researching breeders and requesting a genetic COI before you purchase a puppy. Another great idea? Try your local animal shelter. You’d be surprised by how many purebred dogs you can find right around the corner. (And don’t forget about mutts! Some of the best dogs are mixed breeds.)

Editors' Recommendations

Mary Johnson
Mary Johnson is a writer and photographer from New Orleans, Louisiana. Her work has been published in PawTracks and…
Coconut oil for dogs: The pros and cons you need to know
What are the benefits of coconut oil for dogs? It's complicated.
Coconut oil next to a coconut

If you've followed human wellness and nutrition trends over the years, you likely know olive oil is the golden child of oils. Lauded for being a healthy fat that can protect against heart disease, even cardiologists recommend consuming olive oil. Yet, coconut oil has also come into favor recently for health benefits ranging from weight loss to immune system and improving cognitive functioning in people with dementia. Keyword: People.

What are the benefits of coconut oil for dogs? Are there even any? Is coconut oil safe for dogs? These are all excellent questions and ones to ask a vet before giving any human food to a pet, whether you're allowing them to ingest the item or applying something topically. Some foods are toxic to pets, and topical application of some products can exacerbate the issues you want to fix. Where does coconut oil fit in? Here's what we do (and don't) know about coconut oil for dogs.
What is coconut oil?

Read more
Can you give a dog Benadryl? You’d better follow the correct dosage guide
Antihistamines can work wonders for pets with allergies
A golden retriever wearing a scarf and holding a handkerchief in his mouth

Just like us, dogs can suffer from allergies. While we can use a nasal spray or take an allergy medication, our dogs rely on us to treat their symptoms. Diphenhydramine, the generic name for the widely used name brand Benadryl, is commonly prescribed by veterinarians to treat seasonal allergies, anxiety, and even motion sickness. Have you ever wondered, "How much Benadryl can I give my dog?" We'll walk you through everything you need to know about giving dogs Benadryl, from the correct dosage to potential side effects.
Benadryl dosage for dogs 

Always speak to your vet before giving your dog any medication or supplements. Because your vet knows your pup's medical history, they can make the proper recommendations. Benadryl should not be used if your dog:

Read more
Can dogs eat avocados? What to know before snack time
Why you want to avoid giving dogs avocados as a treat
Corgi with an avocado

Avocados are a favored food for humans. Full of vitamins, minerals, healthy fats, fiber, and even protein, and they've risen to "superfood status." Avocado toast? That's a favorite brunch choice, apparently of Millennials (but really, of people of all ages). You may want your dog to enjoy the same benefits, including the creamy texture and so-good taste.

As humans, we often love sharing some of our beloved foods with our pets. Sometimes, these foods are just fine for a healthy dog to have in moderation. However, some foods are toxic to dogs. Where do avocados stand? Can dogs have avocados? Sadly, avocados are not a safe food for dogs. Here's why and what to do if your dog consumes a piece (or whole) of avocado.
Can dogs have avocados?

Read more