If you have ever researched dog breeding, you might have been surprised that there are a lot more laws and restrictions surrounding breeding than you might expect. There are many arguments for and against restricting who can breed dogs and what dogs are bred. One commonly claimed is that restricting breeding leads to inbreeding of dogs. How true is this? Is it a problem? What other arguments for or against restrictions are there?

Current UK Breeding Laws

If a person wishes to breed dogs, there are a number of laws and legislations they must obey. A breeder must be licensed with their local authority if they breed 3 or more litters of puppies a year, are advertising breeding or are selling dogs. Other factors may mean a local authority could class someone as a business that requires a licence too. Being licensed requires that breeders inform the local authority of all litters, are inspected by a vet to ensure the environment is safe for puppies, have enough staff, cannot hold more animals than their premises can fit, are checked annually, and more. There is also very specific guidance for kennels, fences, care of the dogs, ventilation and so on. The government website is pages and pages long!

These sorts of legislation are similar to that for other businesses, such as restaurants and hairdressers. And this makes sense, because someone breeding dogs for income is running a business.

However, there are a number of loopholes with these laws, including not selling the puppies but gifting or giving them away; not making enough income per year to qualify as a business; or covertly selling puppies on sites like Facebook, Gumtree and eBay. A person can also breed as many puppies as they want to keep (or to give away – there must be proof that no money was exchanged). Furthermore, they do not entirely prevent illegal breeding such as at puppy farms, or illegal importation of puppies from abroad. We’ve discussed both of these issues in previous articles.

All of these laws are in place to protect animal welfare: both individual breeding bitches, stud dogs and puppies; and dogs as a population by trying to reduce incidence of genetic diseases and deformities. 

What is Inbreeding?

Inbreeding refers to “breeding from closely related people or animals, especially over many generations”. The closest form of inbreeding is siblings mating or parents mating with children. In the human world, inbreeding is taboo for obvious reasons. But there are also scientific reasons why inbreeding is a problem, in both humans and animals.

We’ve discussed this before, but in brief, when two organisms breed, the offspring receives a mix of genes from each parent. Genes determine traits, like hair colour, height, chance of certain diseases, nose shape and so on. Some genes are recessive and will only demonstrate their trait if they are paired with another recessive gene. This means both parents must have the recessive gene for the offspring to have the recessive trait. This tends to make recessive traits rarer – a good example is blue eyes in humans. A person must have received both recessive blue eye genes from their parents to have blue eyes. Many genetic diseases are only present in a person or animal if they have both recessive genes.

Inbreeding means that two organisms with similar genes are having offspring. Because they have similar genes, there is an increased chance that their offspring will receive two copies of a recessive gene. In a single instance of inbreeding, the chance of this may be low. However, with repeated inbreeding over many generations, the chance of these recessive genes becoming more prominent rises. There are good examples in humans of isolated colonies of people who all had to interbreed, resulting in very high instances of otherwise rare genetic diseases. On top of this, general health, fertility and wellness also tends to decrease with inbreeding – this is termed ‘inbreeding depression’.

How this translates to dogs is that the more inbreeding, the greater the risk that rare harmful genetic diseases may be present in puppies

And this isn’t just a warning, we are already seeing it now. Many breeds have their own genetic diseases, likely as a result of inbreeding within small populations. Some examples are heart disease in Boxers, eye issues in Collies and hip and mobility issues in German Shepherds. One study estimated that UK Pedigree dogs have an effective breeding population of 40-80 for all breeds (except notably the Greyhound), meaning all of the dogs within pretty much every breed are so closely related, it’s as if there are only 40-80 individuals.

Even more advanced studies that compared the genes of dogs found many dog breeds have levels of inbreeding to the point that inbreeding depression will occur. It is worth noting that most of these studies have been performed in purebred and pedigree dogs, It can be assumed that mixed breeds are likely to be less inbred. (Though this may change, such as with cockerpoos. See our previous article on whether these dogs are a real breed or not).

Inbreeding in dogs is as such a high level directly due to human choices. We have an idea of what a pug or boxer or Labrador should look like (kennel clubs even have precise standards). So puppies born close to the ideal are selected for breeding, often with other ideal dogs who may be closely related. This results in the very small breeding population studies have demonstrated. On top of this, humans tend to select specific traits that are often detrimental to canine health, such as short noses, bulgy eyes or a sloping back. All in all, humans have done pretty awful things to dog genetics. 

Should We Allow Anyone to Breed?

So, with inbreeding proving to be so harmful to dogs, surely widening who can breed and how would increase the gene pool, reduce inbreeding and improve dogs’ health? There’s certainly a grain of truth in that argument. 

If breeding was not restricted to a very small pool of dogs, as UK breeds generally are, and opened up to more people and dogs, logically the risk of inbreeding, genetic diseases and inbreeding depression will be reduced. And indeed, studies have proven that introducing even a small number of outside individuals into inbred populations can have substantial improvements on the health of the population at large. 

Allowing more people to breed would also likely increase the number of crossbred dogs. Now, we’ve written articles on the health of purebred vs mixed breed dogs before, and the jury is still out on whether one is healthier than the other. But studies have shown that mixed breed dogs tend to live longer. We are unsure if this is because of reduced inbreeding or some other issue, but certainly it appears to benefit the health in some way. 

From a purely scientific point of view, opening up breeding to a wider population would increase the effective breeding pool; and thus reduce the incidence of genetic diseases in many dogs. However, the reality of this is not likely to be this simple.

Problems With Unrestricted Breeding

Breeding laws are in place for a reason. Before, anyone could breed dogs with no set standards, leading to immense welfare concerns for the bitches and puppies. Even now, illegal breeders continue these terrible practices at puppy farms. By opening up breeding to more people without checks, welfare will decrease. This leads to increased incidences of mastitis, caesareans, pyometras or maternal death in breeding bitches. In puppies, we will see higher rates of mortality, more parasites, more sick puppies and generally less healthy dogs. This will affect life expectancies.

For all their flaws, the UK Kennel Club is trying, albeit slowly, to change their standards and implement schemes to reduce genetic diseases and negative traits like brachycephalic faces (more on these schemes later). If people can breed without licensing, they are unlikely to use KC schemes, potentially leading to a larger risk of genetic issues. Of course, small breeding populations got us to this problem in the first place, so it goes both ways. But unrestricted breeding with no prior testing could introduce new issues into breeds. 

Thanks to social media and more people wanting pets (especially over the COVID-19 lockdowns), certain breeds have exploded in popularity. The Kennel Club reports that the number of French Bulldogs registered increased 10 times from 2009 to 2015. It was the third most popular dog in that year. Frenchies are popular on social media for their cute squashed faces and funny noises they make (both actually serious genetic deformities) and so people want to have one. This leads to people breeding more to cover the demand.

Unfortunately, many of the most popular breeds come with a number of health issues. With no restrictions on breeding, we may find that more and more unhealthy dogs are bred for their popularity, with no thought for the actual health of the dog. Some vets are even calling for certain breeds to be banned until their health is restored; so you can see how serious this issue is. 

As a final issue, the UK already has many unwanted dogs 

This has increased dramatically as lockdowns ended, and unsocialised, unsuitable dogs are no longer a fit with people’s lifestyle. Unfortunately, the more dogs there are, the higher number we find in shelters left abandoned. Unrestricted breeding would likely worsen this, putting a strain on already overworked charities. 


So what’s the answer? If restricting breeding leads to high rates of inbreeding and genetic diseases, but unrestricted breeding causes welfare issues and may still cause genetic problems, how can we solve the issue? There are a number of ideas that have been proposed to restore the health of dogs while maintaining breeding standards.

Inbreeding Coefficient

One is to ensure that before two dogs are bred, their inbreeding coefficient is determined (this is standard practice when breeding pedigree sheep or cattle, for example – so why not dogs? – Ed.). An inbreeding coefficient is an estimation of the likelihood that two dogs will produce offspring with similar genes. It requires extensive records of both dogs’ ancestors to be accurate, and is only an estimation – it cannot guarantee a puppy will or will not have a certain genetic disease. The other issue is that many dog breeding records only go back so far, especially in relatively new breeds – as one study stated, “If you don’t go back enough generations or if you don’t have information about some family lines, you’re likely to underestimate inbreeding.”

The UK Kennel Club has their own calculator on their website, where pedigree dogs can be matched for suitability for breeding – if the inbreeding coefficient is too high, it is advised (but not enforced) that these dogs do not breed. The KC does, thankfully, not register dogs bred with siblings or parents (except in ‘exceptional circumstances for scientifically proven welfare reasons’ – it is unclear what exactly these circumstances may be). Thus, even if a match has a high inbreeding coefficient, there is little, currently, to stop inbred puppies being produced. 

Genetic Testing

Where inbreeding coefficient is an estimate, genetic testing is a much more accurate way to compare two dog’s genes. The potential mother’s and father’s genes can be tested to determine how compatible they are, and if they are likely to produce genetic diseases in their offspring. The technology for this is relatively new but developing rapidly. You can even order genetic testing kits online (though their accuracy may be in question). The Kennel Club does offer their own genetic testing for specific diseases too, so that the risk of genetic diseases can be calculated. Both of these methods should be encouraged before all breeding. Genetic testing is sadly not mandatory either. 

Breeding Laws

There is actually some legislation that requires breeders to reduce inbreeding and ensure healthy litters – a licensed breeding business can apply to become a ‘higher standard’ business. This rewards them with a cheaper licence fee and less regular inspections. However, it requires the breeder to test all dogs for genetic diseases and only breed if the risk is low. It also requires that no breeding should take place if the inbreeding coefficient is over a certain limit – however, this does not have to be performed if the breeder ensures that the dog’s microchip is updated with the new owner’s details, likely an easier change to make. So there is some incentive for breeders to maintain higher breeding standards, but it is by no means mandatory or universal. 

New Laws

A radical idea may be to only allow registered breeders to breed dogs – this would mean it would be illegal for anyone to breed even a single litter for any reason, unless registered and inspected by their local authority and a vet. This would ensure that there are always minimum standards for breeding, all puppies can be traced, and it is easier to enforce new legislation to reduce inbreeding and genetic disorders. However, this quite draconian idea would also carry issues.

Where would the law stand on accidental matings? How can a person prove their dog became pregnant accidentally? Would making registration mandatory drive more people to underground breeding or illegal importation, where welfare standards are poor? Wouldn’t this restrict the breeding population even more, resulting in even more inbreeding? Would the penalties for breaking the law be fines, banning them from owning dogs or jail? Who would enforce it – the police, vets, local councils? How?

All of these are considerations that would have to be made for such a harsh law to exist, and it is unlikely something like this would ever be legislated, let alone enforced.

Relaxing Pedigree and Purebred Rules, and Widening the Breeding Pool

These recommendations, made at the end of several studies, are likely the best approach and the easiest to implement. Currently, kennel clubs only allow pedigree dog matings to be registered. This reduces the breeding populations to the small levels we are currently seeing. By relaxing restrictions to allow more ‘outbreeding’ with other similar breeds or non-pedigree dogs, healthy genes can be inserted into the gene pool, diluting the effects of inbreeding depression. The studies also recommend making it easier for international breeding to take place, so the gene pool widens further.

Another recommendation is also to limit the number of litters a single male dog can sire – just like in horses, dogs with proven lineage and good genes tend to be bred from a lot. This results in one dog being the father of hundreds of puppies, increasing the risk of inbreeding. By ensuring a single dog can only father a few litters, different sires would have to be found with different genes. 

Restricting Breeding Certain Breeds

As we’ve discussed above already, some vets are calling for specific breeds to be banned, or their breeding heavily restricted. Chief among these are brachycephalic dogs (short-faced dogs) like pugs, French and English bulldogs and other similar breeds. As we have discussed many times, although these dogs are cute, they carry a huge number of genetic deformities that are creating many dogs that are almost incompatible with life, every waking hour a struggle to breathe. While we generally don’t support blanket bans on specific breeds, the health of these dogs is so poor that there is an argument to be made for restricting breeding heavily until their health is improved – this cannot be done with close pedigree breeding, so kennel clubs will have to accept that outbreeding is necessary to create healthy animals (see retro-pugs for an example of someone doing exactly this).  


This final recommendation may again be difficult to both implement and enforce, but the framework is already there. Puppy farms and importation of young animals are already illegal, and breaking these rules can face a person with a hefty fine, a ban from keeping animals or even jail. Could we expand laws to include bad breeding? Perhaps with some of the other solutions implemented, breaking these guidelines could become a criminal offence? For example, if you breed two pugs with awful nose conformation, having made no attempts to minimise this with genetic testing, this could result in a fine. Again, it’s quite draconic, but may be the most effective solution to ensure poorly dogs are not bred.


In summary, you can see that there is no easy way out of this mess we have created. Breeders are creating artificially small populations that result in heavily inbred dogs, but the rules are necessary to prevent welfare issues and other forms of bad breeding. Possible solutions all have their downsides, but are certainly necessary to prevent many breeds from becoming unsuitable for life! As a pet owner, you can do your bit by only purchasing dogs from breeders that have done extensive genetic and inbreeding testing, or even better, support local charities and adopt an unwanted dog!

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Further Reading