Inbreeding in purebred dogs and its effect on reducing longevity and increasing morbidity is discussed on a regular basis. Stopping breeding altogether is an often-cited remedy. Another is the abandonment of separate breeds in favour of one large gene pool. Would either of these solutions work in practice?

This article by Katariina Mäki, PhD, is a translation of a Finnish article 'Lääke rotukoirien sukusiittoisuuteen: yhdistetään kaikki rodut?'

Popular solutions

More and more information about the effects of inbreeding on longevity and morbidity is accumulating every year. A recent study comparing the lifespans of purebred, multi-breed and cross-bred dogs showed once again that diversity brings vitality: Multi-breeds lived the longest and crossbreeds the second longest.

A popular suggestion to cure inbreeding and health problems is to stop breeding.

Abandoning separate breeds is another commonly suggested remedy. If all breeds were bred together, freely crossed, the gene pool would be as large as all breeds combined and the situation would improve for good.

Would that really be the case?

Would these methods be feasible in practice? Would they work?

The answer is no.

And why? Let's have a look.

Remedy 1 - Stop breeding dogs.

The keeping of dogs as pets means that dogs are also being bred.

Whenever we decide which individuals will parent the next generation, we are selectively breeding whether we like it or not. These decisions have an impact on which genes are retained in the dog population and which ones are culled.

It goes without saying that selective breeding must maintain and promote the health of the dogs. This is not always the case today.

But stopping breeding is not the answer.

Remedy 2 - Combine all breeds into one large population.

This would result in one large gene pool.

Would it work?

In the very short term, yes.

In the long term, no.

In the long run, the gene pool would gradually become smaller because there would always be popular sires that would be used more than others for breeding. Gradually the genes of these dogs - including the harmful ones - would become more widespread, and the genes of those culled from breeding would disappear.

A good example of how large population size does not necessarily mean large genetic variation is the Holstein, the most common dairy breed in the world. There are a few million Holstein cows in the world, but the number of bulls used for breeding is so small that genetically the population consists of only about 50 animals.

If all dogs were one big breed, where would new genes come from when the need arose?

How would combining the breeds happen in practice?

Would all the breed enthusiasts in the world agree and act? Even those whose centuries-old national breeds would disappear? Would we Finns be ready to give up our national dog, the Finnish Spitz?

No, no. This will never happen.

Combining breeds would not necessarily improve the welfare of either dogs or people.

Mixing all breeds into one would reduce the predictability of personality traits in dogs.

It is difficult to find the right puppy for the right home if there is no way of predicting the puppy's personality. Energetic dogs that are difficult to control could end up in homes where they do not get enough exercise, brainwork, and stimulation. This could lead to more "problem dogs".

Mixing all breeds into one would mean giving up the long-established working characteristics that have been bred into the breeds and form the basis of breed-specific behaviour.

The use of many working dogs, including two-breed crosses, to assist people is based on the working characteristics and typical personality traits of the breeds. The selection and availability of dogs that can be trained to assist people would be more difficult if there were no breeds and predictability.

But the idea behind the Remedy 2 makes sense.

There are hundreds of different dog breeds in the world. So many, in fact, that not nearly all of them can be found in one country, such as Finland.

Many breeds have very small populations. Some breeds have been further divided into smaller populations, ie varieties. This usually means that the effective size is small, which eventually leads to increased relatedness and inbreeding.

Fortunately, many varieties can be crossed with each other. In some breeds it is also possible to introduce unregistered landrace dogs into the breed, and thus broaden the gene pool.

However, a breed can have a small gene pool even if it is large in number and not split into separate varieties. The breed can also accumulate harmful mutations and traits to such an extent that it is not possible to improve the situation by breeding within the breed. In such cases, new genes would have to be obtained from outside the breed.

On the other hand, genes cannot be sourced from outside the breed if the registries are closed to prevent gene flow. This straitjacket was put on breeds in the late 19th century when purebreds became a virtue and crossbreeds a curse, describing inferior beings.

Fortunately, at the beginning of this millennium, the need for crossbreeding began to be more widely recognised. However, it was still a lot of work and not always possible to make licensed crosses under the auspices of the kennel clubs. In the light of all this, the idea of combining the breeds is a very logical one.

However, the same result can also be achieved by broadening the current, narrow concept of what constitutes a breed. This issue was discussed at the 2019 International Dog Health Workshop, Windsor, UK. As a result of the discussions, there was a recommendation for the opening of breed registries in a controlled way.

The next workshop will be held in Finland on 13-16 June 2024. This issue will no doubt be on the agenda again.

Finnish Kennel Club's new cross-breeding register enables larger gene pools

There is already light at the end of the tunnel for crossbreeding: In June 2023, the Finnish Kennel Club (FKC) announced its decision to create a separate register for crossbreeds. This was long-awaited good news.

At the same time, the FKC announced that it had approved crossbreeding projects for Cavalier King Charles Spaniels and French Bulldogs. The Swedish Kennel Club has also approved a crossbreeding project for Cavaliers. 

Not everyone has reacted positively to the news from Finland and Sweden about crossbreeding. It is not understood that even a breed with large numbers can be genetically very small. And if harmful genes are fixed in the breed, no normal genes can be found to replace them, except from other breeds. You have to crossbreed if you want to go on.

The good news is that the new crossbreeding registry is separate from the FCI registry. This will allow crossbreeding in breeds that are not crossbred elsewhere. Crossbred dogs will only enter breeding if they are approved based on their health and other characteristics.

This is how the new system will work:

• The first crossbred generation (F1) will always be entered into the crossbreed register.
• In subsequent generations (F2-F4), dogs can be transferred to the FKC's appendix register (ER) on request. The ER register is an FCI register for dogs that do not meet all the requirements of the pedigree register.
• Transfer to the appendix register means that these dogs can also be used for breeding to improve the breed.
• From generation F5 onward, the offspring will be fully recognised as purebred members of the breed and registered normally.

The purpose of the new register is therefore to allow more crossbreeding and to create a pathway for new genes into the gene pool of the breed.

Let's hope that this new opportunity will be used widely and with a low threshold - preferably long before a breed reaches a dead end!

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Further information

4th International Dog Health Workshop – The Concept of Breed and how it influences health and welfare of dogs.

Mata & Mata 2023. Investigating the relationship between inbreeding and life expectancy in dogs: mongrels live longer than pure breeds.