Learn Which Dog Breed Has the Most Genetic Mutations

Genetic mutations are capable of promoting the presence of dangerous congenital diseases, such as mitral valve prolapse or neurological disorders.
Learn Which Dog Breed Has the Most Genetic Mutations
Cesar Paul Gonzalez Gonzalez

Written and verified by the biologist Cesar Paul Gonzalez Gonzalez.

Last update: 22 December, 2022

Dogs are one of the most popular pets of all Apart from the fact that they’re not usually too difficult to look after, there are so many different breeds that can be adapted to almost any person. However, the huge demand for some types of dogs has led to the appearance of several genetic mutations and health problems, which are typical of the breed.

Generally, certain protocols are followed during dog breeding to avoid or reduce inbreeding (reproduction between relatives). This helps to reduce genetic problems caused by artificial selection, but not all breeders follow these rules. Over time, every dog generates genetic mutations, but there’s one breed that has more than others. Discover it below.

What are mutations?

Mutations are an alteration in the DNA sequence that may or may not cause a change in the characteristics of the species. These modifications occur naturally and are random, although certain conditions also favor their presence.

The changes that a mutation can generate range from a metabolic affectation to body deformity, depending on which genes are affected. In most cases, the affectations are known as congenital diseases and are very detrimental to the health of the species.

Usually, one mutation isn’t enough to cause changes in the appearance of the organism, but an accumulation of mutations is needed. However, mating between close relatives increases the likelihood that these mutations will accumulate. This is the reason why congenital diseases occur in this type of mating.

Why do mutations appear in dogs?

In the case of dogs, in order to maintain the “purity” of the breeds, breeders usually choose to mate close relatives. Over time, the breeding process caused mutations to accumulate and led to the presence of congenital diseases.

Inbreeding was also a process that helped to establish the representative characteristics of dog breeds. In order to maintain the cutest or most showy traits, it was preferred to mate dogs with their close relatives (artificial selection). This is what created the great diversity of breeds, but at the same time it harmed their long-term health.

This is why dogs with “pedigree” tend to have more health problems when they grow up. Of course, their susceptibility to congenital diseases varies according to the history of the breed, but those in most demand are the most affected.

A dog and its owner.

Does the process of breeding affect dog health?

In 2008, a group of scientists from Uppsala University, Sweden, conducted an analysis to corroborate that dogs had a greater number of harmful mutations. To do this, they compared the dog genome with the genome of the gray wolf (Canis lupus), which is their closest ancestor.

At the end of the research, they realized that dogs had many more deleterious mutations than their wild ancestor. This means that the breeding process affects the dogs’ health quite a bit, as well as increasing the number of mutations in their genome.

What dog breed of dog has the most mutations?

As you can guess, the selective breeding that “purebred” dogs go through is too damaging. However, there’s one breed of dog that has been greatly affected by genetic mutations. This is none other than the Cavalier King Charles Spaniel, which also has a long list of congenital diseases.

In 2021, an article published by the scientific journal Plos Genetics revealed that the Cavalier King Charles Spaniel had about 10% more mutations in its genome than other popular breeds. This is understandable, since they have suffered from selective breeding since the 16th century.

In fact, in 2007 this breed was ranked as the sixth most popular worldwide, but in 2009 it climbed to fourth place. Therefore, its lineage is still under great pressure, as the demand hasn’t ceased for too long.

Cavalier King Charles Spaniel.

A Cavalier King Charles Spaniel’s health?

Despite being a charismatic dog breed, it suffers too much from genetic mutations. In fact, about 31% of the specimens of this breed suffer from heart disease. Mainly, the dogs suffer from mitral valve prolapse, a congenital and dangerous condition specific to the breed.

However, there are also many other common diseases in these dogs. Among the most common are the following:

  • Heart murmurs
  • Periodontal problems
  • Conjunctivitis
  • Gastrointestinal pathologies
  • Anal sac infection
  • Dermatological problems
  • Syringomyelia (alteration of the nervous system)
  • Chiari type malformation

Although dogs are excellent household companions and very loyal friends, the reality is that the breeding process affects them drastically. To prevent this from happening, prioritize adopting your pet from certified breeders, as these places guarantee the breed’s health. Although it may be a little more expensive, it’s worth it in order to keep such beautiful animals healthy.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Axelsson, E., Ljungvall, I., Bhoumik, P., Conn, L. B., Muren, E., Ohlsson, Å., … & Lindblad-Toh, K. (2022). Correction: The genetic consequences of dog breed formation—Accumulation of deleterious genetic variation and fixation of mutations associated with myxomatous mitral valve disease in cavalier King Charles spaniels. PLoS Genetics, 18(1), e1010039.
  • Cruz, F., Vilà, C., & Webster, M. T. (2008). The legacy of domestication: accumulation of deleterious mutations in the dog genome. Molecular biology and evolution, 25(11), 2331-2336.
  • Hillbertz, N. S., & Andersson, G. (2006). Autosomal dominant mutation causing the dorsal ridge predisposes for dermoid sinus in Rhodesian ridgeback dogs. Journal of Small Animal Practice, 47(4), 184-188.
  • Rusbridge, C. (2005). Neurological diseases of the Cavalier King Charles spaniel. Journal of Small Animal Practice, 46(6), 265-272.
  • Summers, J. F., O’Neill, D. G., Church, D. B., Thomson, P. C., McGreevy, P. D., & Brodbelt, D. C. (2015). Prevalence of disorders recorded in Cavalier King Charles Spaniels attending primary-care veterinary practices in England. Canine Genetics and Epidemiology, 2(1), 1-15.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.