In recent years, the debate between purebred and mixed-breed dogs has intensified, even evolving into a form of "political correctness": it seems that only those who love and adopt mixed-breed dogs can be considered true "dog lovers." Many people use anecdotal evidence to argue that mixed-breed dogs are cuter, more obedient, healthier, and better suited for family life than purebred dogs. But is this truly the case? Scientific research provides a more objective perspective.

Health Issues in Purebred and Mixed-Breed Dogs: Insights from Scientific Studies

The University of California, Davis (UC Davis), home to the world’s top-ranked veterinary school, conducted a large-scale study analyzing medical records from its teaching animal hospital between 1995 and 2010. Researchers examined medical data from 90,000 purebred and mixed-breed dogs, focusing on 27,254 dogs diagnosed with 24 common genetic disorders. The study found that for 13 of these genetic diseases, there was no significant difference in prevalence between purebred and mixed-breed dogs. Among the remaining disorders, the incidence varied, but not all of them were more prevalent in purebred dogs.

This study was published on June 1, 2013, in the Journal of the American Veterinary Medical Association. Some experts have questioned the data sources, suggesting that as one of the nation’s top animal hospitals, UC Davis may receive more referral cases, and that owners of purebred dogs, who often have better financial resources, might be more willing to pay for expensive treatments. Nevertheless, the study still demonstrates that the theory of purebred dogs being universally more susceptible to genetic diseases applies only to certain specific conditions. In most cases, there is no significant health difference between purebred and mixed-breed dogs.

Another study led by Jonas Donner, the chief scientist at Genoscoper Laboratory in Helsinki, Finland, further investigated the genetic disease risks in mixed-breed dogs. By analyzing the genetic data of over 80,000 mixed-breed dogs, the research provided the first substantial evidence of genetic disorders in mixed-breed populations. The data showed that the most common genetic disease mutations occurred at roughly the same rate in both mixed-breed and purebred dogs. Furthermore, statistical data indicated that there was no significant difference in lifespan between the two groups, and in some cases, mixed-breed dogs had a shorter average lifespan.

These findings have encouraged purebred dog breeders to place greater emphasis on genetic screening to reduce the spread of hereditary diseases. However, are those who breed mixed-breed dogs making the same efforts to ensure their health?

The Fundamental Difference Between Purebred and Mixed-Breed Dogs: Genetic Stability

The core difference between purebred and mixed-breed dogs is not merely in appearance but in genetic stability. Through long-term natural and artificial selection, purebred dogs have been bred to ensure the stable transmission of desirable traits, allowing breeders to accurately predict their offspring’s physical characteristics and temperament, making management easier. However, this genetic stability also makes purebred dogs more susceptible to recessive mutations leading to genetic diseases. With advancements in genetic testing, many of these hereditary conditions can now be predicted and controlled.

In contrast, mixed-breed dogs exhibit greater genetic variability. Even if both parents have desirable traits, their offspring’s physical characteristics are unpredictable. If a mixed-breed dog inherits defective genes from one parent, repeated crossbreeding could further propagate these defects. In reality, people often focus on those "well-bred" mixed-breed dogs with appealing appearances while overlooking the many ordinary or even genetically flawed mixed-breed dogs. Breeders of mixed-breed dogs typically do not conduct genetic testing on their dogs and their offspring, instead relying on the assumption that "hybrid vigor" alone ensures good health. Some mixed-breed dogs with particularly attractive appearances may be sold at high prices under labels such as "designer breeds," while those that do not meet market preferences may face abandonment.

The Trend of Exotic Mixed Breeds: A Concern for the Pet Market

Mixed-breed dogs have an open gene pool, which can promote genetic diversity and be beneficial for the species in the long run. However, the idea of "letting nature take its course" is relative, as human intervention plays a significant role in this process.

Many mixed-breed dogs are just as adorable and cherished as purebred dogs, and for their owners, they are irreplaceable companions. Some mixed-breed dogs, after proper training, can serve as therapy dogs, rescue dogs, or even excel in sports competitions and film productions. However, a concerning trend is emerging—some breeders intentionally "design" dogs by crossbreeding two different purebred breeds to create novel appearances for profit. This practice differs significantly from responsible breeders who carefully introduce new genes to address specific breed-related health issues. Responsible breeders possess extensive knowledge and technical expertise to ensure their breeding efforts do not introduce new problems, and they conduct long-term monitoring to track their results.

With advancements in molecular biology, gene-editing technologies like CRISPR are being explored to address certain genetic conditions. However, many mixed-breed dog breeders do not consider such ethical and scientific issues; their primary goal is novelty and profit. These individuals often claim that mixed-breed dogs are universally stronger and healthier while discrediting purebred dogs and responsible breeders. Such misleading narratives contribute to misinformation and add to the chaos in the pet market.

Advocating for Responsible Breeding—Regardless of Breed

We advocate for responsible dog breeding—whether for purebred or mixed-breed dogs. Given the complexities of the pet market, for most people, choosing a well-bred and health-certified purebred dog is often a safer option. This choice ensures accountability not only for the dog but also for its future owners.

Of course, for those who already own a dog, these debates may not matter much. Genetics is important, but it is not the sole determinant of a dog’s health and happiness. We love our dogs for who they are and for the experiences we share with them. Our hope is that every dog is born out of love, finds the right owner, and enjoys a fulfilling life.

Both purebred and mixed-breed dogs have their own advantages and disadvantages, and it is simplistic to categorize one as "good" and the other as "bad." Whether choosing a purebred or a mixed-breed dog, the key lies in responsible breeding and ownership. We oppose indiscriminate breeding for novelty and profit and advocate for scientifically informed and compassionate breeding practices. Only by doing so can we foster a harmonious relationship between humans and pets and ensure that every dog enjoys a happy and healthy life.