The Debate on Responsible Dog Breeding

When Veterinary Experts Disagree – What Does This Mean for Breeders?

"Science is not a collection of ready-made truths but an ongoing process. It asks questions, searches for answers, tests hypotheses, and continually revises its own conclusions. That is precisely why it cannot provide simple recipes." Dr. Marie NitzschnerScientific Director, KynoLogisch gGmbH

Most readers will have followed the intense debate surrounding dog breeding and the allegation of so-called "torture breeding" (Qualzucht) in Germany. As the interpretation of Section 11b of the German Animal Welfare Act continues to evolve, an increasingly important question arises:

How should genetic findings be evaluated under animal welfare law in the future?

Ultimately, this interpretation rests with the competent veterinary authorities responsible for enforcing the legislation. It is precisely at this intersection of science and law that a debate has emerged among veterinary experts—a debate that is likely to have far-reaching consequences for dog breeding.

For me, this issue is personal.

One of my stud dogs tested heterozygous positive for CDDY.

CDDY (Chondrodystrophy) is a genetic variant that affects cartilage and bone development and, in certain breeds, is associated with an increased risk of intervertebral disc disease (IVDD), most notably in the Dachshund. However, its clinical significance depends on the breed and cannot be inferred from a DNA test alone.

My dog shows no clinical signs whatsoever. He is an athletic Dansk–Svensk Gårdshund, measuring approximately 38/39 cm at the withers. Orthopaedic examination is entirely unremarkable. He has no neurological deficits, no clinical evidence of spinal disease, and radiographic examination reveals no signs of intervertebral disc pathology.

Suddenly, I found myself asking a question that many conscientious breeders have probably asked themselves:

What does a genetic test result actually tell us?

Does a positive DNA test automatically justify excluding a dog from breeding?

Or should science provide more than simply identifying genetic variants?

I was not looking for opinions.

I wanted to understand.

So I began reading scientific publications.

I worked my way through breeding strategies, peer-reviewed studies, position papers and official guidelines. I was especially grateful that Professor Dannika Bannasch of the University of California, Davis, personally took the time to answer several of my questions.

The deeper I immersed myself in the literature, the more obvious the complexity of the subject became.

Scientific evidence, legal interpretation, breeding strategies and political objectives are closely intertwined—and experts reviewing the very same data often reach different conclusions.

Above all, however, one thing became increasingly clear to me:

This discussion is no longer merely about CDDY.

It is about how responsible pedigree dog breeding will be defined in the future.

CDDY – More Than a DNA Test

CDDY (Chondrodystrophy) is a genetic variant that, particularly in strongly chondrodystrophic breeds such as the Dachshund, has been associated with an increased risk of intervertebral disc disease (IVDD).

For the Dansk–Svensk Gårdshund, however, the currently available scientific evidence paints a considerably more nuanced picture.

The CDDY allele occurs relatively frequently within the breed population. At the same time, the Swedish Kennel Club's Breed-Specific Breeding Strategy (RAS) explicitly states that insurance data collected to date do not indicate an increased incidence of IVDD in the breed.

Even the widely cited research conducted by Professor Dannika Bannasch and her colleagues demonstrates how carefully scientific findings must be interpreted.

In one study, six Dansk–Svensk Gårdshunds were examined: five clinically healthy dogs and one dog diagnosed with IVDD. Both the affected dog and one clinically healthy dog carried a single copy of the CDDY allele.

Based on these findings alone, no causal relationship between CDDY and disease can be established for this breed.

For precisely this reason, the Swedish Kennel Club does not recommend the general exclusion of CDDY carriers from breeding.

Instead, the recommended strategy is to mate carriers with genetically clear partners while testing the offspring. The objective is to gradually reduce the frequency of the allele over time without unnecessarily sacrificing valuable genetic diversity.

This Is Where the Real Debate Begins in Germany

As I continued reading, I came across two publications that could hardly be more different.

On one side stands the Task Force Healthy Dog Breeding, an interdisciplinary group of geneticists, veterinarians and scientists from various fields.

Their objective is to translate scientific knowledge into practical guidance for breeders and veterinary professionals.

I find this approach convincing.

Science should not provide simplistic answers.

Its purpose is to support well-informed decision-making—particularly where no simple answers exist.

The central message of the Task Force guideline, "CDDY/CDPA – Responsibly Considering Genetic Variants in Dog Breeding," is therefore not the individual gene.

Its focus is the population. The key principle is straightforward:

Healthy populations are not created by excluding as many genetic carriers as possible from breeding. Healthy populations are created by managing genetic risks responsibly while preserving genetic diversity.

This population-genetic approach has formed the cornerstone of modern conservation breeding for many years. Yet it is precisely here that the controversy begins.

The Core of the Conflict in Germany

This population-based approach, however, is challenged by an Open Letter addressed to the German Federal Chamber of Veterinary Surgeons (Bundestierärztekammer), initiated by Professor Achim Gruber and supported by numerous board-certified veterinary specialists as well as representatives of the public veterinary authorities. ( see references)

The authors explicitly caution against adopting the recommendations of the Task Force as a model for other dog breeds.

In their view, a population-genetic approach is not an appropriate foundation for future breeding recommendations and could create substantial difficulties in the practical enforcement of Section 11b of the German Animal Welfare Act.

This illustrates an important point.

The debate is not about whether dogs should be healthy.

Both sides share that objective.

The difference lies in how that objective should be achieved.

The Task Force approaches canine health from the perspective of population genetics.

The Open Letter evaluates the same scientific evidence primarily through the lens of animal welfare legislation and regulatory enforcement.

To me, this is the true heart of the debate.

It is no longer simply about CDDY.

It is about the future role that scientifically sound population genetics will play in responsible pedigree dog breeding.

Why This Development Gives Me Pause

Hardly any dog breed is entirely free of genetic risk factors.

Nearly every population carries recessive mutations or genetic variants that have been associated with particular diseases. Many of these variants never result in clinical disease.

Others exhibit only low penetrance, meaning that only a proportion of genetically affected dogs will ever develop clinical signs.

Still others—such as CDDY—have markedly different clinical significance depending on the breed.

This is precisely why population genetics is so important.

It does not evaluate genes in isolation.

It evaluates the population as a whole.

Every breeding decision inevitably alters the genetic composition of a breed.

While researching this subject, I was particularly interested in an article by Dr. Heike Diekmann, published by the Society for the Promotion of Cynological Research (Gesellschaft zur Förderung Kynologischer Forschung, GKF).

Using the Nederlandse Kooikerhondje as an example—a breed with a comparatively small gene pool requiring particularly careful breeding management—she illustrates a fundamental principle of population genetics through a simple thought experiment.

She introduces two hypothetical genes.

The first gene influences the activity of a liver enzyme.

The second carries a recessive mutation capable of causing an inherited disease.

She then poses a seemingly straightforward question:

Why not simply exclude every carrier of the disease-causing mutation from breeding?

The answer is surprisingly instructive.

In her example, the disease-associated allele happens to be inherited together with the most advantageous variants of the liver-enzyme gene.

Consequently, eliminating every carrier would remove not only the disease mutation but also the genetically most valuable versions of the liver-enzyme gene.

As a result, the proportion of homozygous gene combinations increases, genetic diversity declines, and the population loses beneficial characteristics whose importance had not even been recognized beforehand.

This is the central message of the example.

Genes never act in isolation.

Removing a single allele from a population inevitably changes many other genetic characteristics at the same time.

Population genetics therefore does not mean accepting inherited disease.

Rather, it means reducing disease risk while preserving the genetic foundation required for the long-term health and viability of an entire population.

Conclusions

Veterinary experts disagree. Legislative restrictions are being discussed. Personally, I find myself favouring a considerably more liberal—albeit inevitably slower—approach. I have never believed that prohibitions alone provide sustainable solutions.

Regulating breeding without simultaneously addressing the purchase and importation of dogs merely shifts the problem elsewhere.

The Netherlands provides an instructive example. Since 2019, strict breeding regulations have applied to brachycephalic breeds such as Pugs, French Bulldogs and Shih Tzus. Yet consumer demand remained unchanged. Many prospective owners simply purchased their dogs abroad. Faced with this unintended consequence, the Dutch Minister of Agriculture even proposed extending the legislation to restrict the ownership of these dogs. The original breeding regulations alone had failed to reduce demand, requiring further legislative intervention.

This illustrates an important principle:

As long as demand remains unchanged, production will simply relocate.

For that reason, I believe the discussion should extend far beyond breeding regulations alone.

We need greater transparency for prospective puppy buyers.

We need better public education about inherited disease and responsible breeding.

Online advertising and sales platforms should assume greater responsibility for the information they provide.

The long-term financial consequences of hereditary disease should be made more visible to prospective owners.

Breeders themselves should receive comprehensive education. Responsible breeding requires expertise in genetics, animal health, behaviour, reproduction, population management and ethics. In my view, this level of responsibility deserves structured education comparable to professional training.

At the same time, we should not overlook the most influential stakeholder of all:

The buyer.

May I ask you, the reader, a simple question?

How much attention do you pay to breeding before purchasing a puppy?

Dog breeding is a complex system involving breeders, veterinarians, kennel clubs, legislators, researchers and animal welfare organisations.

Ultimately, however, it is shaped by one decisive force:

Consumer demand.

What people choose to buy is what breeders will continue to produce.

For this reason, the most sustainable long-term improvement is likely to come from increasing public awareness.

Potential owners should understand why they should avoid purchasing dogs from breeds characterised by extreme inherited traits or genetic disorders that are highly likely to compromise health and welfare. Every purchasing decision influences the future of dog breeding.

Consumers therefore play a far greater role in this debate than they may realise.

As for my own CDDY-positive stud dog, I intend to follow the principles of modern population genetics.

My breeding decisions will continue to be guided by scientific evidence, careful risk assessment and the preservation of genetic diversity, rather than by the presence or absence of a single genetic variant.

Every day I enjoy the company of healthy, active and well-balanced dogs that enrich my life. I am still a relatively young breeder, and my oldest offspring are now only nine years of age. To date, I have not encountered any serious inherited disease within my breeding programme. My dogs are living healthy lives with devoted owners. For me, this remains the most meaningful measure of responsible breeding.

It is with that encouraging observation that I conclude this article.

Thank you for reading.

References

Open Letter of the Veterinary Profession. (2026). How Much Animal Suffering Is Acceptable to Preserve Breed Characteristics? Faculty of Veterinary Medicine, Freie Universität Berlin, 1 July 2026.

This position paper argues that breeding practices should prioritize animal health over breed-specific conformation traits where these are associated with hereditary disease. Referring to the revised German Animal Welfare Act and current scientific literature, the authors advocate a stricter interpretation of breeding regulations and recommend limiting the use of dogs carrying genetic variants associated with inherited disorders, including the FGF4 retrogene (CDDY) where considered relevant. The document represents a professional policy statement rather than original peer-reviewed research.

Healthy Dog Breeding Task Force. (2026). Chondrodysplasia, Chondrodystrophy and Hereditary Increased Risk of Intervertebral Disc Disease. Healthy Dog Breeding (TGH), Guideline, 15 April 2026.

This evidence-based guideline reviews the current scientific knowledge on the FGF4 retrogenes responsible for chondrodysplasia (CDPA, CFA18) and chondrodystrophy (CDDY, CFA12). It concludes that CDPA is not associated with an increased risk of intervertebral disc disease (IVDD), whereas CDDY represents a genetic risk factor for IVDD in some, but not all, dog breeds. The guideline emphasizes that IVDD is a multifactorial disease influenced by additional genetic and environmental factors, and recommends breed-specific breeding strategies, radiographic screening where appropriate, preservation of genetic diversity, and avoidance of excluding dogs from breeding solely on the basis of their CDDY genotype. It further calls for prospective breed-specific studies to better quantify the clinical significance of the CDDY allele. 

Brown, E.A., Dickinson, P.J., Mansour, T., Sturges, B.K., Aguilar, M., Young, A.E., Korff, C., Lind, J., Ettinger, C.L., Varon, S., Pollard, R.E., Penderis, J., Garosi, L., Shelton, G.D., Rusbridge, C., Vernau, K.M., Drögemüller, M., Drögemüller, C., Leeb, T., Bannasch, D.L. (2017). FGF4 retrogene on CFA12 is responsible for chondrodystrophy and intervertebral disc disease in dogs. Proceedings of the National Academy of Sciences of the United States of America (PNAS), 114(43), 11476–11481. https://doi.org/10.1073/pnas.1709082114

This landmark study identified the FGF4 retrogene insertion on canine chromosome 12 (CFA12) as the genetic variant responsible for chondrodystrophy (CDDY) and strongly associated with intervertebral disc disease (IVDD), reporting an odds ratio of 51.23 for IVDD.

Batcher, K., Dickinson, P.J., Giuffrida, M.A., Sturges, B.K., Vernau, K.M., Knipe, M.F., Rasouliha, S.H., Drögemüller, C., Leeb, T., Maciejczyk, K., Jenkins, C.A., Mellersh, C.S., Bannasch, D.L. (2019). Phenotypic Effects of FGF4 Retrogenes on Intervertebral Disc Disease in Dogs. Genes, 10(6), 435. https://doi.org/10.3390/genes10060435

This study investigated the phenotypic effects and breed distribution of the CFA12 FGF4 retrogene, reporting CDDY allele frequencies ranging from 0.02 to 1.00 among different dog breeds.

Murphy, B.G., Dickinson, P.J., Marcellin-Little, D.J., Batcher, K., Raverty, S., Bannasch, D.L. (2019). Pathologic Features of the Intervertebral Disc in Young Nova Scotia Duck Tolling Retrievers Confirm a Chondrodystrophic Degenerative Phenotype Associated with FGF4 Retrogene Genotype. Veterinary Pathology, 56(6), 886–894. https://doi.org/10.1177/0300985819852128

This pathological study confirmed premature intervertebral disc degeneration associated with the CFA12 FGF4 retrogene genotype in young Nova Scotia Duck Tolling Retrievers.

Bannasch, D.L., Batcher, K., Leuthard, F., Bannasch, M., Hug, P., Marcellin-Little, D.J., Dickinson, P.J., Drögemüller, M., Drögemüller, C., Leeb, T. (2022). The Effects of FGF4 Retrogenes on Canine Morphology. Genes, 13(2), 325. https://doi.org/10.3390/genes13020325

This study distinguished the effects of the CFA12 (CDDY) and CFA18 (CDPA) FGF4 retrogenes. One copy of the CFA12 retrogene reduced limb length by approximately 6%, while two copies resulted in an average reduction of about 10%. Unlike the CFA18 retrogene, the CFA12 variant is additionally associated with susceptibility to intervertebral disc disease.

Olby, N.J., Batcher, K., Dickinson, P.J., Bannasch, D.L., et al. (2020). Current Understanding of the Genetics of Intervertebral Disc Degeneration. Frontiers in Veterinary Science, 7, 431. https://doi.org/10.3389/fvets.2020.00431

This review summarizes the current understanding of the genetics of canine intervertebral disc degeneration. It emphasizes that prospective longitudinal studies are still needed to accurately quantify the clinical IVDD risk associated with the CFA12 FGF4 retrogene, particularly in breeds with very high allele frequencies such as Dachshunds, Beagles, and French Bulldogs.