The IHA Debate: Health, Hype and Hard Questions

Podcast due for release on the 28/6/26

The launch of the Innate Health Assessment (IHA) has sparked a passionate debate in the dog world.

Supporters see it as a practical, simple tool to help improve canine welfare by addressing extreme conformation. Critics have raised concerns about fairness, scientific validity, breed identity, and fears that it could ultimately threaten certain breeds.

To separate fact from fiction, Veterinary Voices UK sat down with Professor Dan O'Neill, veterinary epidemiologist at the Royal Veterinary College and one of the architects of the IHA, alongside Marisa Heath, Director of the All Party Parliamentary Group for Animal Welfare  (APGAW) and a long-standing animal welfare advocate.

Veterinary Voices UK opened up the discussion to everyone to pose their questions and concerns, and the discussion explored the most common questions raised by breeders, owners, veterinary professionals and the wider dog community.

What Is the IHA and Why Was It Created?

The Innate Health Assessment was developed as a simple-to-use tool to help people identify extreme conformational traits that may negatively affect a dog's welfare.

According to Marisa Heath, the tool emerged from years of frustration that despite growing awareness of breed-related health problems, meaningful progress remained slow.

"We wanted to create something simple enough for the public to understand and use," she explained. "This is fundamentally about helping people make informed choices."

Professor O'Neill added that the IHA focuses specifically on a dog's innate health—the physical foundations that allow a dog the capacity to live a normal, functional life.

Is the IHA Designed to Measure Overall Health and Welfare?

One of the most common misconceptions is that the IHA claims to assess a dog's overall health and welfare.

According to O'Neill, this is not its purpose.

Health and welfare encompass many factors, including (but not limited to):

• Nutrition

• Exercise

• Socialisation

• Veterinary care

• Training

• Living conditions

The IHA focuses on one specific area: whether a dog's physical structure limits its ability to perform normal canine functions.

"A dog may pass the IHA and still have poor welfare if it is neglected or badly cared for," O'Neill explained. "Equally, a dog may be loved and well cared for but still suffer because of physical conformational problems."

The IHA is intended as a foundation, not a complete welfare assessment.

Does the IHA Focus Too Much on Appearance?

Critics of the IHA have argued that the IHA places excessive emphasis on appearance rather than overall health.

The creators acknowledge that overall health is essential, and that is why the remit and scope of the IHA should not be taken out of context.

The IHA does not evaluate appearance for cosmetic reasons. Instead, it examines physical traits that directly affect function.

Examples include:

• Ability to breathe normally

• Ability to blink and protect the eyes

• Ability to wag a tail

• Ability to move comfortably

As Marisa Heath put it:

"If a dog can't breathe effectively, can't sleep properly, can't wag its tail or function normally, then you're already starting from a compromised position."

The argument is that behavioural wellbeing, emotional welfare and overall health are all essential and important, but also all are contingent on having a physically functional body in the first place.

Is Extreme Conformation Subjective?

A major concern raised is whether "extreme conformation" is simply a matter of personal opinion.

Professor O'Neill argues that before the IHA, decisions about what constituted an extreme dog were often subjective.

The IHA attempts to remove that subjectivity by introducing ten criteria with clearly defined pass/fail thresholds.

"The world before the IHA was subjective," he said. "The IHA introduces objective criteria and clear cut-off points."

Supporters argue that this consistency could help breeders, buyers and regulators work from the same framework rather than relying on personal interpretation.

What Does a Pass or Fail Actually Mean?

The IHA uses ten criteria. Dogs receive a pass or fail for each criterion, with an overall pass requiring at least eight successful scores currently.

Importantly, a failure does not automatically prevent breeding. That is a decision for the breeder within the law. 

The assessment simply provides information to help good breeders make good decisions.

A breeder, owner or buyer can then decide what action to take.

"The IHA is a tool, not a law," O'Neill emphasised. "It informs decisions; it does not make them."

Is the IHA a Step Towards Breed Bans?

Perhaps the most controversial claim surrounding the IHA has been the assertion from a small group online that was then widely shared in the media that the IHA could lead to 67 breeds being banned.

Both Marisa Heath and Dan O'Neill strongly reject this interpretation.

In fact, they argue the opposite.

The IHA was partly developed to help avoid breed bans by demonstrating that breeds can improve welfare outcomes through selective breeding rather than legislative prohibition.

"We're not trying to eliminate breeds," Heath said. "We're trying to ensure they remain sustainable and healthier."

Setting the Record Straight: The Truth About the IHA — Innate Health Assessment 

How Were the IHA Criteria Chosen?

Transparency has been a key issue for critics, who do not believe there is a scientific basis for the criteria chosen.

O'Neill explained that the assessment evolved from more than a decade of veterinary research into inherited disorders and breed-related health problems.

Initially, around 25 potential criteria were considered.

These were eventually reduced to ten based on two principles:

1. Objectivity

The trait had to be easy to identify consistently.

2. Broad Health and Welfare Relevance

The trait needed to apply across many breeds rather than targeting specific breeds.

Some traits were excluded because they were:

• Difficult to score reliably

• Highly breed-specific

• Less suitable for a public-facing assessment tool

The goal was to create a system that was practical, understandable and widely applicable.

How Does the IHA Define Extreme Conformation?

Professor O'Neill pointed to an internationally published definition used by the International Collaborative on Extreme Conformations in Dogs.

Extreme conformation is defined as:

Extreme conformation describes a physical appearance that has been so significantly altered by humankind away from the ancestral natural canine appearance that affected animals  commonly suffer from poor health and welfare, with negative impacts on their quality and quantity of life.

The emphasis is not on aesthetics but on conformational features that can have measurable negative impacts on quality of life.

Why Was Merle Included?

One of the most debated aspects of the Innate Health Assessment (IHA) since its launch has been its treatment of dogs displaying merle colouration. While some welcomed the original restriction as a precautionary welfare measure, others argued that advances in genetic testing meant responsible merle breeding could be managed safely without a blanket restriction.These latter arguments have now been taken into account within the IHA, with some new changes on genetic testing for merle soon to be enacted for the IHA.

Following extensive discussions with stakeholders including the breeding community and the Royal Kennel Club, the IHA has now announced a new conditional pass pathway to breeding for some merle-coloured dogs. The update reflects scientific understanding of merle genetics, but it has also prompted fresh discussions within the breeding community about how the new criterion will be applied and its restrictions.

The proposed change is:

Criterion 1: Merle colouration

Dogs displaying visible merle colouration may now receive a conditional pass for breeding purposes, provided the breeder agrees to carry out genetic testing for merle-associated variants (the specifics of this testing will be released soon). Where testing confirms the presence of genetic merle variants, the breeder must give a written commitment that the dog will only be mated with a partner who has been confirmed through genetic testing not to carry merle-associated variants.

This replaces the previous position under Criterion 1. All other criteria remain unchanged.

Background to Merle Genetics 

Merle is a coat pattern caused by a mutation in the SILV (PMEL) gene.

Researchers found that merle inheritance was more complex than originally thought.

Dogs with similar genetic test results did not always display the same coat patterns, and unexpected health issues sometimes occurred in offspring.

In addition to the non-merle variant m, further research identified multiple merle variants—including Mc, Mc+, Ma, Ma+, M, and Mh—each associated with different coat colour expressions and levels of health risk.

Researchers also discovered that merle mosaicism, where a dog carries more than one merle variant in different cells in the body, is relatively common. Importantly, even minor merle variants can be passed on to offspring, making comprehensive genetic testing essential for accurate breeding decisions if the breeder still plans to breed for merle colouration and wishes to reduce the risk of ocular and hearing problems.

These findings have significantly improved understanding of merle genetics and support the use of advanced merle testing to help breeders select compatible mating pairs, reduce health risks, and produce healthier puppies if they still decide to breed for merle colouration.

As some merle-merle matings are associated with health risks, it is important that breeders are consistent and avoid pairing genetically incompatible individuals, which can lead to offspring with a genotype associated with serious health problems.  

Researchers have identified multiple merle variants, ranging from cryptic merle (which may show little or no visible merle pattern) to standard and harlequin merle forms.

The IHA's Updated Position 

On the date of publication of this blog (28/6/26), following extensive discussions with stakeholders, plans have been put in place to update the merle criterion on the IHA.

This update will introduce a conditional pass pathway for a subset of visibly merle dogs. A conditional pass allows these dogs to proceed to breeding assessment provided the user confirms that appropriate genetic testing will be (or has been) carried out, and that, dependent on these genetic results, that any proposed mating partner is confirmed to lead to low genetic risk of adverse merle-related health outcomes for the puppies.

This approach reflects current scientific understanding of merle genetics and the IHA team are very grateful to Dr Joanna Ilska and Dr Alison Skipper of the RKC for their substantial advice and inputs here. 

 "We've always said we would review and adapt the IHA where appropriate," Heath explained.

IHA updates its merle criterion — Innate Health Assessment 

Criterion 1: Merle colouration

Dogs displaying visible merle colouration may now receive a conditional pass for breeding purposes, provided the breeder agrees to carry out genetic testing for merle-associated variants (the specifics of this testing will be released soon). Where testing confirms the presence of merle genetics, the breeder must also give a written commitment that the dog will only be mated with a partner who has been confirmed through genetic testing not to carry merle-associated variants.

The article details that the updated criterion provides responsible merle breeders with a clear route forward while maintaining the essential protections in place. Further details of the specific testing requirements needed to satisfy the conditions for receiving a conditional pass under the merle criterion will be released in due course. 

Although the change reflects the creators' willingness to modify the tool when presented with evidence and practical solutions, there are still potential concerns raised by breeders/ advocates of known merle pattern breeds for the updated criterion because the new amendment does not currently appear to account for all health tested merle matings or dogs that fall under the ‘cryptic merle’ category.

The IHA team have said that this criterion is going to be added officially following the release of further information; a document showing wider information on merle genetics, how to take a DNA sample and a list of DNA testing laboratories will also be provided on the IHA website.  They are reminding people that the current aim is 8 out of 10 criteria for a pass and that this is not a mandatory tool, so pragmatism can be used where evidence-based and informed breeding choices are made.

Could the IHA Reduce Genetic Diversity?

Another common concern is that selecting against certain traits could shrink breeding populations.

O'Neill highlighted that all selective breeding affects genetic diversity to some degree and that this loss of genetic diversity is greater and faster in closed breeding populations.

However, he argued that current breeding practices which focus on extreme traits already exclude many genetically valuable dogs because they are too moderate to  fit current breeding goals.

For example, tailed French Bulldogs may currently be excluded from breeding programmes because they are too moderate, despite potentially offering welfare benefits as well as additional genetic diversity.

In this context, the IHA may actually encourage a broader breeding pool by promoting healthier variations within breeds.

The discussion also highlighted increasing acceptance of:

• Outcrossing between lines and breed subtypes

• International genetic exchange

• Greater genetic diversity strategies

• Outcrossing between breeds

as part of future breed sustainability.

Are We Trying to Turn Every Dog Into a Street Dog?

Some critics have claimed the IHA seeks to push all dogs toward a generic "street dog" appearance.

The creators describe this as misinformation and absurd.

They believe the goal is not to eliminate breed diversity but to preserve it by reducing harmful extremes.

"The IHA is celebrating dogs," Heath said. "It's about helping all breeds achieve the best health and welfare possible."

O'Neill pointed out that dog diversity is actually increasing, with hundreds of recognised breeds and growing numbers of designer crossbreeds being added every year.

The aim of the IHA, he argues, is not uniformity but moderation and diversity.

Who Is Responsible for Improving Dog Welfare?

The final theme centred on accountability.

Both guests rejected the idea that any single group is solely responsible, despite online conversations regularly accrediting blame to each other. 

Rather than blaming:

• Breeders

• Owners

• The show world

• Veterinary professionals

• Charities

• Academics

They argued that everyone has a role to play.

Marsia Heath noted that market demand drives much of modern breeding.

If buyers prioritise acquiring healthier dogs, breeding practices will follow.

Dan O'Neill emphasised that blame creates division, whereas accountability encourages progress.

"The IHA isn't about saying who is good and who is bad," he said. "It's about providing a tool that helps everyone make better decisions."

Looking Forward

The creators repeatedly stressed that the IHA is not a finished product.

It is designed to evolve as new evidence emerges and as discussions continue with breeders, welfare organisations, veterinary bodies and breed representatives.

The recent merle update is presented as evidence of that process already taking place.

Ultimately, both Marisa Heath and Dan O'Neill argue that the conversation should move away from fear and misinformation and focus instead on a shared goal: improving the welfare of dogs while preserving the breeds people love.

As O'Neill concluded:

"The IHA is just a tool. The real change happens between our ears—individually and collectively."