British equine studbook takes steps to stamp out ‘awful disease’
PSSM1 testing for foals was brought in this year as a requirement for studbook inclusion, with immediate effect
The British Appaloosa Society (BApS) is introducing mandatory PSSM1 testing for its main studbook, a step that will “improve the long-term health and welfare of the breed”.
The decision to introduce the testing with immediate effect was made at the society’s AGM in May. All foals registered with the BApS main studbook must either test negative for PSSM1 – polysaccharide storage myopathy type one – or be proven negative by parentage.
“This landmark decision reflects the society’s long-term commitment to eradicating PSSM1 from the British appaloosa population,” a society spokesperson said.
PSSM1 is a genetic muscle disorder, caused by a gene mutation that causes a horse’s muscles to produce and store abnormal levels of glycogen, the form of sugar stored in muscle. Signs can be mild to severe and include “tying up”, undiagnosable lameness and muscle soreness. It is commonly associated with appaloosas, although it has been identified in more than 20 breeds and the society has been battling it for years.
PSSM1 testing for stallions first
Since 2010, only stallions who test negative for PSSM1 have been accepted for licensing.
“The introduction of mandatory testing for main studbook foals is the next logical step in this successful programme, ensuring future generations of British appaloosas are protected from this inherited condition,” said the society spokesperson.
Society registrar and chair Paula Moore noted that the mutation is dominant, so horses only need one copy of it to have the condition, unlike a recessive trait that needs a copy from each parent to be expressed.
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“PSSM1 is a debilitating condition that can be inherited from either parent,” she told H&H.
“We sent letters to owners of aged stallions beyond 2011, asking them to do the right thing and test, and some did, some didn’t. We’ve asked mare owners to test breeding stock; a lot have complied and we’ve got a good relationship with breeders. But there are still people who choose to ignore it or pretend it doesn’t happen.
“We’re still getting animals testing positive for PSSM1. So we decided as it’s our 50th anniversary this year, it’s time we had a proper serious look at leading the way and future-proofing the breed.”
Ms Moore said she proposed the mandatory testing at the AGM and the vote was unanimous.
“It’s easy to do; test the foal when the vet comes to do the passport,” she said. “It has to be done by a vet as we need the integrity.”
“Such an awful disease”
Ms Moore added that as all BApS-licensed stallions are clear of PSSM1, the other option is for owners to test their mares. If both parents are clear, their foals will be too.
“I know some societies say they will lose bloodlines if they act too tightly on it, but I don’t think there’s a bloodline anywhere that would justify breeding PSSM-positive stock,” she said. “It’s such an awful disease and it’s time it stopped. I don’t care about any other society if they don’t want to do it. It’s time our society grasped the nettle and dealt with it.”
The BApS is offering 50% reductions on registration fees in this anniversary year, which Ms Moore said would help negate the cost of the testing.
British Veterinary Equine Association (BEVA) veterinary projects officer Lucy Grieve told H&H BEVA welcomes the society’s decision.
“PSSM1 is an inherited muscle disorder that can cause a range of clinical signs, including exercise intolerance, muscle stiffness, pain and episodes of tying up, with the potential to have a significant impact on equine welfare,” she said. “From a veterinary perspective, identifying affected horses through genetic testing supports informed breeding decisions and can help reduce the risk of passing this condition to future generations. The society’s proactive approach is, therefore, a positive step towards improving the long-term health and welfare of the breed.”
The Appaloosa Horse Club UK
A spokesperson for the Appaloosa Horse Club UK (ApHC UK) told H&H the society has “taken a proactive approach to managing PSSM1 for over 15 years”.
She explained that mandatory testing for current and new licensed stallions was introduced in 2011 after a unanimous AGM vote.
Following a unanimous vote by members at our AGM in November 2010, mandatory PSSM1 testing for all licensed stallions was introduced from 1 January 2011. The requirement applied to both new and existing licensed stallions, with the aim of protecting the health and future of the Appaloosa breed.
This was followed by testing breeding mares and new registrations from January 2012, with results recorded in horses’ passports. Alongside testing, the ApHC UK focuses on educating and supporting owners of horses testing positive, including sharing information about appropriate veterinary advice, management, diet and exercise.
Our approach is to address PSSM1 at the breeding-stock level, because PSSM1 is inherited, knowing the status of both sire and dam enables breeders to make informed decisions before a foal is conceived. Where both parents are verified negative, their offspring are considered ‘negative by parentage’.
Looking back over the past fifteen years, our breeders have embraced this approach, prioritising PSSM1-negative breeding stock while successfully maintaining important Appaloosa bloodlines in the UK. Our objective has been not simply to identify positive foals after birth that would face an uncertain future, but wherever possible to prevent the mutation being passed to the next generation.
The ApHC UK welcomes initiatives by other breed societies to strengthen PSSM1 controls. Horse welfare should transcend organisational boundaries, and we would welcome greater collaboration between breed societies to share knowledge, experience and best practice around PSSM1 and other hereditary conditions.
Ultimately, we all share the same goal: Protecting the health of our horses and preserving the future of the breeds we represent
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Eleanor is an experienced journalist who spent over eight years working for local and national newspapers before joining H&H as news editor in March 2016. Passionate about equine welfare and exposing the truth, Eleanor has reported on all aspects of the industry, from Brexit to anti-bullying campaigns, and from dressage rules to mules. Her sport of choice is showjumping, in which she competes her own horses, and she also enjoys reporting at local jumping shows through to international championships.