Paradoxical Pseudomyotonia

What is Paradoxical Pseudomyotonia?

Paradoxical Pseudomyotonia (PP) is a genetic disorder caused by a recessive mutation that has recently been identified in English Cocker Spaniels and English Springer Spaniels.  Currently we don’t know how prevalent the mutation is in either breed, or if it is more prevalent in working or show lines.  

A paper published in 2019 by Stee et al described the disease in seven clinically affected dogs: four English Springer Spaniels (ESS) and three English Cocker Spaniels (ECS).  Click HERE to read this paper in full.

In February 2023 a paper published by Van Poucke et al used whole genome sequencing to identify a mutation in the SLC7A10 gene that causes the disease.  Their study also included four additional cases, all English Springer Spaniels, bringing the total of confirmed cases to eleven.   Click HERE to read this paper in full.

What are the symptoms of PP?

In dogs with PP, muscles take longer to relax (remain stiff) after voluntary contraction (mainly during exercise).  When having an episode, they experience the sudden onset of muscle stiffness, causing them to look like they are “running in a computer game” or getting “stuck” while climbing steps or performing small jumps.  

Signs of the condition are first seen between the ages of three months and two years.  Episodes vary in severity and frequency but can happen 15 times a day in some cases.  They usually last for a few minutes and resolve with rest.  

Click on the links below to see videos of PP episodes (from the original publication by Stee et al)

What is the outlook for affected dogs?

The severity and frequency of episodes tend to remain stable or decrease with age, and episodes can be decreased or eliminated by avoiding triggers (usually strenuous exercise).  That said, the disease reduces the quality of life of affected dogs.

Is there a DNA test for PP?

A DNA test is available in the UK from CAGT (Canine Genetic Testing) laboratory and can be ordered online directly from their website.  

The PP variant is recessive, so it is safe to breed from carriers (to maintain genetic diversity) provided either the sire or the dam is clear of the variant.  For further information on 'Understanding Genetic Inheritance', click HERE.

Should breeders routinely use the PP DNA test?

The 2023 published paper estimates a mutation frequency of 2.5% in UK ESS – if this is accurate then we would expect a small handful of ESS cases each year.  However, the numbers of dogs that have been screened for the mutation are extremely limited and there are currently no reliable estimates of the mutation frequency in either Cockers or ESS.   

As the discovery of the mutation is very recent, based on a small number of clinically affected dogs, and there appears to be a significant variability in the severity of the symptoms, we are currently gathering more information (working with the KC and geneticists) before any decision is made on whether this test should be added to the list of tests officially recognised for the Breed. 

Click on the link below for a summary by Dr Cathryn Mellersh, Head of the Kennel Club Genetics Centre (KCGC) Group

We would be extremely grateful if owners would contact us if your ESS has any of the symptoms described above.  We'd also be grateful if you could report online any confirmed diagnosis of PP.  All information provided will be treated in the strictest confidence.

For further information or advice about PP, please contact the

ESS Breed Clubs Health Co-ordinators