Reading time 5 minutes  

Summary

  • PSSM (Polysaccharide Storage Myopathy) is a genetic muscle disorder in horses.
  • PSSM causes muscle pain, stiffness, and cramps, particularly with little movement.
  • Diet plays a crucial role in supporting PSSM horses.
  • Feed with low starch and sugar helps maintain stable blood sugar levels.
  • Fats, such as vegetable oil, can be used as an alternative energy source.
  • Balanced nutrients like Vitamin E, magnesium, and selenium are important for muscle health.
  • Regular exercise and well-balanced feeding management improve the well-being of horses.
Inhalte Verbergen
1 Summary
2 Genetics
3 But does the horse become ill?
4 Feeding
5 Exercise!

Genetics

More and more horses are being diagnosed with the PSSM gene, especially among Western horses, as genetic testing is much more commonly carried out in this group compared to other breeds. Systematic studies and practical experience have shown that PSSM occurs genetically in almost all breeds, although with varying frequency.

There is also a large number of cases with clinically manifest PSSM that are genetically negative. However, the fact remains that for breeders, the diagnosis of “PSSM positive” for their offspring is often largely fatal, as such a horse will not fetch as much money as a “healthy” one.

But does the horse become ill?

It is often overlooked that the presence of a genetic variation does not necessarily mean that an animal is sick. Especially in the case of PSSM, the presence of the gene is merely an indication of a predisposition. Whether PSSM manifests as a disease or not depends entirely on the circumstances of life, such as management, exercise, and feeding.

In this sense, PSSM is essentially the ultimate civilisation disease, as it only manifests when horses are not exercised enough and are provided with an overly rich diet.

The trend in our day and age of not using horses as working or ridden animals anymore, but instead allowing them to stand around for most of the time, combined with today’s much richer hay and often generous feeding of muesli, carrots, and various treats, is the real problem.

PSSM actually means the opposite of insulin resistance (diabetes). In insulin resistance, the muscle cells no longer take in enough sugar.

In contrast, with PSSM, even the slightest increase in insulin levels causes the muscle cells to take in a large amount of sugar. For wild horses living in steppes, semi-deserts, or barren tundra landscapes, this is a brilliant survival aid: even the smallest amounts of energy are enough for their muscles to have plenty of energy for movement. However, it becomes problematic when energy-rich food is provided, and the horse simply stands around in a stable open or closed barn.

Feeding

The trend of feeding such horses a diet rich in fat and protein to provide them with enough energy completely misses the needs of the organism. Instead, these horses should be fed and kept the way wild horses are: with sparse food and plenty of movement. Scientific studies have shown that not only can this approach prevent the onset of PSSM, but about 75% of clinically affected horses also recover through this method.

In practical terms, this means sending hay samples for analysis and checking the nutritional values. Sugar content should definitely be below <10% preferably under <6%. Protein and fat can be a little higher. Such low-sugar hay should be available continuously for 24 hours, as horses with PSSM are also permanent feeders, and food breaks are detrimental to their health too.

Avoid everything else that is typically added to the feed – even grain-free or fat- and protein-rich mueslis are off-limits here! The horses already get plenty of energy from their lean hay, so nothing else needs to be added. If the hay is low in protein, then protein can be supplemented, but it should be fiber-based, such as sainfoin, hay cobs, or lucerne. Along with a proper (low-sugar and low-starch!) mineral supplement, a salt lick, and plenty of fresh water.

Sainfoin for horses
If you have low-protein hay, protein can be supplemented, but preferably fiber-based, such as sainfoin. © OKAPI GmbH

Exercise!

The rest must be managed through movement. Horses with a predisposition to PSSM must be exercised every day; just turnout and even the paddock trail are not enough. A daily session that gets the horse sweating is essential – meaning riding in a way that ensures the horse works hard enough to break a sweat.

This depletes the energy reserves in the muscles and helps prevent PSSM from manifesting as a disease. Therefore, a horse with a PSSM predisposition is quite economical to maintain, as you save money on concentrated feed while still having a willing, energetic horse under saddle every day.

If a horse already has clinically manifest PSSM, then feeding and working should only be done under therapeutic supervision. With the right management, such horses can recover and stay healthy, but it is important to seek advice from someone experienced in this subject.

Team Sanoanimal
Latest posts by Team Sanoanimal (see all)