PSSM is one of the most common muscle diseases in horses. The abbreviation stands for polysaccharide storage myopathy. This muscle disease is congenital and genetic .
Polysaccharides, long-chain sugar molecules, are stored excessively. In this article, you'll learn how PSSM in horses progresses, what the signs are, and how you can treat your pet.
PSSM: What does this muscle disease mean for horses?
A common muscle disease in horses is PSSM, polysaccharide storage disease.
In the horse's muscles , long-chain sugar molecules , called polysaccharides, are stored in increased amounts . They are not properly metabolized and are stored as glycogen in the muscle cells. This can result in severe muscle pain.
PSSM is a congenital, hereditary disease that is incurable . Excessive accumulation of polysaccharides leads to dysfunction in muscle cells. Muscle cells subsequently die.
With proper care and feeding of your horse, you can alleviate the symptoms of this muscle disease. PSSM often affects robust animals with strong muscles.
Dressage horses can also suffer from this.
The equine disease PSSM was previously diagnosed primarily in cold-blooded breeds, Paint Horses, and Quarter Horses . However, it can also occur in other horse breeds and types, such as various warmblood breeds, Haflingers, and Freibergers.
What forms of PSSM are there?
PSSM is divided into two types: PSSM 1 and PSSM 2. PSSM 1 is the genetic variant , while PSSM 2 has been little researched so far.
In a horse with PSSM, the glycogen concentration in the skeletal muscles is up to four times higher than in a healthy horse. This causes lasting damage to the muscle cells.
When muscle cells are destroyed, the muscle pigment myoglobin is released . It travels through the bloodstream to the kidneys and is excreted in the urine, which is dark red.
Differences between PSSM 1 and PSSM 2 exist in the causes, symptoms and treatment of the disease.
In a PSSM 1 horse, one or both parents have a genetic defect that is passed on to the young animal.
If the genetic defect is present in both parents, the risk of your horse developing PSSM is extremely high. Your horse is a so-called double carrier . A double carrier is highly likely to pass the genetic defect on to its offspring.
Your PSSM 1 horse is a single carrier if only one of its parents has the genetic defect. The risk of PSSM disease is increased, but your horse does not necessarily develop the disease.
In single carriers, the risk of passing the genetic defect on to offspring is approximately 50 percent . A PSSM 1 horse has a mutation in the glycogen synthetase 1 gene, GYS-1.
In PSSM 2 horses, the cause of the disease is not yet fully understood. A genetic defect is suspected, as in PSSM 1 horses.
However, it has not yet been confirmed as the cause. There are several variants of PSSM 2. Previously, it was suspected that the cause of the disease was a series of sugar molecules.
Certain muscle cells are therefore no longer suitable as energy suppliers.
Many researchers now consider a negative nitrogen balance as the cause of PSSM2. It is triggered by low protein intake and increased protein consumption and leads to muscle wasting. During periods of intense exercise, muscle cells are no longer supplied with essential fuel and die.
The resulting toxin must be excreted through the kidneys and leads to long-term kidney strain. Changes occur in the muscle fibers of a PSSM 2 horse. A mutation of the GYS-1 gene is not present.
All causes at a glance
In horses with PSSM1, the mutation in the GYS-1 gene is the cause of the disease. Even if the veterinarian detects this mutation, the horse does not necessarily develop PSSM.
If your animal has the genetic defect and is not yet ill, it can remain symptom-free if you ensure appropriate feeding and care.
These are the main causes :
- Large amounts of easily digestible carbohydrates in the feed
- Stronger response to endogenous insulin when feeding carbohydrate-rich food
-
Disturbed transmission of excitation in the muscles
- Incorrect feed and incorrect feeding
- Frequent feeding of sugary foods
First signs & typical symptoms: How does PSSM manifest itself in horses?
As muscle cells die, muscle loss can be one of the most common symptoms of PSSM. The horse may appear tired, lame, or clumsy when backing up.
If PSSM is acute, the typical PSSM symptoms are referred to as attacks or relapses, which can occur with varying severity depending on the progression of the disease and the condition of your horse.
The PSSM horse symptoms also differ depending on the type of disease.
After periods of intensive labor , mild attacks occur, manifesting as a curved back, stiff hindquarters, and reluctance to move. Mild colic symptoms may occur.
However, colic can also be caused by changes in the weather .
Moderate attacks can occur even during exercise. The horse stops, appears stiff, and sweats profusely. Noticeable stiffness develops in the hindquarters and croup.
Severe attacks can also occur during work, with symptoms similar to those of colic.
The attacks manifest themselves with heavy sweating and clear signs of colic. The animal suffers from extreme muscle pain and can barely move.
PSSM symptoms include weak hindquarters, severe trembling similar to shivering , and muscle stiffness. The urine is dark red to coffee-brown, as the horse excretes the pigment myoglobin due to the dying muscle cells.
If the horse has PSSM1 , the following symptoms are typical:
- Fatigue and reluctance to move
- Muscle tension and muscle tremors
- Symptoms similar to colic
- heavy sweating even during light work
- Muscle loss in the croup
- Resistance to reversing
If your horse suffers from PSSM2 , the symptoms usually first appear when the animal is already seven to ten years old:
- Sudden change in horse's character, which manifests itself with listlessness or explosive behavior
- Diffuse lameness
- Stiff hindquarters, little ground reach, firm topline
- Muscle loss in the shoulder and hindquarters
- Coordination problems and unusual gait
- Tension, muscle tremors, similar symptoms to lumbar cramps
- Depressions in the muscles
- Increased muscle tension in cold weather
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Try it now!Treatment & Therapy: What can you do?
If your horse exhibits an acute PSSM attack, you should consult your veterinarian immediately . You can avoid dehydration from excessive sweating by providing your horse with plenty of water.
The veterinarian examines blood and urine to determine how advanced the muscle damage is.
Continuous medication is not absolutely necessary. In the case of an acute attack, the veterinarian may prescribe pain-relieving and anti-inflammatory medications .
PSSM2 treatment is carried out as for crusade with monitoring of kidney function .
How is PSSM diagnosed?
If you notice symptoms in your horse that indicate PSSM, the veterinarian should perform a DNA test based on a blood sample .
This test can determine the specific form of the disease. It's possible for a horse to suffer from both PSSM1 and PSSM2 simultaneously. PSSM1 can be detected with a mutation test.
If the PSSM1 test is negative and your horse shows symptoms, a further genetic test for PSSM2 can be performed. This genetic test can also detect the variant. In acute cases, PSSM2 can also be diagnosed with a muscle biopsy.
Feeding recommendation: What you should pay attention to
With proper PSSM horse feeding, you can significantly alleviate your animal's symptoms. Use low-sugar and low-starch feed for PSSM horses, and avoid giving your horse fruit or treats.
Selenium helps horses relax tight and stiff muscles. Vitamin E promotes the regeneration of damaged cells.
PSSM horse feeding varies depending on the type of disease.
For PSSM1 the following applies:
- Slow transition to suitable food
- No silage because the pH value is too high
- Protein-rich feed
- Roughage with the lowest possible sugar content, especially hay
- Small amounts of concentrate or no concentrate at all
- Feeding breaks no longer than four hours
Our tip:
If you have PSSM2 , you should also avoid giving concentrate feed if possible. Your horse has a protein requirement six times higher than a healthy animal.Symptoms can be alleviated with additional amino acids and antioxidants. Amino acids support muscle building.
Optimal posture: The best tips
Since constant exercise is important for a horse with PSSM, an open or active stable is recommended. Daily grazing or access to a paddock are also suitable .
At the beginning of the paddock season, slowly get your horse used to the young, starchy grass.
To avoid stress, you should maintain a daily routine and regularity . Avoid stress and excitement for your pet.
Can exercise and horse training help with PSSM?
Exercise and training are important to maintain muscles and counteract symptoms.
When training, maintain a consistent intensity and balanced movement to ensure glycogen is depleted from muscle cells. Ensure variety and gradually increase the intensity after a burst.
After training, a sufficiently long cool-down phase is important so that your horse can break down the metabolic products.
Conclusion
PSSM is a genetic muscle disease in horses that is incurable. Excessive glycogen storage occurs in muscle cells.
This results in the death of muscle cells, which causes severe pain for your pet. A genetic test can determine whether the condition is PSSM1 or PSSM2 .
The disease occurs in bouts. If a flare-up occurs, you should consult a veterinarian.
With proper feeding, keeping your horse in an open or active stable, and plenty of exercise, you can reduce symptoms and improve your horse's quality of life.
FAQ
Can you ride a horse with PSSM?
Regular training is important for PSSM. You can ride your horse, but you should ensure you walk at a sufficient pace at the beginning of training so that the muscles warm up.
How much does a PSSM test for horses cost?
The cost of a PSSM test for a horse depends on how many individual tests are required. If PSSM1 cannot be detected, it will be more expensive, as testing for PSSM2 and the respective variant is required. The costs can also vary by state and laboratory.
How old does a horse with PSSM get?
The life expectancy of a PSSM horse can be almost normal if the disease is diagnosed early and you pay attention to proper care, lifelong special feeding and targeted training.
Important:
Pferdegold is not a substitute for veterinary diagnosis or treatment. The information contained in this article is for general informational purposes only and is intended to help improve your horse's well-being.
Pferdegold products do not treat or cure diseases , but rather support your horse in compensating for nutritional deficiencies through targeted nutrient intake .
However, they are not a substitute for professional advice from a veterinarian or specialist. If your horse has any health problems, we strongly recommend consulting a veterinarian. Pferdegold assumes no liability for decisions made based on the information provided here.
