Equine Rhabdomyolysis Syndrome (ERS) – Elementary Level

Read the following information and then complete the quiz questions at the end of the page to test your knowledge and earn AMTRA points.

This resource will introduce you to the following topics:

What is ERS?

Previously known as Tying-Up, Azoturia and Monday Morning Disease, ERS stands for Equine Rhabdomyolysis Syndrome, and is the most common name used to describe muscle disorders in the horse.
Affected horses often have an underlying susceptibility to a muscle problem that is triggered by other things including exercise, diet, electrolyte imbalance, infections and even the weather.
ERS can be sub-divided or defined by two different types of muscle problem: Exertional Rhabdomyolysis (ER), which may be sporadic or chronic (recurrent, known as RER), and Polysaccharide Storage Myopathy (PSSM).
Some ERS suffers don’t appear to have any underlying muscle defect, and so inappropriate diet and management are the probable culprits in these cases.
Having a balanced diet with a good level of antioxidant nutrients and additional electrolytes is important for all horses with ERS.
Working alongside your vet and a nutritionist is key when managing horses with ERS.

Horses with this condition have abnormal muscle contraction.
Thoroughbreds, Standardbreds and Arabs are particularly prone to this condition.
It most commonly occurs when horses are working at speed and is also associated with nervous, excitable or stressy individuals.
Trigger factors for RER include high cereal diets and being held back when training at speed.
For individuals prone to RER, ensuring a sufficient fibre intake and providing slow-release energy sources as an alternative to starch are key in their management.

At 12.5MJ/kg of digestible energy, Alfa-A Oil is Dengie’s highest energy fibre feed but provides only 4.5% naturally occurring sugar and 2% starch.
Alfa-A Oil combines chopped alfalfa with a rapeseed oil coating.
Feed alongside the recommended amount of a fortified feed, e.g., a low starch mix or cube, a broad-spectrum vitamin and mineral supplement, or a balancer to provide a balanced ration, along with added electrolytes.

Combining precision-dried grasses and alfalfa with a rapeseed oil and molasses coating with added spearmint, Performance Fibre is designed with the fussy feeder in mind.
At 12MJ/kg of digestible energy, Performance Fibre has a calorie level equivalent to a conditioning feed but with only 12% sugar and 1.5% starch.
Feed alongside the recommended amount of a fortified feed, e.g., a low starch mix or cube, a broad-spectrum vitamin and mineral supplement, or a balancer to provide a balanced ration, along with added electrolytes.

Alfa-Beet is a high calorie fibrous mash for the performance horse, providing 10.5MJ/kg of digestible energy and only 5% sugar and 2% starch.
Use Alfa-Beet alongside any of Dengie’s fibre feeds as a way of further increasing calorie intake or as a palatable mash which is particularly useful for hiding electrolytes.

Whilst we’ve highlighted three key feeds, there are many other feeds in the Dengie range suited to horses with this problem, including Alfa-A Molasses Free, Healthy Tummy and Alfalfa Pellets, as well as Dengie’s Grass Range.

Dengie feeds suitable for horses with ers

Horses with this condition have a defect in how carbohydrates are stored and/or utilised in the muscles.

PSSM is further divided into two groups: PSSM Type 1 and PSSM Type 2.

This is caused by a genetic mutation found in more than 20 breeds of horse, with the highest prevalence in European Draft horses. Quarter horses and Appaloosas are also affected.
Horses with this condition have much higher levels of muscle glycogen because they don’t break down glycogen in their muscles as easily as healthy horses, due to a mutation of the enzyme Glycogen Synthase 1 (GYS1).
High levels of muscle glycogen can make it difficult and painful for these horses to move, resulting in symptoms ranging from laziness to hard and firm muscles over their hindquarters and a complete reluctance to move.
Management of symptomatic horses includes a diet and exercise geared towards reducing excessive glycogen storage.

Management of PSSM Type 1 horses includes:

Low intakes of sugar and starch, along with grazing management as per recommendations for a laminitis-prone individual.
Affected breeds tend to be good doers, so maintaining at a healthy weight is just as important as for a laminitis-prone horse.
Daily exercise, which can include in-hand exercise or turnout, is vital to managing this condition in conjunction with dietary changes.

PSSM Type 2 refers to cases that aren’t caused by the GYS1 genetic mutation.
PSSM Type 2 is more prevalent in Warmbloods and is often detected with poor performance and a drop in energy levels after a short period of exercise.
Dietary recommendations aren’t as restrictive as for those with PSSM Type 1, but there is a focus on a balanced diet with adequate good quality protein.

One of Dengie’s lower calorie, sugar and starch feeds at just 8.5MJ/kg of digestible energy, 2.5% sugar and 1.5% starch.
Use as a bucket feed or partial forage replacer.
Combine with a broad-spectrum vitamin and mineral supplement or balancer for a balanced ration.

A low-calorie, high-fibre feed with added herbs, yeast, and prebiotic for digestive support.
It supplies only 8MJ/kg of digestible energy, 6.5% sugar and 2% starch.
Ulser Lite is molasses free and can be used to totally replace the forage ration for the good doer.
Combine with a broad-spectrum vitamin and mineral supplement or balancer for a balanced ration.

The lowest calorie feed in the Dengie range, providing just 5MJ/kg of digestible energy, as well as being low in starch and sugar, at 0.5% and 3% respectively.
It combines soft, tasty meadow grasses blended with high-quality oat straw to offer a low-calorie feed with added cinnamon and thyme to tempt fussy feeders. It can also be used as a complete or partial forage replacer for good doers.
It also contains pea hull fibre, which a great source of highly digestible fibre. A range of fibre types is beneficial for digestive health and helps to support a healthy microbiota.
The inclusion of postbiotics supports the gut microbiota for general health and wellbeing.

Low calorie feeds for horses with ERS

ERS can be broadly sub-divided into two different problems – RER and PSSM.
For all horses, ensuring a balanced ration appropriate for their workload is key.
For those with RER, the recommendation is to reduce excitability and the amount of starch in the ration, especially on rest days and with time off.
For those with PSSM, a fibre and oil based ration in conjunction with a suitable exercise regime is essential to managing this condition.