Page 472 - The Veterinary Care of the Horse

though the horse needs them for other metabolic processes. Diets with a low DCAB can

predispose to ERS.
VetBooks.ir • Viruses such as the equine influenza virus and equine herpesvirus 1 appear to increase

some horses’ susceptibility.
• Temperament can be a factor as nervous excitable animals seem to be more at risk.

• Hormonal factors may play a part as the incidence is higher in females, particularly when

they are in season.
• Horses experiencing ERS are rarely deficient in vitamin E or selenium so a deficiency of

either is unlikely to be a cause. However, both of these antioxidant micronutrients
scavenge the damaging free radicals that are generated by exercise. It may be that horses

with ERS generate more free radicals than normal horses, thus accounting for why
supplementation anecdotally appears to help in some cases.

• Genetic factors may be important. Work in the United States has identified an inherited
form of recurrent equine rhabdomyolysis.

• Horses with polysaccharide storage myopathy (PSSM) are prone to experiencing ERS.

• Stress and climatic factors can trigger ERS.

• Endurance horses may develop ERS due to a combination of overheating, dehydration,
electrolyte imbalance and exhaustion.

• Anything that reduces the blood flow to skeletal muscle can predispose a horse to ERS.
Examples include lameness and muscle tension.

• Abnormal calcium transport at cellular level is another area currently being investigated.

Treatment

The aim of treatment is to:

• minimize the pain and anxiety
• prevent further muscle damage

• restore fluid and electrolyte balance

• maintain adequate kidney blood flow to minimize the accumulation of myoglobin in the

tubules as it is toxic and may cause permanent kidney damage.

The management and medication of affected animals varies with the severity of the
condition. The following may be included in the treatment:

• A tranquillizer to relax the horse. Acepromazine (ACP) will decrease the horse’s anxiety
and may increase the blood flow through the muscles. If the horse is in severe pain a