Understanding Tying Up Syndrome

Tying-up syndrome, or rhabdomyolysis, is a myopathy (a disorder affecting the body’s muscle system) that causes muscle-cell destruction and decreases an affected horse’s performance.

Common systems include painful muscle cramping and hardening as well as severe increases in muscle enzymes that can be detected through laboratory testing.

Exertional rhabdoyolyses are disorders that typically occur in horses performing exercise beyond their conditioning status, or horses performing strenuous exercise after a period of rest and inactivity. This disorder may be sporadic or can chronically recur in some affected horses.

Risk factors: Inadequate conditioning, high carbohydrate intake, deficiency in vitamin E and/or selenium, hypothyroidism, and bacterial or viral infections are some of the risk factors that veterinary researchers have considered. However, the evidence supporting these factors is still unclear. Since female horses seem to be predisposed, hormones may be a factor. Differential diagnoses of lameness, colic, pneumonia, back pain or neurological diseases can be ruled out by a complete physical examination and with lab tests of blood and urine.

Treatment: Treatment includes rest, intravenous and/or oral fluid therapy, non-steroidal anti-inflammatory drugs (NSAIDS) for pain control and, if necessary, sedatives to control anxiety. If deficiencies in vitamin E and selenium are identified, supplements should be provided. In the disease’s acute stages, horses should not be forced to move, and their return to exercise should be based on improved lab results as well as their willingness to move.

Recumbent horses should have soft bedding to prevent injury, and their caregivers should encourage them to stand and turn every few hours to avoid bedsores. Horses unable to stand should be turned every few hours. In some cases, it may be necessary to use a sling to help an affected horse stay upright. However, horses that are in pain should not be forced to stand for extended periods of time.

Prognosis: The prognosis for recovery is generally favourable as long as the animal is treated early enough and doesn’t develop complications such as kidney failure. The recovery time depends on the severity of the disease; an adequate rest period and gradual return to exercise are required. Proper conditioning and regular exercise — including pasture turn-out — are also recommended.