Recurrent Exertional Rhabdomyolysis (RER)

What is it?

Recurrent exertional rhabdomyolysis (RER) is a specific form of tying-up seen in Thoroughbreds, Standardbreds, and Arabians. It is an inherited trait caused by abnormal intracellular calcium regulation during muscle contraction. Although the genetic predisposition for RER is evenly divided between males and females, clinical signs of the disease are more often seen in young fillies. Excitement and stress seem to be trigger factors. High grain intakes are associated with tying-up in racehorses.

How can KERx help?

Research conducted at the University of Minnesota in conjunction with KER suggests that replacing much of the grain in the diet with a low-starch, high-fat feed will significantly decrease the amount of muscle damage in RER horses. In a feeding trial, five Thoroughbred horses with RER were exercised on a treadmill for five days a week while they consumed hay and a variety of energy supplements for three weeks at a time. When the daily caloric intake of a high-starch ration was kept low (21 Mcal DE/day), the horses had lower post-exercise serum CK than when this feed was increased to provide 28 MCal DE/day. In contrast, if extra calories were provided from a low-starch, high-fat feed (RE•LEVE, see below) rather than a grain supplement at 28 MCal/day, no increase in post-exercise serum CK activity occurred. No significant differences in muscle glycogen or lactate concentrations were apparent in these studies.

Most horses with RER have medium to high energy requirements and need significant calories supplied above those found in the forage portion of the ration. An appropriate feed should be fortified to be fed at fairly high levels of intake (4-6 kg/day). It should be low in NSC (<10%), high in fat (>10%), and supply a significant portion of its energy as fermentable fiber.

RE•LEVE Original is a high-calorie feed specifically formulated for horses requiring low-starch diets. RE•LEVE Original maintains its energy density by relying on fat and fermentable fibers rather than starch sources for the majority of its calories. Alternative energy sources such as high-fat stabilized rice bran along with super fibers beet pulp and soybean hulls provide highly digestible and readily available energy.