New thinking suggests that both shivers and stringhalt (as explained here) may have similarities to certain muscle disorders that can be managed effectively with a change in diet.

Findings from a researcher in America suggest that both these conditions may be related to ERS, the muscle syndrome that we most commonly refer to as “tying up”.

While the name of Dr Stephanie Valberg is synonymous with defining certain cases of ERS into two new syndromes, polysaccharide storage myopathy (PSSM) and recurrent exertional rhabydomyolosis (RER), a second researcher, Dr. Beth Valentine, a vet from Oregon State University, has now made the link between a related condition, equine polysaccharide storage myopathy (EPSM), and muscle conditions of heavy breeds.

In her opinion, shivers and stringhalt are manifestations of EPSM in these horses.

In susceptible horses, both conditions seem to centre on the rapid accumulation of glycogen in muscle cells after starchy, sugary meals, which in turn causes damage to the cells. Management practices have been proposed to reduce the likelihood of occurrences, involving a chance in diet and exercise patterns.

Dietary changes involve reducing the amount of starch and sugar in the diet, replacing them with fibre and oil, with training adaptations to make muscles burn fibre and oil as energy sources.

These changes are not a panacea, however, and will not eradicate shivers or stringhalt in every case, pointing to the gaps in our knowledge about the interactions between the nervous system and muscle function.

Feeding the shiverer

  • Prevent excess accumulation of carbohydrate in the muscles, by diet, exercise and short lay-off periods.
  • Diets should be high in fibre and oil and low in starch and sugar.
  • Starch and sugar foods include mixes (typically a minimum 25% starch and sugar, but often well in excess of 30%) and cereals (oats 50%, barley 60% and maize 70% starch, and minimal sugar), and grass (2-3% sugar in every bite).
  • Draught horses and part-breds tend to be good doers and therefore require less food to sustain them. This makes it easier to avoid high-energy, high-starch mixes.
  • A typical diet of 8kg hay, 3kg chop and 1kg oil supplies 3,500g fibre, 190g starch and 900g oil per day. Some horses dislike this much chop and oil, and so a handful of chop, 4kg of a low starch compound and a generous glug of oil will supply 3,200g fibre, 500g starch and 650g oil. These levels are compared with feeding mix at similar levels.
  • This feed feature first appeared in H&H (31 October 2002)