Fat horses and ponies are prone to trouble, not least laminitis and metabolic syndrome.

Grazing muzzles are becoming more popular as a way of limiting the amount that horses at grass can consume, but do they work? And can a horse eat more grass through the muzzle if he is on a pasture of fine-leafed, soft grass compared with a thick, coarse-leafed species?

Scientists in Minnesota, USA, investigated these issues by grazing four horses in four separate paddocks, each planted with a single grass species.

The results revealed that there was no difference in the quantities of each grass species that the horses could consume through the muzzle. Wearing the muzzle reduced the dry matter intake by an average of about 30%.

It appears that grazing muzzles do work and that, in a mixed grass pasture, horses will not selectively choose one grass species over another any more than they would without the muzzle.

This article was first published in Horse & Hound magazine (18 September 2014)