Today I’ve been sorting through old photos and came across these microscope shots of grass from a nutrition internship I did (in 1999) at the Roslin Institute, part of the Edinburgh Royal Dick Vet School and home of Dolly the Sheep. The superman-logo shaped ovals are stoma, but the dog-bone and four-leafed clover shapes are

Phytoliths – tiny lumps of silica, the same substance that forms the basis of sand and glass. This is what horse’s teeth are evolved to combat, the reason they need to be long. When the tooth’s surface is ground down new tooth can take it’s place, but without this sandpaper teeth will continue to “grow”, and gain sharp edges. Being tough lumps the phytoliths survive into hay, but aren’t present in pellets, hard feed, or some low calorie options. There are lots of reasons that horses need access to grass and/or hay, but dental health seems to be one that’s often overlooked.