The frog of a horse’s hoof is meant to be a wide based triangle, with a shallow diamond shaped dimple towards the heels. This dimple is called the central sulcus and is part of the shock absorption system of the hoof (see hoof function page for more details).
A horse should never react to a frog being touched. A healthy frog can not be damaged by a hoof pick and you should always be really thorough in cleaning out the grooves to either side of the frog and the frog sulcus.
When a horse’s soft tissues are weaker than they should be, the heels of the hoof often contract towards each other and squash the frog into a much narrower triangle. This contraction also squashes the central sulcus and can lead to a very deep and sometimes sore crack in the back of the foot.
Many owners are worried about this crack, but are unsure how to care for it if their horse flinches when a hoof pick or other object is pushed into the crevice.
The first step is to carefully clean the sulcus, then pack the crevice with something soft and soothing that won’t irritate the tissues and will prevent grit from being trapped deep in the frog.
The video below shows how I like to achieve this: