Rubbed raw

Persistent itching is hard to live with, causing both physical and mental distress. Kieran O’Brien MRCVS explains what may cause it in horses, and what to do

- Kieran O’Brien MRCVS

WE all find relief in scratching the odd itch that occurs for no particular reason, and horses are probably no different. But in the majority of cases in horses there is some skin irritation that provokes the itching response, in an attempt to relieve it.

This irritation is almost always allergic or parasitic in origin. Some irritations are seasonal (for example lice infestation or sweet itch) and others (for example leg mites) are present all of the time.

A lousy problem

TWO species of lice infest horses; one bites the skin and the other feeds on its surface. Lice are almost entirely a winter and early spring problem when the coat is long, and the horse is unclipped.

They may persist unnoticed in low numbers in the skin during the summer, but the numbers gradually rise once the winter coat develops and the skin surface temperature becomes consistently warm.

Lice cause itching chiefly of the neck, chest, rump and mane. In horses kept in groups, all eventually become infested due to contact.

Lice are host-specific, so there is no risk of infestation of other species, including humans.

The lice are 3mm to 6mm long and if the hair is parted, they can be spotted deep in the coat and in the mane.

Applying a rug for an hour will bring the lice to the surface, where they can be more easily seen.

Louse eggs (nits) can also be seen in the coat, are 1mm to 2mm long and are “glued” to the hair shafts (pictured, left). This differentiates them from, for example, hay seeds, which will fall free from the hair if some hair is plucked.