It´s an important cause of life threatening anaemia in horses.

Biting ticks spread the protozoan parasitic infection of the red blood cells from horse to horse. It´s caused by the protozoan parasites Babesia caballi and Theileria equi, which invade the horse's red blood cells.

The disease caused by T. equi is usually more severe than that caused by B. caballi.

The infection can also be transferred from horse to horse by any mean that transfer fresh blood. The symptoms are fever, depression, anorexia, weakness, ataxia, tachycardia, tachypnoea, lacrimation, mucoid nasal discharge, yellow mucosa and red coloured urine.

The clinical disease commonly affects horses that have been introduced to an endemic area, whereas horses that have been born and reared in endemic areas often become symptomless carriers.

These carriers may show symptoms of disease when stressed. Serologic tests are the basis of pre-import tests required by many countries. Specific anti Babesia medication is used to treat babesiosis in horses, with better success for B. caballi than for T. equi.

This article is based in scientific veterinary literature.