New parasite treatment alternative to surgery

Brooke India's research into an alternative treatment for a serious eye condition could save the sight of many working equids.

Horses grazing in a rural area of India

Parasites are organisms that live on or in another organism - the host. They can cause poor health and sometimes serious illness.

Working equids in poorer communities are vulnerable to parasites. One parasite in particular - Setaria equina – is common among horses. Transmitted by mosquitos, it can lead to a serious eye condition called ocular setariasis, which, if left untreated, can cause blindness.

Treatment options have been limited. Surgical removal of the parasite tends to be the most common. But surgery requires a high level of skill, and anaesthetising an animal is difficult in remote areas where sterile surgical facilities are unavailable. The risk of permanent eye damage is high.


Brooke India’s research team wanted to find out if there were any possible alternatives to surgery for this condition. They contacted parasitology experts and equine ophthalmologists, and learned that a treatment called Ivermectin might be an option.

Despite this medication being widely used in other animals, little research had been reported with equines so no guidance on its use existed. Research was necessary to find the correct strength and dose to make it effective in equines.

Starting with a small dose of the medication, seven horses with this eye condition were treated every four days. Initial doses were, however, insufficient to completely kill the parasite so the treatment was revised and the dosage increased.


Results from the trial showed this medication was effective in horses and could be used as a primary treatment for this dangerous eye condition, providing a feasible alternative to surgery.

Both the effectiveness of the treatment and the consequent drop in the need for surgery will have a potentially huge impact on the welfare of working equids at risk of being infected by this parasite.


This new alternative treatment to surgery will be integrated into veterinary and paraveterinary training to ensure it becomes part of routine clinical practice.