Management of Ocular Setariasis in Ponies with Local Ocular Ivermectin Injection

Abstract

Equine ocular Setariasis is a vision threatening disease of equine, caused by Setaria spp. This clinical communication describes two equine ocular Setariasis cases which were successfully treated with a single dose of ocular Ivermectin injection. Two ponies were referred to the Ambulatory clinic, Faculty of Veterinary Medicine, Peradeniya, Sri Lanka with the complaint of observation of a moving worm inside the anterior chamber of the eye since few days. The cloudiness of the cornea has been gradually increasing since the day the owner observed the worm inside the eye. Upon the clinical examination, both ponies were normal except the signs related to the eye condition including extent lacrimation, and moderate, unilateral corneal opacity. On close examination of the affected eye, the swirling movements of white thread like worm swimming continuously in aqueous humor of anterior chamber of the eye was evident in both cases. The ponies were properly restrained. 0.05ml of 1% ivermectin was loaded in to a sterile 1cc syringe with a 29G needle and was double diluted with normal saline. While the pony’s head was held firm, the needle was inserted in to the anterior chamber of the eye and the drug was released slowly. Prophylactic eye ointment containing an antibiotic i.e. 3% Tetracycline Hydrochloride (Galentic®) ointment was prescribed to be applied in the eye twice daily. Within an hour after the ivermectin treatment, the movements of the worm became sluggish and the movements were restricted to the most ventral part of the anterior chamber. The worm which was in the anterior chamber died on the same day of treatment. But few days later, the dead worms had triggered an inflammatory reaction in the eye, thus the animals were treated with an ophthalmic preparation containing NSAID i.e. 0.5% Ketorolac Tromethamine (Ketrosan®) ophthalmic solution. The condition recovered without any impairments of the vision or damages to the eye. Treatment of ocular Setariasis is always being a challenge. There are reported cases of successful surgical and medical interventions for ocular Setariasis in equids. This method would provide a less invasive, quick method done using only a single dose of ocular ivermectin injection in order to treat equine ocular Setariasis.