Intra- and periocular parasitic infection is rarely reported in the dog. The aim of this study is to describe the ocular manifestations of 60 cases of canine Onchocercosis in Greece, the largest series of cases ever reported, and to suggest the most suitable and effective treatment of the disease.

Sixty animals included in this study, admitted to the Ophthalmology Unit, Clinic of Surgery, School of Veterinary Medicine, AUTH, between 1997 and 2003, having similar ocular manifestations. The male female ratio was 3:1. Thirty-seven animals had bilateral ocular manifestations while the rest of them had unilateral. The most common ophthalmic manifestations in all animals were mild to severe periorbital swelling, conjunctival congestion, exophthalmos, photophobia, lacrimation and subconjunctival periocular masses. Diagnosis was based on clinical and ophthalmologic examination while ultrasound and histopathology of small skin snips collected from the head or the abdominal region was not always helpful. Surgical excision of the periocular masses was performed in all animals unilaterally. Steroids and antibiotics were administered locally and systemically while antiparasitics were given systemically.

The cyst-like or granulomas formations that removed consisted mainly of granulation tissue and alive parasites emerging from the masses. The parasites identified as Onchocerca spp. The eyes treated surgically and medically appeared to have a quicker response to the treatment, related to the ones treated only medically. The treatment was successful in all animals and no recurrence of the disease has been noticed till now.

Canine periocular onchocercosis represents an important disease in Europe with ophthalmologic significance. It should be considered in the differential diagnosis of any ocular and periocular masses in dogs. Diagnosis is mainly based on clinical appearance. Successful treatment is achieved by surgical excision of the parasitic nodules, in combination with antiparasitic medications. Canine ocular onchocercosis may also provide an experimental model of human onchocercosis, the world's second most prevalent infectious cause of blindness in humans.