Abstract
BackgroundThe present study evaluated the therapeutic effectiveness of moxidectin 1.0% (w/v) and imidacloprid 10% (w/v) (Advocate® spot-on solution for cats, Bayer Animal Health) against natural infections with the eyeworm Thelazia callipaeda in cats. This study was conducted as a GCP, negative-controlled, blinded and randomised field study in privately owned cats living in an area in southern Italy where T. callipaeda is enzootic.MethodsThe study was carried out in 30 cats (19 females and 11 males, aged from 8 months to 5 years, weighing 1.2–5.2 kg) of different breeds, naturally infected by T. callipaeda. At study inclusion (Day 0), animals were physically examined and the infection level was assessed by examination of both eyes for clinical score and live adult T. callipaeda count. Each cat was weighed and randomly assigned to one of the treatment groups (G1: Advocate, G2: untreated control). Clinical assessments and T. callipaeda adult counts were performed on Day 14. At the study completion visit on Day 28, clinical assessments and counts of T. callipaeda adults and larvae were performed. All cats were daily observed by their owners and general health conditions were recorded during the entire period of the study.ResultsThe primary effectiveness variable was the percentage of animals in G1 group (Advocate) showing a complete elimination (parasitological cure) of adult eye worms at Day 14 and Day 28 . The effectiveness of the treatment in the G1 group was 93.3 and 100% at Day 14 and Day 28 , respectively, when compared to group G2. Total worm count reduction from both eyes for Advocate was 96.3% on Day 14 and 100% on Day 28. Clinical data were confirmed by the examination of conjunctival pouch flushing. An overall reduction in the number of cats with lacrimation and conjunctivitis was observed following treatment despite the fact that in a few cats treated with Advocate clinical signs persisted due to the chronic nature of the disease.ConclusionsBased on the results of the present trial, a single dose of Advocate was found to be safe and highly effective in the treatment of natural T. callipaeda infection in cats.
Highlights
The present study evaluated the therapeutic effectiveness of moxidectin 1.0% (w/v) and imidacloprid 10% (w/v) (Advocate® spot-on solution for cats, Bayer Animal Health) against natural infections with the eyeworm Thelazia callipaeda in cats
The average number of adult T. callipaeda specimens observed in G1 and Study group of untreated cats (G2) was 2.13 and 1.87, respectively
The number of parasites and the number of cats with clinical manifestations in each eye was homogenous among groups (F(1,28) = 0.767, P = 0.389 and Fisher’s exact test, P = 0.500, for the number of parasites and for lacrimation, conjunctivitis and ocular discharge, respectively)
Summary
The present study evaluated the therapeutic effectiveness of moxidectin 1.0% (w/v) and imidacloprid 10% (w/v) (Advocate® spot-on solution for cats, Bayer Animal Health) against natural infections with the eyeworm Thelazia callipaeda in cats. Thelazia callipaeda is a spiruroid nematode residing in the conjunctival pouches of dogs, cats, wild carnivores and humans. Since its first description in dogs from northern Italy [1], reports of thelaziosis have increased showing a wide distribution throughout European countries and its capability to provoke ocular manifestations such as conjunctivitis, keratitis, corneal opacity and ulcers [2,3,4] due to the mechanical action of the adult parasite on the conjunctival and corneal epithelium. The increase of infections in both animals and humans is related to the presence of the T. callipaeda vector, Phortica variegata, a drosophilid of the subfamily Steganinae which, in Europe, acts as intermediate host of the eyeworm [12, 13]. Many treatments have been proposed, including topic instillation of organophosphates [17] or moxidectin [18]; these had major local side effects
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