2026 Volume 79 Issue 2 Pages e15-e20
Thelazia callipaeda is a zoonotic nematode that parasitizes the eyes of dogs, cats, humans, and various wild mammals, and is transmitted by drosophilid flies of the genus Phortica. In this study, we diagnosed 13 canine cases of thelaziasis in a mountainous region of Kanagawa Prefecture, with an average annual incidence rate of 0.26%. The affected dogs included 9 males and 4 females, with a median age of 10 years and a median body weight of 13.1 kg. Twelve dogs resided in mountainous areas, and 10 were kept indoors. Heartworm preventatives had been administered in 6 cases, yet most diagnoses were made between June and December. The median number of worms removed per dog was 3 (range: 1-15). Worm removal was effective in 10 of 12 cases (83%), while 3 dogs required subcutaneous ivermectin injection. Thelaziasis may be spreading to new endemic areas, and it should be considered in the differential diagnosis of dogs presenting with ocular symptoms, taking their geographical environment into account.
