A report of the unusual lesions caused by Thelazia gulosa in cattle

This is a case report of unusual lesions caused by Thelazia gulosa in cattle. After several ineffective treatments of suspected infectious keratoconjunctivitis in calves and cows, T. gulosa was found associated with retrobulbar granuloma-like masses. The masses with multiple digit-like protrusions on conjunctival surface ejected multiple worms on firm pressure on clinical examination. Samples of tissues that contained worms were surgically removed, fixed in ethanol and submitted to the parasitology and histopathology labs for morphological identification of worms and the nature of the tissue masses, respectively. The infestation was present only in young calves (< 3 months) and high-producing cows. Histopathology showed fibrovascular granulation tissue, containing a moderate to marked inflammatory infiltrate. Ivermectin treatment (200 μg/kg, SC, once) with and without surgical excision resolved the infestation. To the best of our knowledge, this is the first report of tissue invasion by T. gulosa.