Clinical co-parasitic infections in a cat imported from Thailand

Animal welfare benefits associated with international pet rescue and adoption are somewhat offset by increased potential for introduction and spread of foreign pathogens. This report describes clinical and parasitological findings in an adopted stray cat imported from Thailand. The cat was presented to a veterinary clinic for veterinary care 5 d after arrival in Canada. The cat was dewormed and passed a large mass of tapeworms on the following day. Fecal and blood samples were submitted to Diagnostic Services at the Atlantic Veterinary College (Charlottetown, Prince Edward Island). Eggs of Mammomonogamus spp. and Spirometra spp., oocysts of Cystoisospora spp., and a metastrongyloid 1st-stage nematode larva (L₁) were seen on microscopic examination of fecal flotation. Additional L₁ recovered using the Baermann technique were molecularly characterized using small subunit rRNA-PCR, and DNA sequencing identified the larvae as Oslerus rostratus. The cat was treated with a 2-day course of milbemycin oxime (10.7 mg/kg) and praziquantel (26.8 mg/kg), followed 5 d later by a 5-day course of fenbendazole (50 mg/kg). Posttreatment fecal examinations showed no evidence of parasitic infection. The cat resumed shedding Spirometra spp. eggs 40 d later and was given a second 2-day course of milbemycin oxime and praziquantel. Fecal examinations conducted at 7 and 35 d after treatment did not reveal any parasitic eggs or cysts. The occurrences of O. rostratus and Mammomonogamus spp. are reported and diagnosed for the first time in Canada. The risk of foreign pathogen spread into a new geographical region was minimized by timely diagnoses, appropriate veterinary care, and the cooperation of conscientious owners via biocontainment by isolation of the cat and proper feces disposal. Key clinical message: Knowing the clinical and travel history of an animal is critical for making an accurate diagnosis. Molecular confirmatory testing is valuable when diagnosing parasitic infections with similar morphologies.