Tritrichomonas foetus and Giardia duodenalis are possible causes of diarrhea in cats. T foetus infection results in chronic diarrhea and often affects cats from shelters or catteries. The trophozoite stage of T foetus has previously been described in cats, but the pseudocyst stage is typically found only in bovine animals. Giardia duodenalis infection is more variable in cats. The organisms are known to coinfect cats.
This case report described 2 littermate cats with a coinfection of G duodenalis and T foetus in the pseudocyst stage. One littermate was originally presented for diarrhea. After an ascarid infection was confirmed, both littermates were treated orally with milbemycin and praziquantel. As diarrhea persisted in the affected cat, coproantigen testing was performed. Results were positive for Giardia spp, and the kitten was treated with fenbendazole for 5 days. Ongoing diarrhea in the affected kitten was treated with a 10-day course of spiramycin and metronidazole. Although clinical signs briefly resolved, both cats developed diarrhea a few days later.
Fecal smears stained with Lugol solution and Giemsa stain identified Giardia spp cysts and trophozoites as well as unidentified drop-shaped elements, which were discovered to be T foetus pseudocysts. PCR analysis confirmed T foetus infection. The patients were treated with ronidazole for 14 days, and clinical signs resolved.