Ollulanus tricuspis

Ollulanus tricuspis, a common parasitic Trichostrongyle nematode of the cat stomach, is also found in the fox and occasionally, the pig[1]. It lives in the stomach and the first inch or so of the small intestine[2].

Adult worms live in the stomach and may burrow into the gastric mucosa. The eggs hatch while in the female and develop to the infectious third-stage larvae (L3), which is released into the lumen of the stomach. The L3 may continue its development to the L4 and adult stage in the same cat or it may be carried into the environment in parasite-induced vomitus. The L3s may live in the vomitus for up to 12 days. If the L3s in the vomitus are ingested by a suitable host they will develop to adults in the stomach. The prepatent period (the time from when the L3s enter the host till the next generation of L3s is born) is about 33 to 37 days. Larvae which pass into the intestine die and are digested.

In cats, Ollulanus spp worms cause vomiting, anorexia, diarrhoea and weight loss[3]. Physical examination may be normal or reveal evidence of weight loss. Gastritis and pancreatitis may be seen[4]. In two related Persian cats, gastric adenocarcinoma and chronic gastritis has been implied as possibly induced by the presence of Ollulanus spp nematodes[5].

Physaloptera spp stomach worms can also cause similar signs that are typically more chronic, but typically produce melena and anaemia in affected cats[6].

Diagnosis is based on isolation of Ollulanus spp eggs in feces or isolation of adults from biopsy of the stomach.

This nematode is susceptible to treatment with fenbendazole and most synthetic ivermectins including selamectin[7].



  1. ↑ Bell AG (1984) N Z Vet J 32(6):85-87
  2. ↑ Cecchi R et al (2006) Demonstration of Ollulanus tricuspis in the stomach of domestic cats by biopsy. J Comp Pathol 134(4):374-377
  3. ↑ Hargis AM et al (1983) Ollulanus tricuspis found by fecal flotation in a cat with diarrhea. J Am Vet Med Assoc 182(10):1122-1123
  4. ↑ van der Linde-Sipman JS et al (1992) 3 cases of hypertrophic gastritis associated with a Ollulanus tricuspis infection in cats. Tijdschr Diergeneeskd 117(24):727-729
  5. ↑ Dennis MM et al (2006) Gastric adenocarcinoma and chronic gastritis in two related Persian cats. Vet Pathol 43(3):358-362
  6. ↑ Norsworthy, DG (2006) Stomach worms. In: The Feline Patient, 3rd Ed, pp:303-304
  7. ↑ Hall, JA (2000) Diseases of the stomach. In: Ettinger, SJ & Feldman, EC, Textbook of veterinary internal medicine. 5th edition. WB Saunders, Philadelphia. pp:1154-1182

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