Trichostrongylus axei, the stomach hair worm, is a trichostrongylid parasite infecting a variety of hosts, including sheep, goats, cattle, and horses. Human infections have been described as well. The environmental life cycle is similar to cyathostomins Larval Cyathostominosis in Horses Larval cyathostominosis is a clinical syndrome caused by mass emergence of encysted cyathostomin larvae from the large intestinal walls. It is characterized by acute, generalized typhlocolitis... read more , with the third stage larva being the infective stage. Once ingested, the larvae penetrate the gastric mucosa and develop into adult worms and emerge into the gastric lumen. Egg production begins 3–4 weeks after infection.
The parasite is seldom encountered in domestic horses and is not considered a primary parasitic pathogen.
Although no recent anthelmintic efficacy studies exist, T axei is expected to be susceptible to macrocyclic lactone (ivermectin or moxidectin) or benzimidazole (fenbendazole or oxibendazole) treatment. Benzimidazole resistance has been reported in T axei infecting sheep, so this could also occur in horses.
Also see pet health content regarding small stomach worms in horses Small Stomach Worm (Trichostrongylus) Numerous parasites can infect the digestive system of horses (see Table: Common Gastrointestinal Parasites of Horses). The most common ones are described in the following text. The stomach worms... read more .