Stomach hair worm

(Trichostrongylus axei)

Trichostrongylus axei is a common parasite in the abomasum (fourth stomach) of cattle, sheep, goats, and deer, and also in the stomach of the horse and man.

Stomach hair worm is commonly found in association with the small brown stomach worm (Ostertagia ostertagi) in temperate districts. These worms in a mixed infection, intensify the damage caused by each one individually and facilitate the establishment of each other. Young steers and heifers can suffer damaging infections during winter when nutrition is poor. In warmer wetter districts they often occur in association with barber’s pole worms (Haemonchus placei). Infections may persist at low levels in cattle up to 18 months of age.

Figure 1. Eggs of Trichostrongylus spp are elliptical and have a thin shell. Image courtesy of the National Centre for Veterinary Parasitology, ncvetp.org

Stomach hair worms are small, hair-like worms tapered at one end. Males are 3–4 mm long and the females are 4–5 mm long, and not easily seen at post mortem. The adult female typically lays 100–200 eggs per day.

Resistance to drench treatments has been reported.

Further ecological information on worms and their control:

  • Roundworm life cycle and life stages
  • Stomach hair worms have a typical roundworm life cycle except that the early fourth (L4) pre-adult stage larvae may embed into the mucosal layer of the abomasum wall in late spring. Larvae ingested at the end of the summer can remain arrested inside the host over the winter and resume development next spring. Eggs on pasture containing fully formed embryos are able to delay hatching for up to fifteen months if environmental conditions become unfavourable. Infective larvae are also highly resistant to dryness. The pre-patent period is about 15 days.
  • Climate factors contributing to paddock contamination with worms
  • Pasture management to reduce exposure to worms
  • Cost of roundworms

Location in cattle

Mucosa of the abomasum.

Figure 2. The males of species of Trichostrongylus have short and pointed reproductive structures called spicules. Image courtesy of the National Centre for Veterinary Parasitology, ncvetp.org

Signs

The small numbers usually present are relatively harmless but in heavy infections signs are indicative of severe protein loss and consist of lack of appetite, a protracted and debilitating profuse watery diarrhoea that is often green in colour, rapid weight loss, and death. Disease may appear quite suddenly in heifers in early winter and deaths may occur while cattle are in good condition and before diarrhoea is noted.

Signs of worms

Diagnosis

The only accurate way to confirm worm infections before productivity losses have occurred is to conduct a worm egg count (WEC). Also request a larval culture or DNA test. The results allow you to determine the need for a drench or management action.

Worm egg counting does not always correlate well with the number of adult worms present for cattle over 9 months of age. For this age group observation of physical signs such as body condition scoring and monitoring target growth weights are good additional indicators to diagnose worm infections.

If visual signs of worms are present in cattle then significant production loss has already occurred. Also, these signs can occur with other parasites and diseases.

Figure 3. Anterior end of an adult species of Trichostrongylus showing the excretory pore, an indentation on the left-hand side. Image courtesy of the National Centre for Veterinary Parasitology, ncvetp.org

Treatment

Your decision can be assisted by using the how to decide which animals to treat section and the WormBoss cattle products search guide for your region, a simple tool that considers some of the points above. It is also important to consider cattle management options, as simply removing the affected mob to a less wormy pasture will reduce the re-infection risk.

You can also review the chemical pages on this site to find out specific information about drenches, including their drench active, drench group, how they are administered, which worms they treat, resistance status, safety information and how they work.

The negative impact of this worm can also be reduced through using one of the integrated annual worm control programs that have been specifically developed for different regions across Australia.