Small stomach and intestinal worm
Several different species infect goats, but T. axei, which can infect other species as well as man,
and T. colubriformis are the most common.
Oocytes quickly develop into embryos at a temperature of 70° to 80° F (22-27° C).
Embryonated eggs are very resistant to drying and temperature extremes.
First stage larva hatch and live free in the soil.
Second stage larva emerge from the first stage cuticle.
Both the first and second stage larvae have a rhabditiform esophagus type.
Infective third stage larvae develop 16 to 20 hours after the egg was laid.
The third stage is resistant to drying and temperature due to the retained protective cuticle.
Infective third stage larvae migrate less than an inch up wet blades of grass.
Infective larvae are swallowed with forage and migrate through the four stomachs.
Larvae shed their cuticle in the abomasum.
T. colubriformis migrates to the small intestine.
The larvae work their way into the lining of the stomach or intestinal wall
where they molt to the fourth stage.
In about 4 days they leave the wall to mature.
Adults start laying eggs about 3 weeks after infection.
Oocyte: 80 to 85 µm long,
40 microm wide, developed to the 16 to 32 cell stage when passed with feces.
The irritation to the lining of the intestine by the larva cause the main problems.
Severe infections in young goats can result weakness and death.
The main symptom is black colored diarrhea called "black scours."
The adult worm is not a heavy egg layer, so a heavy load of worms may show
only a small number of eggs on a fecal count.
If cured, the goat can become immune to future infections of (span class = "ital">T. axei.