Worms in cattle, buffalo, goats and sheep
Also called Gastrointestinal parasitism, roundworms
Worms in the stomach and gut are among the commonest causes of poor growth, anaemia and deaths in young animals and in goats and sheep. Heavy infections are often invisible until animals are thin and weak.
Cause and spread
- Cause
- Roundworms such as Haemonchus (barber's pole worm) and Teladorsagia in the stomachs of small ruminants, and many other gut worms.
- How it spreads
- Animals swallow infective larvae on pasture, laid as eggs in the dung of other animals. A single Haemonchus female can lay up to 10,000 eggs a day.
Signs to watch for
- Poor growth, weight loss and rough coat
- Anaemia with pale gums and eyelids
- Swelling under the jaw (bottle jaw)
- Diarrhoea in some worm types
- Lower milk yield, and deaths in heavy infections, especially in kids and lambs
Many diseases look alike. Only a laboratory test can tell them apart, so please see a veterinarian for any sick animal.
How it is diagnosed
Egg counts in dung show the worm burden. A faecal egg count (McMaster) gives eggs per gram, and the same count before and 14 days after a dewormer shows whether the dewormer worked; counts that stay high suggest resistance.
- Usually the first testFaecal FlotationFinds worm eggs in dung.
- Usually the first testHerd Parasite Check (panel)Flotation, egg count and fluke sedimentation together, for the whole herd or flock.
- Confirms the diseaseFaecal Egg Count (McMaster)Counts eggs per gram, to judge how heavy the infection is and whether deworming worked.
- Supports the diagnosisComplete Blood Count (CBC)Shows anaemia from blood-sucking worms.
Prevention and control
- Count eggs in dung before treating, and again about 14 days after, to check that the dewormer worked
- Young animals usually have much higher egg counts than adults, so interpret results by age
- Ask your veterinarian for a worm-control plan for your herd or flock
Where this information comes from
- Common Gastrointestinal Parasites of Small Ruminants · Merck Veterinary Manual
- Parasitology in Veterinary Practice · Merck Veterinary Manual
General information for animal owners and veterinarians, last checked October 2026. It does not replace the advice of your veterinarian, who should decide which tests and treatment your animal needs.