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Internal Parasites

Internal parasites (endoparasites) of cattle affect the gut, lungs and liver. Roundworms affect the abomasum (4th stomach), intestine, lungs and liver. Tapeworms parasitise the intestines. Flukes parasitise the liver and rumen.

Endoparasites are normally diagnosed by faecal egg counts. Laboratory examination can determine not only the type of infection present but can also determine the concentration of eggs which provides information about the number of worms a cow is infested with.


Gastrointestinal parasites are typically a problem of young stock which are most vulnerable from weaning until about 15 months old they are vulnerable.

The main roundworm culprits, Ostertagia, Trichostrongylus and Cooperia are widespread in cattle, particularly where there is reasonable rainfall and grass growth. Peak pasture loads are during warm and wet periods, notably autumn and spring. Mature worms live in the cow’s gut, and lay 1000s of eggs which pass onto the pasture. These eggs hatch into larvae, become infectious, and can be ingested to restart the cycle.

Adult cows generally carry very light worm burdens and shed few eggs. However prior to calving, they may be more vulnerable, as their immunity wanes and pasture contamination may rise. A number of studies with new anthelminitics suggest there is an economic advantage to worming dry cows, particularly close to calving.

When it comes to controlling worms, there is no substitute for a good oral drenching program. Good drench programs attempt to not only keep the animals (calves) from building up huge worm burdens; they also help create clean pasture for the animals to go on to.

There are many options to consider with a drenching program. Make sure you see us before deciding on what to do, as it is too easy to choose a plan or a product which wastes money and is ineffective. 


Lungworm infections are only significant in young cattle. Infective Dictyocaulus larvae are picked up off the pasture, and swallowed. They penetrate the gut but then travel to the lungs, where they grow to adulthood. Adult worms lay eggs in the lungs, which are coughed up, swallowed, hatch and are passed out in the faeces so the cycle continues…

Infection results in a productive “foreign body” cough, which is unresponsive to antibiotics. Severe infections can lead to breathing difficulty and even death. Regular anthelmintic treatment will aid in the management of lungworm.

Liver Fluke

The common liver fluke, Fasciola hepatica is a parasite of all grazing ruminants. It damages the which can lead to severe liver disease and anaemia. As a result there can be chronic wasting, poor production and death.

Liver fluke uses an aquatic snail as part of its life cycle so disease is often confined to the wetter areas, or farms with unfenced ponds, streams or swampy areas. Diagnosis is based on Faecal Egg Count and blood tests.

As summer and autumn is peak season for picking up fluke, a good drench in the Autumn will clean out infections, and pastures will be very safe in the winter. There are very good treatments are available for liver fluke.

Ask us whether we have seen any liver fluke in our local area.

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About Us

Local farmers, associated rural communities and Te Puke town people have supported Te Puke Vet Centre for over 50 years. During those years scores of receptionists, nurses and vets have lived and enjoyed the benefits of this great town and area. It is very important for Te Puke Vets that we are strongly integrated with the local community and as part of that we are proud to support many local schools, sports clubs, service organisations and community events.