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Parasite Treatment

Penbode Farm Vets offer advice and treatment to help identify and reduce parasitic issues in your herd.


The most common roundworms are ostertagia ostertagi, which live in the abomasum, and cooperia oncophora, which inhabit the small intestine.

Clinical disease – loss of appetite, scouring and poor condition – is generally only seen in young calves during their first grazing season when control has been inadequate.

Cattle do acquire immunity when exposed to roundworms, but it can take up to two grazing seasons.

Top tips for control

1. Identify risk

a. Younger cattle are highest risk

b. Permanent grazed pasture is highest risk

c. Larval worms accumulate throughout the grazing season

d. Young cattle not treated at housing are at risk later in the winter

2. Treat appropriately

a. Wormers should be targeted at individuals or groups at appropriate times

b. Strategic treatments can be used

c. Treatment at housing can minimise risk later in winter

3. Avoid resistance

a. Use wormers correctly


Lungworm is an economically important parasite infection of the bovine respiratory tract caused by the nematode dictyocaulus viviparus.

Symptoms are most commonly seen in first-year grazing cattle in late summer and autumn but can occur earlier in the year and in older cattle.

The most characteristic clinical sign of lungworm infection is widespread coughing within the herd. Death can occur in heavy infections.

Top tips for control

1. Identify Risk

a. Lungworm outbreaks are unpredictable but more common in wetter areas

b. Suspect infection if coughing at pasture

c. Exposure normally develops resistance to reinfection

d. Bought in animals may bring in lungworm

2. Treat appropriately

a. Routine vaccination should be considered for calves born into herds with an issue

b. Strategic use of wormers can be used to control

c. Severely affected animals may require extra supportive treatment

3. Plan ahead

a. Work out a control strategy to prevent infection

Liver Fluke

Liver fluke fasciola hepatica is also known as fasciolosis. Cattle typically develop chronic disease and classically show loss of weight and condition and may become anaemic.

Severity of disease depends on the number of parasites present in the animal.

Livestock become infected by ingesting the infective stage from contaminated grass and vegetation. These hatch in the small intestine and migrate across the gut wall directly into the liver.

The migrating flukes cause liver damage, destruction of tissue and haemorrhage. The greater the number of fluke present, the more severe the liver damage and the more serious the disease.

Cattle infected with lower fluke numbers may show sub-clinical effects. In dairy cattle, this manifests as reduced milk yield, changes in milk quality and can also affect fertility.

In younger stock, sub-clinical infection may result in reduced feed conversion ratios, poor growth and reduced carcase value, including liver condemnation.

Top tips for control

1. Identify risk

a. Co-grazing with sheep increases the risk to cattle

b. Buying in animals may bring fluke onto previously clean pasture

c. Long grazing seasons increase risk

2. Treat appropriately

a. Consider the five Rs


b. Different products work against different life stages

c. Be aware of licensed products in milking cows

ii. Treat the RIGHT ANIMAL

iii. Treat at the RIGHT TIME

iv. Dose at the RIGHT RATE

v. Administer in the RIGHT WAY

b. Quarantine incoming stock

c. Be prepared through plan management and control

Ectoparasites – lice, mites and insects

Cattle are affected by a range of arthropod ectoparasites and nuisance pests, which can cause significant production losses and severely compromise animal welfare.

Lice are grouped into chewing and sucking lice. Control generally coincides with housing and can be combined with other parasite control.

Mites cause mange in cattle, the most common being chorioptic mange. Control via chemical product often has to be combined with moving housing to break the life cycle.

Ticks only spend a small amount of time on the cow but can transmit other diseases. There is no licensed tick control product for cattle in the UK.

Flies are collectively termed nuisance flies but can also transmit other diseases. Fly control is often based around insecticide usage combined with methods of deterring flies and keeping cattle away from breeding grounds where possible

Further information on all parasites can be found on the COWS website:

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