DEPARTMENT: AGRICULTURE

EXTERNAL

PARASITES OF CATTLE



Jenny Turton


EXTERNAL PARASITES OF CATTLE

External parasites live on the skin of cattle or visit them to feed

The most important groups are flies and ticks

Lice and mites are usually not very important, but do occur occasionally.

Most of these parasites can be seen with the eye alone, although for mites you need to look through a microscope

Why are external parasites important?

Some are just a nuisance to the animals

Some cause skin and eye irritation and damage, which can lead to bacterial infection and fly maggot attack

Some create large wounds

Others suck blood causing the animals to become weak

Some can spread diseases between animals

Some can cause disease through poisonous bites (toxins)

All of this can result in decreased production and even death


FLIES

Flies are most active in the rainy season and warm months

There are many types of flies

Some are biting flies, others are important because they lay eggs on animals, while others irritate the animals

Biting flies

There are many biting flies and these include blackflies, biting midges, mosquitoes, stable flies, horseflies and tsetse flies

Some flies such as black flies, mosquitoes and midges attack animals in swarms

These flies suck blood and cause irritation, painful bites and blood loss

Many of these can also spread diseases among animals, such as gallsickness (horseflies); three-day stiffsickness (biting midges and mosquitoes); lumpy-skin disease (biting flies); Rift Valley fever (mosquitoes); nagana (tsetse flies); pinkeye (face flies)

Flies which cause fly strike

Other flies (blowflies and screw-worm flies) are important because they lay their eggs on animals

The eggs hatch into larvae (maggots) and can cause severe injuries to animals

The condition caused by maggots living on animals is called fly strike

Tick bites and cuts can become infested with blowflies or screwworm. This can lead to severe wounds and even death

Treatment of fly strike

Clip and clean coat around the area affected, remove maggots and treat with insecticidal cream, powder or spray. The animals may need treatment with antibiotics

Control of flies

Practise good stable and kraal hygiene (clean regularly)

Remove manure to large bins to restrict fly breeding and to make compost

Drain damp areas to stop breeding of mosquitoes and biting midges

Use dips, sprays and treat wounds to prevent fly and strike problems

Immediately treat skin wounds so that strike does not occur

TICKS

There are many different types of ticks

Ticks are usually most active during the warmer and wetter parts of the year

Ticks suck blood from animals, and large tick numbers can lead to blood loss and weakness

Some ticks have long mouthparts and can cause severe skin damage, which can lead to fly strike and bacterial infection

Ticks can also spread diseases such as heartwater (bont ticks), redwater (blue ticks), gallsickness (blue ticks) and corridor disease (brown ticks) among animals

Some ticks (Karoo paralysis tick, glossy brown tick) can cause paralysis as a result of the toxins they produce

Other ticks (small smooth bontlegged tick) can cause sweating sickness as a result of the toxins they produce

Treatment of tick damage

Clean the wound, treat with an insecticidal-disinfectant combination to heal the wound and to keep flies away. Antibiotics may be needed

Control of ticks

Control is by acaricides which are chemicals that kill ticks or prevent their attachment. They can be used as sprays (handsprays or race-sprays), dips, pour-ons, spot treatment or injectable drugs

Some breeds of cattle are more resistant to ticks and tick-borne diseases

It is best to get advice from your state veterinarian or animal health technician on control methods for ticks in your area


MITES

Mites are very small, and can usually not be seen with the naked eye

Mites live on the animal for the entire lifecycle and are spread among animals by close contact

They cause skin irritation, which leads to rubbing, scratching and hair loss; this is called mange

Irritation from mites is usually seen on the head, neck and legs. It is associated with crowded conditions and poor husbandry

There are different types of mange, depending on the type of mite involved: sarcoptic mange, demodectic mange, chorioptic mange and psoroptic mange

Skin disease with irritation, scratching, rubbing and biting should always make one suspect mange or lice

Because it is impossible or very difficult to see the mites with the naked eye, diagnosis is by skin scrapings and looking for mites under the microscope

Control and treatment of mites

Control and treatment is by acaricides, which may be injectable drugs such as ivermectin, handsprays or dips

Sarcoptic mange may require repeat treatments


LICE

Lice are wingless. They live exclusively on the skin and cannot survive for long periods off the animals

Lice can be seen by parting the hair; you can see them moving and their eggs may be attached to the hair

Lice are very specific to the type of animal and will not spread to other animal species. They are spread by contact among animals of the same species

There are sucking and biting (chewing) lice

Heavy lice infestations can cause irritation and distress. Animals rub and lick themselves, and damage their hides

Sucking lice can also cause weakness from blood loss

Lice are usually associated with unhealthy livestock in crowded conditions

Often heavy lice infestations are secondary to some other disease problem, largely because sick animals do not groom themselves

Control of lice

Control by insecticides (dusts, pour-ons, spot treatment, handsprays, dips)


For further information contact your animal health
technician or veterinarian
or
Animal Health for Developing Farmers

ARC-Onderstepoort Veterinary Institute
Private Bag X05, Onderstepoort 0110

This publication is available on the web at : www.nda.agric.za/publications




Information provided by
Animal Health for Developing Farmers
ARC-Onderstepoort Veterinary Institute
Private Bag X05, Onderstepoort 0110

2001

Compiled by Directorate Communication, Department of Agriculture
in cooperation with the ARC_Onderstepoort Veterinary Institute

Printed and published by Department of Agriculture
and obtainable from the Resource Centre, Directorate Communication
Private Bag X144, Pretoria, 0001 South Africa