Best practice treatment of cattle parasites

This page explains how to treat cattle parasites safely and effectively. It also outlines the main types of wormers, how to use them and the best practice steps to follow for each method of administration.

Anthelmintics (wormers) are used to treat and prevent parasite infections – roundworm, tapeworm, lungworm and liver fluke.

These products fall into the following groups:

• Group 1: (White, BZ) Benzimidazoles
• Group 2: (Yellow, LV) Levamisole (Imidazothiazoles)
• Group 3: (Clear, ML) Macrocyclic lactones, including avermectins and milbemycins
• Group 4: (Orange, AD) Amino acetonitrile derivatives
• Group 5: (Purple, SI) Spiroindoles

The parasite control guide also covers combination products, flukicides and synthetic pyrethroids for cattle, as well as combination products, narrow spectrum, injectables for sheep scab, plunge dips and pour-ons for sheep.

Regardless of the administration used, always read the manufacturer’s instructions carefully.

Pay particular attention to:

• Class of stock the drug is recommended for and any limitations regarding use
• Dose rate and any recommended increases to deal with different parasite species or developmental stages
• Meat withholding period before slaughter
• Individual liveweight assessment, using scales or a weigh band, to avoid under- or overdosing

Best practice:

• Dose accurately against individual liveweights
• For groups of well-matched cattle, you can weigh a sample of animals and treat the group accordingly
• Make sure wormers are stored correctly, away from direct sunlight and extreme temperatures
• Check the use-by date and, once open, use within the time shown on the packaging
• Some products need to be shaken well before use
• Make sure equipment is suitable and calibrated to deliver the correct dose
• After use, rinse, clean and dry equipment before storage

These should be applied along the length of the flattest part of the animal’s back, from the withers to the tail head.

In general, animals should not be treated when the hair is wet or if rain is expected within two hours of treatment. However, some products are waterproof and can be used on wet animals.

Avoid areas with damaged skin, mud or manure.

Injectables should be given according to the manufacturer’s instructions at the recommended injection site.

Best practice:

• Always use a clean, sterile syringe and needle
• If using a multiple injection gun, disinfect the needle between injections, e.g. with an automatic sterilisation system
• If the injection site is dirty, clean the skin and swab with an alcohol wipe or cotton wool

Before injecting:

• Check the expiry date
• Read the product instructions carefully
• Some products need to be shaken before use

Administration:

• Use the correct needle size for the animal and injection site
• Make sure the animal is adequately restrained
• For subcutaneous injections, raise a fold of skin at the injection site (mainly neck, but some are ear) and inject into the space created (Figure 1)
• If a large dose is needed, consider splitting the dose between two injection sites
• After the injection, briefly massage the site to help distribute the product
• Dispose of the needle and syringe in appropriate clinical waste and sharps containers

Figure 1. Injecting into subcutaneous tissue

These wormers are administered orally using product-specific equipment.

Administration:

• Follow the manufacturer’s instructions to make sure the boluses are delivered over the back of the tongue so they can be swallowed
• Avoid using excess force as it may damage the throat
• Do not depress the plunger until the bolus is correctly positioned

It’s important that the animal stays as calm as possible and can swallow.

Keep the head and neck in a straight line. Administration becomes difficult and unsafe if the neck is twisted and the animal is fighting you.

Figure 2. Administering an oral bolus to a restrained cow using a bolus gun

Oral drenching guns are designed to deliver the treatment towards the back of the mouth over the tongue so the entire dose is swallowed at once to optimise efficacy.

Best practice:

• Make sure animals are properly restrained, with their head held up
• Slide the nozzle of the dosing gun into the side of the mouth and over the tongue
• Drenching equipment must be correctly calibrated and in good working order
• Calibrate the gun just before treatment by delivering two or more doses into a graduated measuring cylinder

Faulty equipment or dosing too quickly may mean that the barrel of the gun does not fill properly or that the liquid is full of bubbles, which may lead to underdosing.

Products may be compromised by incorrect storage.

Wormers should be stored securely, away from direct sunlight, at 4–25°C.

Check the use-by date and, once open, use within the time shown on the packaging. Some products need shaking before use.

Products that combine a wormer and flukicide can seem like a good option for broad-spectrum control with a single administration.

However, they should only be used when:

• Cattle need treatment for both worms and fluke
• The wormer is effective against the stages of the target worms present
• Any persistent activity of the wormer has been assessed
• The flukicide has the appropriate activity for the stages of liver fluke likely to be present

For help selecting and administering the right product, consult your vet or SQP/RAMA.

• Using medicines responsibly
• Worm control in sheep
• Liver fluke control in grazing livestock