Animal health: Acaricide resistance

The chemicals used to treat cattle against ticks are called acaricides. When cattle are dipped, the ticks fall off or die.

Animal health: Acaricide resistance
Acaricides, chemicals used to treat cattle against ticks, do not always work as they should.
Photo: FW Archive

After this process, the cattle emerge free of ticks. You are likely to have a problem if you still find many ticks on the cattle after dipping.

This is a sign that the acaricide is not working as well as it should and that the ticks may have developed resistance to it. This occurs if the same acaricide is used too often or for too long.

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If using a plunge dip, make sure that you mix the right quantity of dip for the size of the tank.

An animal health technician can assist with measuring the strength of the dip. Finding many ticks on your cattle after dipping may not always indicate acaricide resistance.

The dip, for example, may not have been used at the correct strength. To avoid this, check the instructions and ensure that you follow them properly.

If you are using the dip correctly and its strength is as it should be, the problem may be acaricide resistance. Your animal health technician can assist by taking some of the ticks from the cattle after dipping and sending them to the laboratory to test for resistance.

The results will then determine whether acaricide resistance is a problem in the area. If this is the case, the results will be able to indicate the types of acaricides to use.

There are a number of ways to avoid ticks from becoming resistant to acaricides:

  • Get advice from your animal health technician or vet on which acaricides are best to use in your area, as well as how to use them.
  • Use strategic rather than intensive dipping.
  • Use dips of the correct dilution.
  • Do not use homemade dips.

For further information, contact your animal health technician or state veterinarian.
Source: Directorate Communication Services (department of agriculture) in co-operation with ARC-Onderstepoort Veterinary Institute