- Throughout their lives, goats are very susceptible to worms in their stomach and intestines.
- Big worm burdens cause ill-thrift, weight loss, diarrhoea and even anaemia and death.
- Anthelmintics can get rid of worms, but it is important to give the correct type of anthelmintic, give the correct dose and drench at appropriate intervals.
- Giving too little drench is ineffective and will encourage the worms to become resistant to the drench.
- Giving too much can cause poisoning, especially if selenium has been added to the drench.
- A degree of worm control can be achieved by pasture management, as well as by giving effective anthelmintic drenches when required.
- Grazing goats with cattle or horses (which don't share the same worms) can help prevent the build-up of worm larvae on pasture.
- Grazing long pasture can help control worms because larvae tend to be concentrated at the base of the sward.
- Feeding browse is good too because shrubs and trees are generally not contaminated by faeces that might contain worm eggs and larvae.
- Cutting grass and carrying it to goats from faeces-free areas might be laborious but it helps keep worm burdens down (as long as you don’t give too much at once and cause digestive problems!).
- Efficient drenching involves giving an effective anthelmintic at strategic intervals to keep worm burdens in goats down to a level that is doing no harm.
- Read the instructions on the drench container, and give each goat the correct dose for its weight.
- If commercial animal scales are not available, then use bathroom scales.
- Weigh yourself, then pick up a goat and weigh yourself and the goat - the difference is the goat's weight.
- Do this for a representative number of animals to make sure you know the weight of each goat before you drench it.
Faecal egg counts
- If a drench is effective, egg counts will be zero in faecal samples taken from the goats 7 to 10 days later.
- Your vet can arrange for tests of faecal samples taken at that time to confirm nil egg counts.
- If egg counts are not zero, your drenching was not effective.
- The dose rate may have been wrong or the drenching technique (eg the drench gun) may have been faulty.
- Alternatively, the worms may be resistant to the drench used, in which case you will need your vet's help to select an effective drench in future.
- Drench resistance means that some or all of the worms in the goats are not being removed by the drench used.
- Once you have drench-resistant worms in pasture and in livestock on your farm, it is very difficult or impossible to get rid of them, and you must change to an effective drench.
- It is wise to test for drench effectiveness from time to time (as described above), to maintain good worm control.
Withholding times in dairy goats
- In dairy and meat goats, withholding times must be observed, and these are clearly shown on the anthelmintic label.
- The withholding time is the time that you should allow to elapse before milk or meat from that animal is used for human consumption.
- For some of the long-acting third-generation drenches, the withholding time is remarkably long, so you have to take this into account when planning the drenching programme.
- For example, Ivomec should not be used at all during lactation or in the last 28 days before kidding if the milk is to be drunk by humans.
- It can seem complicated - which is why it is important to get advice from a veterinarian if you have any doubt about choosing a drench for dairy or meat goats that is effective in controlling worm burdens.
- Written by: Dr Clive Dalton