Factsheets - Sheep & Beef
The following fact sheets have been prepared by Anexa FVC Veterinarians as a guide to topics of interest. For specific information please contact your local vet.

Drench Checking

Drench Checking
By Lucy Scott, Veterinarian, Anexa Vets Raglan

Drench checking is a Fecal Egg Count (FEC) performed after drenching to confirm that a drench has worked. As the average lifecycle of strongyle worms is 21 days, we normally perform a drench check at day 10 post drenching.

Why 10 days you ask? Well the sheep/cattle will have taken in infective larvae from the pasture at this stage, but these larvae will not have had time to mature, breed and lay eggs. So the FEC should be zero. If it isn’t, we could have resistant parasites present, as any eggs found at this stage have been produced by worms not killed off by the drench.

To ensure that all the drenches you are using actually work on your farm, you should perform a drench check for every drench you use, at least once a year.

This coming spring we want to raise awareness of what a drench check does and why we do them so we are telling you early!

These are best done on young animals, as animals over 6 months old start to suppress the egg production of the parasites.

Please note: Long acting drenches for Barber’s Pole are not long acting for all worms so the tests are still relevant, but confirming long action efficacy for Barber’s Pole will require repeat sampling and larval cultures.

Collect a pooled sample; about 10 samples of the same size to fill the bag. Samples can be collected from the paddock as long as they are fresh! Get the samples to us as soon as possible and you should receive the results within 24-48 hours.


Date Added: Monday, 9th September 2019


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