Low Intensity Worming

Intestinal parasites (worms) are a significant ongoing problem in equine healthcare, in some cases causing colic, diarrhoea, weight loss and tail rubbing.

As a Practice we used to recommend strategic worming programmes based on manufacturers’ guidelines, however, following discussion with the experts at Moredun Research Institute, we now suggest previous advice was too simplistic and programmes should be tailored to individual horses/yards.

So instead of the blitz approach to worming previously advised, we now suggest a targeted approach to minimize drug use and more importantly minimize the chance of resistance developing.

There are no new types of wormers in the pipeline; therefore we need to be careful to ensure those we have currently remain effective.  There is well documented evidence of resistance to benzimidazoles (Panacur and Telmin) and further evidence of resistance to pyrantel (Strongid-P/Pyratape-P) in this country, and resistance in various parts of the world to all classes of worming drugs.

It is very important that we work to avoid these resistance issues. We therefore recommend that all owners in yard situations get together to devise a worming strategy.  We are happy to co-ordinate with other veterinary practices to avoid apparently conflicting advice. Ensure appropriate pasture management; don’t overgraze your pasture; guidelines are 1-1.5 acre per horse. Collecting dung as regularly as possible is still the best worm control.

Harrowing is not effective in our climate and can actually make the situation worse. We recommend all horses kept in a group should have a faecal worm egg count (FWEC) at least twice a year, preferably in spring and summer.  Ideally a representative number of the group should have blood taken to check for tapeworm antibodies, but since this will prove relatively expensive, it is still considered appropriate to worm all horses against tapeworm only with praziquantel twice a year, preferably in March and September.

Where anything other than a low count is found on FWEC, whether or not the horse should be wormed should be discussed with one of the vets as this will depend on the exact situation.  We also advise that all horses should be wormed in the autumn, preferably a month after the first frost, with either ivermectin or moxidectin.

Horses new to a yard, unless they have a well proven worming history, should have a FWEC or be wormed upon arrival with an appropriate wormer.  Again please consult one of the vets on which wormer is appropriate.  Such horses should not be turned out on “clean” pasture as any worms that survive the treatment will likely be resistant and the clean pasture will become colonised with resistant worms only.

At an appropriate interval (this will depend on the actual wormer used) the dung of treated horses should be checked again to ensure the treatment was effective.  It is likely some horses will never need treating, whilst others will require treatment every time.  Hence we advise a “yard pot” for FWEC and worming.  Contrary to the advice we used to give, it is better to stagger worming within a group of horses and not worm them all on the same day.

Also, as above, turning recently wormed horses out onto “clean” pasture is not advised. Please read and follow the manufacturer’s guidelines and precautions when using worming products, particularly regarding handler safety and correct disposal of packaging.

Anthelmintics can be very dangerous in the environment, for example to fish, and even small amounts left in packaging can be fatal to dogs. Please contact the practice if you require more information about a Health Plan for your yard (including vaccinations, health checks and/or teeth)