The gold standard of internal parasite management is to float manures to identify parasites, and then use specific wormers to combat the identified parasites in the manures. Even then, floats only show adult parasites that are making eggs, and not larval stage intestinal worms.
Our preference is to worm all horses in the A months (April and August) using moxidectin (Equest), or doses over 5 days of fenbendazole (Panacur), because of the increasing resistance of worms to ivermectin in our region, and then to float manures in other months only the specific horses that are showing symptoms of parasite burden (please see our previous blog post on wormers) in conjunction with all of the methods outlined below.
Symptoms of intestinal parasites include:
loss of appetite
There are many cheap, or even free, aspects of husbandry that help to reduce parasite burdens in your horses.
If you have the time, collect manures daily and compost. Any worm eggs are removed with the manures, preventing ingestion. Composting manures will bring the temperature up to a heat that will kill worm eggs. You can then use this compost to feed shade trees in your paddock. Aside from incidental exercise and vitamin D for yourself, it also gives you an opportunity to identify problematic weeds in your pasture.
“We’ve always considered roundworm (ascarid) eggs the most resistant of all parasite eggs, able to withstand extremes in heat and drying,” adds Andrew S. Peregrine, BVMS, PhD, DVM, Dipl. EVPC, ACVM, associate professor in the Department of Pathobiology at the University of Guelph’s Ontario Veterinary College. “To discover that the heat of composting can kill these eggs in a relatively short time (four or five days) is fantastic, because an even shorter time would kill strongyle eggs.”
Here is a simple one. We feed every horse a cup of oats each day. While oats are a great feed for horses, our primary reason is that native birds - mostly parrots, will descend on the paddock throughout the day in search of oats and spread the manures out, exposing the eggs to UV. Dung beetles which are active in warmer months, also help to manage manures,
There are tools out there for paddock scraping, but a farmgate attached to your tow-ball will do the same job. Please keep in mind that this is only useful in summer or in winter, when UV and extreme cold exposure will kill worm eggs. In warm, moist weather you may just be spreading parasites further around your pasture.
Ideally, you will harrow (spread manure to expose parasite eggs to UV) and then rest the paddock for a few weeks so eggs cannot be ingested.
If you have the capacity to do so, resting paddocks will help to break the worm cycle. The length of time required will vary by season. In very hot or very cold conditions, a month will be long enough, particularly in conjunction with harrowing, but in moist and humid conditions, parasite eggs can survive longer in the pasture, in which case, manure collection is preferable.
Float your own poos
The McMasters method of fecal floating is not difficult, or expensive. With the appropriate equipment you can do this yourself. In a nutshell, you collect manure, take a small amount and mix into a saline solution. You put the solution into the McMaster's slide and then count the eggs in each panel of the slide. This will give you an indication of how much of a parasite burden (if any) that your horse has and which parasites are present. Here is guide. If you have many horses on your property it is much more cost effective to do this yourself than to send samples to a lab or to your vet.
A recent study of probiotic use in foals showed that:
The use of probiotics in horses to affect changes in gut physiology is expanding rapidly. Typically, probiotic administration is aimed at improving gastrointestinal health through alteration of the host microbiome. However, administration of these novel bacterial strains may have wider-reaching effects. Internal parasites pose a risk to the health of horses. The principle method of parasite management is targeted anthelmintic administration, although increased parasite resistance is of concern. Data from studies in humans and production animals has indicated that certain probiotics may interfere with the physiology of parasites, reducing overall parasite load.
This study showed that foals administered probiotics had lower parasite burdens than foals that had no intervention.
Young horses are at particular risk from parasite burden
We have two prebiotic/probiotic supplements that can improve gut health. Using Bio Mos and Yea Sacc can help to prevent and manage gastro-intestinal ulcers, improve hoof health, avoid scours and malodourous manures, and also help with parasite management. That's a pretty good deal at 10g per day, particularly as they are both natural products that promote overall health, rather than chemical/pharmaceutical treatments.
There is no one silver bullet to manage parasites for our horses - given the increasing incidence of resistance - just administering wormers is not going to be enough. A combination of managing manures through collection, harrowing and paddock rotation, monitoring parasite burden through floats, supplementing to improve gut health and immune function - as well as the use of appropriate wormers will ensure you have gastro-intestinal parasites under control.
As always, we encourage you to read through all of the sources below and determine what is the best strategy for your specific circumstances.
Probiotic administration post-foaling may reduce parasite shedding in foals
R.D.Jacobs, M.L.Jerina, B.A.Tremayne
Journal of Equine Veterinary Science (2021)
Volume 100, May 2021, 103565
AAEP Parasite Control Guidelines
Armstrong, S.K., Woodgate, R.G., Gough, S., Heller, J., Sangster, N.C. Hughes, K.J., 2014. The efficacy of ivermectin, pyrantel and fenbendazole against Parascaris equorum infection in foals on farms in Australia. Vet. Parasitol. 205, 575-580.
Demeulenaere, D., Vercruysse, J., Dorny, P., Claerebout, E., 1997. Comparative studies of ivermectin and moxidectin in the control of naturally acquired cyathostome infections in horses. Vet. Rec.15, 383–386.
Rossano, M.G., Smith, A.R., Lyons, E.T., 2010. Shortened strongyle-type egg reappearance periods in naturally infected horses treated with moxidectin and failure of a larvicidal dose of fenbendazole to reduce fecal egg counts. Vet. Parasitol. 173, 349- 352.