17/11/2023
🦄 Foal Parasite Management 🦄
Foals are born with no immunity to internal parasites.
The species that we worry about the most initially are roundworms /ascarids.
Strongyles can also be an issue, but are more likely to become a problem from cumulative exposure.
Immunity to some species happens over a period of several months(ascarids) some species take several years (strongyles).
Immunity to ascarids is lifelong and strong, so exposure as a foal, if managed correctly to reduce any organ damage, is not a huge concern.
It’s important to know if you have ascarid contamination on your property, as this will change the way you manage your foals. They are also a species that can cause organ damage if not treated appropriately. Contamination lasts for years as the eggs are environmentally stable and survive for long periods and stick to everything!
If you don’t know if they’re present of not, a faecal egg count at 12 weeks of age should confirm whether there are ascarids, as the worms start producing eggs at 10 to 12 weeks after infection of the foal.
The faecal egg count at this age is to not look at the actual counts but just to confirm the species present.
If ascarids are confirmed as present, drench the foal with a white drench (bomatak/panacur) at the time of the FEC at 10-12 weeks.
If you already know you have contamination by this species, drench with the white drench at 8-10 weeks, prior to the worms producing eggs.
If you don’t have ascarid contamination, the first drench can be later at 4 -5 months with an ivermectin based drench (promectin mini, equimax LV etc).
With known ascarid contamination, the second drench can be at 5 months old with a combination drench (feniverquantal, Equitak excel). If there is huge contamination of ascarids, as per the first drench, you could treat with the white drench first and follow up with an ivermectin to reduce the risk of obstruction.
The reasoning behind using the white drench for the initial drench is that it starves the parasites and they die over a longer period - several days.
Ivermectin based drenches are showing signs of not being so effective in treating ascarids in other parts of the world, but if they are effective, they kill the worms all off in one go, increasing the risk of obstruction by dead worms in the bowel.
Hence why the white drench is a better option as a first line treatment.
Foals then need to be drenched every 12 weeks from the drench at 5 or so months, as the immunity is not yet matured to combat the strongyle infections. This maturation occurs at about 3-4 years, but I have found it’s variable.
Immunity to ascarids, if they have been exposed as foals, should be very strong by weaning time but continuing the combo drench can be necessary on some individuals for longer, as occasionally, it can take a little longer.
Youngstock do not require moxidectin based drenches (Ultramox/Equest) until they are going into their second winter as a rising 2 year old.
Remember you don’t want your foals to be totally worm free either - exposure & the presence of worms at manageable levels, will ensure the immune system matures normally.
As a side note, treatment a month before foaling for the species strongyloides in mares, has become outdated. This species has proven to be non-pathogenic in foals.
Just ensure your mares are up to date with drenching according to their individual shedder status.
In larger horse only properties (eg stud farms) treatment of this species may still be mandatory.
⭐️Do not hesitate to get in touch to discuss this further and there is a pinned post at the top of the page explaining the process for FEC testing through Worm Watch.
⭐️I have limited amounts of Panacur to available to clients, as I stocked up prior to the product being discontinued.
