What kind of wormer do you need? These days research
is pouring in that the usual way of just using Ivermectin or what's on sale every 8 weeks isn't very effective. There are
many articles available on the "how's" and" why's" of that very subject, so I won't delve into them too
However, it would pay to be
a little careful in choosing what chemicals you are using. Rotation of the chemical class prevents worms from becoming resistant
to the drugs and each drug targets different species, so rotation is a good idea to cover all your bases.
Just a little caveat. Arbitrarily deworming every
month or two may do more harm than good. The chemicals themselves are irritating to the horse's digestive tract and kill helpful
bacteria in his gut. Horses that already have health issues may actually do WORSE when de-wormed excessively. Also, deworming
is not meant to compensate for not keeping pens and stalls clean!
Older horses and sick horses that seem to carry more worms than pasture-mates are showing
signs of poor immune systems and can indicate more than a mere parasite issue and the use of chemicals to kill worms may not
be a priority in all situations. Parasites do serve a role in nature, after all, of helping to weed out the weaker of the
species, so overburdened animals should be examined for underlying medical issues. Young horses' immune systems are stimulated
by exposure to some worms, so a mild parasite load may not be as harmful as previously thought. Many healthy adult horses
immune systems keep the worm load under control.
- Ivermectin is a broad spectrum wormer chemical that most
people know as "Zimectrin". It does kill more species than most other chemicals available, but worms are becoming
resistant, and it still can't kill everything in every (life) stage. It's useful for bot-fly larvae that cause gastric ulcers
as they imbed in the tissues. Many other wormers can't kill those. Usually best to use this in late spring and fall
after the bot fly itself has quit laying those yellow eggs on the horse. It's best to physically remove the eggs from the
horse before he licks them off. I use a bot knife or old razor to scrape them off.
- Fenbendazole, Oxibendazole, (the -bendazole family of drugs) known as Safe-Guard, Anthelcide
EQ, Panacure, are recommended more in early spring and late winter to help with small and large strongles, pinworms,
roundworms (ascarids) and has a safe margin of error on over-dosing. Theses are worms that are kept in check with sanitary
conditions and good, overall healthy immune systems. However, overpopulation of horses in pastures or dry-lots increases the
amount of worm eggs the horse is exposed to, so keep your pens cleaned as much as possible.
- Pyrantel Pamoate,
known commonly as Strongid that is most effective in mid-summer. Pyrantel Tartrate is often used in daily dewormers, which
I do NOT recommend. Continuous deworming may lead to more worm resistance and research is showing that a light parasite load
is not actually harmful for the horse, so being excessively "clean" may actually be harder on the horse by weakening
his immune system from lack of stimulation. Just like exposure to some germs is healthy and natural, so are a few worms.
which is also commonly used in dogs and cats. It kills roundworms, and I'm not sure if much more than that. Usually sold as
a liquid you pour on the feed.
- Moxidectin, or "Quest" kills pretty much everything. Hairworms,
threadworms, lungworms, ascarids, BOTS, large and small strongles, pine worms, stomach worms just as ivermectin does. Not
as safe, so don't use in pregnant mares or colts/fillies under the age of 1, or very sick horses or those with huge parasite
loads. It is so effective the mass dying of parasites throws off too many toxins for weak animals to cope with. Ivermectin
is safer in pregnant and young animals.
- Praziquantel is for tape worms. It's usually added in with Ivermectin or Moxidectin
as tape worm control. I would have my horse tested before bothering to deworm for them. After-all, why waste the deworming
power if it's not needed and save your horse the potential tummy ache if it's not needed.
What does my
wormer program look like?
I pick my "dry lot" as often as I can, no less than twice a week. They are on pasture at night, and I don't bother
picking that. I do feed on the ground, but not in "toilet areas". I only de-worm every 3 months at most, less often
in the winter when worms are less active. I rotate my drugs, depending on season, and what is needed. If I get new horses
in, if they have a heavy parasite load, I start them with pyrantel pamoate or fenbendazole initially, regardless of season,
then follow up a couple of weeks later with ivermectin or moxidectin. Then they fall in line with the rest of my herd
on rotation if that was sufficient. I don't use the same chemical twice in one year, just because there are so many options.
This year I started with Moxidectin and next will be Pyrantel Pamoate, in the fall it will be Ivermectin. Next spring will
Remember that deworming is hard on the digestive tract. I don't like to over-use drugs, regardless if pain killers or antibiotics
and dewormers should be treated the same way. Over using dewormer, overdosing in extremes could trigger laminitis. It would
be a good idea to give them some pro-biotics afterwards to repopulate the gut flora to avoid too much tummy upset. Most horses
will eat plain yogurt for this, or you can buy commercial supplements. I like to buy horse cookies with the probiotics in
them and they are a treat.
If you need a fecal test done, you can ask your vet. Some catalogs now sell mail-order test kits. You ship a sample of fresh
poo to a company and they tell you what your horse has and if he needs dewormed. Well worth $20 if you are in doubt!