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HorsesAreForever 11-21-2007 11:21 PM

worming????? help
when are u suppose to deworm ur horse i bought my horse a while ago and am boarding at a stable where i ride but i dont know when my horse was last wormed and when are u suppose to worm and what do u use??? Ive never dewormed a horse before this is my first horse ive owned but ive been around them and ridden, and leased since i was 2 and im now 15 ... so

thanks for ur replys :D

Vidaloco 11-22-2007 04:03 AM

Here is a worming schedule you can use.
Horse Worming Schedule
Month One A fenbendazole-based product such as Safe Guard.
Month Three An ivermectin-based product such as Zimecterin Gold.
Month Five A pyrantel pamoate-based product such as Strongid.
Month Seven An oxibendazole-based product such as Anthelcide EQ.
Month Nine A moxidectin-based product such as Quest.
Repeat Rotation
This is just a recommendation, I go every 3 months. It depends on your manure management and health of the horse IMO.
I also use a worming bit instead of just trying to stick the applicator in the horses mouth. Its a lot easier and less wasteful. I think they sell them at country supply ( you can check your local tack supplier too. Hope this helps. :)

EDIT: Make sure to write it down on a calandar the day you do it and what type. That way you can keep track of what and when.

Ryle 11-22-2007 01:34 PM

When to deworm and what with depends on several factors--
local environmental conditions
horse's age
how the horse is kept (stall, dry lot, pasture, boarding pasture, etc)
if pastured with other horses, are they on a regular deworming program

The environment where you are plays a big role in your deworming program because the weather plays a major role in how much of a parasite load there is on your pasture. In the summer months, the parasite load on pastures drops in the very hot deep south, in the desert parasite load is always pretty low, in the far north parasite load on pastures is very low (and horses aren't really getting much pasture time). Age is critical because very young and very old horses are more susceptible to intestinal parasites so they require more careful deworming. And you are looking at a different parasites as the main threat in very young horses than you are in adult horses and you have to be considerate of what dewormers are showing problems with those resistance in those parasites.
Management determines how much exposure horses get to infective parasite larva--stalled horses have much less exposure to parasites than horses that are pastured 24/7, etc. So, there is more than just going with the standard 6-8 week rotating dewormers.

Rotating dewormers is an old plan that was necessary back when the drugs we had available where not broad spectrum--one might get ascarids, another strongyles, etc--so rotation was done so that you were treating for all the different types of parasites. Then it was continued once we got better drugs available for deworming even though it's not necessary to be able to target the different parasites but in the hopes of preventing the parasites becoming resistant to the drugs. However, this has not been the case and with the situation we are now in there is very little "room" for rotating drugs (which in fact means rotating classes of drugs not just brands or chemicals) because the benzimendizole class (fenbendazole-Safeguard, Panacur, etc) is of very little use because of resistance issues in 95% of the world, and the pyrantel paste (Strongid, Equicide, Rotectin, Strongyle Care) has resistance issues in around 50% of the areas where it is used. The avermectins (moxidectin and ivermectin) are the only class of dewormer that doesn't currently have any resistance issues in strongyles which is the main issue in adult horses (though ivermectin resistant ascarids have been seen in certain areas and this is an issue for foals).
So, rotation options are limited at best and it's really not the rotation that is most important for preventing parasite resistance but appropriate dosing and treatment intervals.

You need to be SURE you are not under dosing your horses so always use a weight tape or measure your horse and calculate his weight. In studies even many vets were way off on weight estimations and they have the benefit of spending a few years working in situations where they get to walk horses onto scales daily to see what 900 lbs LOOKS LIKE.

Weight calculation information:
Body Weight Estimation of Horses KG calculation shown as well as a chart based upon heart girth measure (remember, the heart girth only assessment may be off by as much as 200 lbs just like weight tapes)
Horse Weight: Estimate It Easily How to calculate in pounds

As for appropriate dosing intervals, you want to treat according to the egg reappearance period so that you are dosing to prevent continual recontamination of your pastures. This method means that you will be cutting back on your horse's risk of parasite infestation significantly after a year appropriate dewormings because you will have cut the number of parasite larva on your pastures. It also means that you won't be deworming at a time when there are no parasites in the system that will be susceptible to the product you are using next which happens if you dose too soon after ivermectin or moxidectin with pyrantel or fenbendazole because at normal doses these two chemicals only kill adults in the GI tract and if you've dewormed with moxidectin last 8 weeks ago there aren't adults there to kill and you've missed the migrating larva which will then start shedding eggs 4 weeks after you treat with either of these drugs and shed for the 4 weeks until you deworm again. Or if you dewormed with ivermectin 6 weeks ago and treat with either pyrantel or fenbendazole you will start seeing egg shedding into your pasture in 2 weeks because you didn't have adults in the GI tract when you dewormed last but they will be there in a couple of weeks. Or in the case where you actually do have adults for the pyrantel or fenbendazole (which again is not likely to be working) to affect because it's been 8 weeks since your last dose of ivermectin you will again have parasite ova being shed in 4 weeks because that is how long after the use of either of those drugs you start seeing adult egg shedding parasites in the GI tract. So deworming based upon Egg Reappearance Periods, you would deworm and then deworm again based upon what drug you used last--4 weeks later for pyrantel (or Fenbendazole, though the next day would probably be more useful LOL), 8 weeks after ivermectin or 12 weeks after moxidectin. In this manner, you can significantly reduce the parasite load on your pastures in a year's time.

If you want to tell me a bit more about your horse, management conditions and weather where you are, I can help you figure out a decent deworming program. But it's really best to discuss this with your vet as well.

For a really good read on deworming, check out

Equina 11-23-2007 03:48 AM

The local environment and weather plays a big part in when you need to worm your horse (and for what strains). When I first bought my horse, I researched like crazy to develop "the perfect" worming schedule. I spoke with my vet for his opinion. I spoke with my barn owner and other boarders to find out what they do.

And, I think it was already mentioned, but be sure to give your horse the proper amount of wormer...or a little too much is okay. My horse is around 1100 lbs, and most wormers go to a max of 1200 lbs, so I just give him the whole tube.

Also, I read somewhere that a critical time for worming is after the first frost of winter (within 30 days). Many of the wormies and bugs living in the manure in your horse's pasture/muck pile will die from the cold, so it's a good time to pump him full of Ivermectin and kill anything that could be inside him.

I bought a Premium One-Year Wormer Pack from that included 6 wormers of varying types with a generic worming schedule for worming every 2 months. It was only like 35 bucks...the best deal I could find. I only worm every 3 months, so, buy supplementing this with a couple other tubes, I have my plan all set for 2 years. Oh yeah, remember to check expiration dates too!

Vidaloco 11-23-2007 06:00 AM

I was hoping you would jump in here Ryle. What thoughts on the daily dewormers?

Ryle 11-23-2007 11:35 AM

Daily dewormers can be very useful when you are in a situation where your horse is turned out on a pasture where many horses are kept and you have no control over the deworming of these other horses. In this sort of situation where horses of varying ages and with varying deworming programs have been on a pasture for years, the parasite burden in that pasture is likely to be quite high. And remember if you do go with a daily dewormer you need to deworm with ivermectin or moxidectin the day before starting the daily product and then with ivermectin/praziquantel or moxidectin praziquantel twice a year to treat for bots and tapeworms that the daily dewormers don't kill.

However, for the general horse owner with just a couple of horses on a pasture, it's going to be cheaper to go ahead and just deworm based upon season and egg reappearance periods or to pick up feces ever 2-3 days and deworm based upon the results of fecal egg counts. Both of these methods will minimize your pasture contamination.

Vidaloco 11-23-2007 12:36 PM

Thanks Ryle, I got really paranoid about parasites last year and started the daily deworming but it got too expensive. I keep a clean dry lot (daily clean out) in winter and they are on a large pasture in summer. I figured I was overthinking it.

HorsesAreForever 11-23-2007 12:56 PM

lol i think ill ask the person who owns the stable im boarding my horse is at lol i think im more confused about it lol >.< unless in you guys want to put in words that a blonde 15 yr old can understand lol!!

Ryle 11-24-2007 11:27 AM

Most often the boarding stable owners know as little about deworming as you do. :wink: If you can answer these questions I will try to help you figure out a good program for your horse.

1. Is your horse pastured with other horses?
2. How old is your horse?
3. If your horse is not pastured with other horses, what kind of paddock does he have? dry lot, grass?
4. What is your winter weather like and when does winter begin?
5. What is your summer weather like?

Equina 11-24-2007 10:00 PM

Hey Ryle, you seem very educated on deworming and the whole parasite life cycle. May I take you up on this offer to help devise a good worming program? I've only had my horse (first horse) for about 6 months, so I'm still learning too!

1. Is your horse pastured with other horses?
Yes. One other gelding in the same pasture. His owner does his own worming, but I'm not sure what he uses or when. About 20 other horses near by (separated by fencing). Stalled at night.

2. How old is your horse?
8 years.

3. If your horse is not pastured with other horses, what kind of paddock does he have? dry lot, grass?
Grass. Lots of mud by the gate & water trough areas.

4. What is your winter weather like and when does winter begin?
Rain. 40-50 degrees F in daytime. 30-40 nights. Winter (evening frost) begins mid-November...then gets a bit colder again in January.

5. What is your summer weather like?
Mild. 90 degrees would be a REALLY HOT day. 70-80 average in the middle of summer. Cool nights (50-65). Not much rain in the summer. Lots of rain in spring & fall.

We're in the Seattle area (rain, rain, rain) but a little more north and closer to the coast, so it's a little cooler.

Thanks for any advice you can give! I'm excited to compare your recommendations to the plan I made after taking to my vet and barn owner. I'm sure you're right that many barn owners aren't up to snuff in their deworming education!

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