Friday, April 16, 2010

The Scoop on Poop: Deworming

Deworming ("worming" or "drenching") is the process of dosing a horse with drugs to purge them of parasites. These drugs work by killing or paralyzing parasites so that they may be discharged from the horse's body....and that's the poop!

Horse owners have been battling equine parasites for centuries, beginning with old fashioned remedies that included blood-letting and feeding cigars to horses.

Tobacco was once thought to be a cure-all for man and beast. In 1565 a physician published a pamphlet about tobacco's medicinal powers. From the book Tobacco A Cultural History of How an Exotic Plant Seduced Civilization by Iain Gately, we read that tobacco was considered a treatment for many ailments:

Griefs of the breast...rottenness at the mouth, and for them that are short of effective cure for any illness of any internal organ, for bad breath, especially in children who have eaten too much meat, for kidney stones, from poison arrows, indeed for 'any other manner of wound'...Tobacco...could heal cattle of 'new wounds and rotten', of maggot infections, of foot-and-mouth disease, and of any parasite that had or might trouble them.

The mysterious plant from the New World was thought to be a wonder drug. We know better now. While some people still use tobacco as a backyard horse wormer, it is not recommended and can make a horse gravely ill.

Times have changed and veterinary medicine has advanced, thank goodness. But we must continue to wage war against the worms.

When I was young, tube-worming was the popular treatment for equine parasites. Twice a year the vet would come out and fill a big metal bucket with a chemical solution, insert a tube into my horse's nostril and pump the mixture into his gut. It looked very uncomfortable for the horse, and certainly not something I could do myself.

Then the practice of rotational paste worming took center stage and has been very popular and effective for several decades. Rotational worming allows the horse owner to easily dose their horse bi-monthly (every 2 months) by injecting a drug imbued paste into the horse's mouth, varying the chemical combination to target particular types of worms throughout the year.

Also popular is a daily pelleted wormer combined with occasional paste worming.

I have been a faithful follower of a bi-monthly paste worming rotation....until now.

My bi-monthly worming schedule has been so important to me that I keep the schedule posted on my dresser mirror, next to my earrings. (Not very decorative, but I know you horse lovers will understand).

I dutifully check the calendar to make sure I administer the appropriate paste wormer at the right time of year.

But now we are hearing more about those pesky, clever worms developing a resistance to our arsenal of dewormers. Last year my veterinarian suggested I change tactics. So in December, I used up the last of my paste wormer supply when I gave Misty & Marley their measure of pyrantel pamoate paste.

Last week I locked each horse in their own stall and waited for them to produce some manure. I didn't have to wait long. I strategically plucked several "apples" from different places in their piles, put them in separate plastic baggies marked with their names, and dropped these gems off at the vet clinic so they could do a fecal egg count.

The results...drum roll please...negative! Misty & Marley do not have worms to speak of. In fact, I was told "their manure looks great!" I'll take that as a compliment, thank you.

So what do I do now? Instead of paste worming 6 times a year, my vet has instructed me to paste worm just twice a year. And because Misty & Marley are worm free and it is just the two of them living at home, I don't need to submit another fecal sample for 18-24 months. Our new semi-annual schedule is:

Spring: Equimax (ivermectin/praziquantel), targeting roundworms, tapeworms, lungworms, and bots.

Fall: Quest Plus (moxidectin/praziquantel), targeting large strongyles, small strongyles, encysted cyathostomes, ascarids, pinworms, hairworms, large-mouth stomach worms, bots, and tapeworms.

I must admit...I'm a little uneasy about abandoning my trusty bi-monthly worming rotation. It's a paradigm shift of sorts. I'm taking a chance because I want to do what is best for my horses and thwart resistance in the parasite community. I trust my vet, but I will probably submit a fecal sample in 12 months for my own peace of mind.

Whatever strategy you choose to combat parasites, please consult with your equine veterinarian. Your vet can help formulate a plan based on the latest research, your geographic location, and your horse's living situation.

Interesting reading: Horsetalk's Parasite Series


  1. Cool! I trotted over here from Fearless Riding after I saw your post about this subject in her sidebar.
    I posted about the very same thing on my blog today, too!

    I'm glad I do the fecal tests on my horse, also, because I don't want to keep mindlessly cramming chemicals into my horse's body that she doesn't need, aspecially when worms can become resistant.

    Great minds think alike I see :)

    Good for you! (and your horses, too)


    word verification: wormedol
    lol! Sounds like a type of wormer...or a medicine to give a worm with premenstrual cramps. lol!

  2. In March, my vet was telling me to back off with the bi-monthly wormer due to resistance concerns. She didn't specifically say to get the fecal done, just to space out what I was doing. I much prefer your system!

  3. I remember all my guys being tube wormed years ago. It did look uncomfortable. Glad they have come out with the pastes instead. We use them now. We do try to rotate the wormers so the parasites won't build up a resistance to them.

  4. juliette, hmmm? Maybe ask for more detail. I don't think all the vets are promoting the fecal sampling yet. And maybe they vary based on location. I dunno. My last vet never mentioned it and kept me on the bi-monthly (I suspect because they are overloaded and wouldn't know what to do with all the crap if people started dropping off samples..ha, but that's why I switched vets; the service became terrible and unreliable because they were too busy...too many emergencies and they favored large ranches with a lot of stock over someone like me who just has 2 healthy horses). I just heard about it when I switched vets last year and the new one mentioned it to me right away. Then I started researching it while I used up my supply of paste and decided to give it a shot. But the new vet didn't give me all the detail until after the fecal sampling. First I was told to drop off a fecal sample at least 6 weeks after my last dose (I waited 12 weeks because I was still hesitant) and that we would go from there. It was after the results that the vet told me to paste twice a year.

    Laughing Orca...worms with PMS..that's hilarious! And what a coincidence. I'm heading over to your blog right now.

  5. Grey Horse, yeah, I remember my TB kind of gagging on the tube.

  6. That's very interesting information. I may rethink my own worming system.

    I really want your earring hanger, btw. Is that an antique?

  7. Hi Linda. Thanks for visiting. Nope, the earring hanger is not an antique. I've seen them in a couple of stores lately; they come with the gold dress and a black dress. I think I got this one at Bed, Bath, and Beyond.

  8. You asked if I have been doing the fecal tests on my horses for a while and this is only my first time with my new horse. My previous horse I was just told to worm twice a year because that is what is typical in our area. I wish I had thought to get her tested.
    It was interesting to see the reaction of my vet when I asked him to do a fecal on my current horse, Apache because he seemed very pleasantly surprised and said, that he wished more horse owners would do the fecal as she believes horses are being wormed more often than they need and with chemical wormers that are not needed. In fact he said that it's a fallacy that the rotational worming works in preventing resistance, because the same wormers are still being used. Eventually the worms will just evolve and alternate their cycles.
    Crazy, huh?

    Anyway, it's just really great to know what my horse has and not just mindlessly give her chemicals. I know I wouldn't do that with a human, or even my dog for that matter. Why then with a horse?

    I suppose it's cheaper because wormers can be bought in bulk now for cheap. And some people don't want to separate their horses so they can gather samples. I don't get it, but hopefully things will change, eh?


  9. this was a really cool post and i'm in the middle of transitioning from my old way (in america, every 8 weeks), to the european way (twice per year).

    i've had great difficulties obtaining wormers (cuz you have to buy them from a vet here).

    i'm slowly using up the supply of worm paste i brought from america last year. next year, who knows. i definitely worm less, but i still don't trust fecal egg counts cuz it would have to be done so often to be reliable, and the tests don't always show results for certain worm types.

    i'm totally on the fence here: )