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 wind...an 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