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Adult Horses

There are three forms of deworming your horse.

  1. Paste dewormer given on a rotating schedule throughout the year.
  2. Daily dewormer given in feed daily.
  3. Deworming by your veterinarian via gastroesophageal tube.

I personally practice #1 above with a little difference, and a typical year for an adult horse would go like this:

January: pyrantel pamoate
March: ivermectin plus praziquantel
May: fenbendazole
July: ivermectin plus praziquantel
September: pyrantel pamoate
November: ivermectin plus praziquantel
January: fenbendazole

The typical rotating schedule would just rotate the three types, but I like to use ivermectin praziquantel more frequently as it is very broad-spectrum and has not shown to develop resistance.

There is some literature that states you should deworm your horse on a fasting stomach as it binds to the food (protein) and passes through the system. I don’t know whether this holds a lot of truth or not, but it makes some sense, so I usually deworm in the morning before feeding. I also will usually give a small dose of electrolytes in their feed that evening.

Another important factor to consider when deworming is your competition schedule. I would not deworm a horse within ten days of competition or within two days after competition. It is safer to deworm after competition than it is prior with the best parameter being two weeks prior to competition. Deworming places extra stress on the horse’s body and could affect his/her performance.

Some horse owners find it easiest to feed a daily dewormer. I personally don’t like the idea because I believe the pesty parasites could develop a resistance to the deworming agent, but I don’t have any concrete information to persuade someone away from using this method. I would, however, deworm with a paste ivermectin plus praziquantel two to three times a year.

Deworming via gastroesophageal tube (often called “tube” deworming) is done by a veterinarian and is not as commonly done as it used to be. I am sure some horse owners still use this method, which is once or twice a year, but I have been told that as long as you use a good deworming schedule, such as the rotating schedule, and it is done on a concise routine basis, you should not have to do the “tube” deworming.