Pyrantel (Strongid, Rotectin 2, etc)

Strongid and Pyrantel Use in Horses

by Robert N. Oglesby DVM

Introduction

Introduction » Use » Pharmacology » Pharmacokinetics » Adverse Effects/Warnings » Overdosage/Acute Toxicity » Symptoms of Toxicity » Drug Interactions » Doses » Availability » Storage » More Info & Discussions

The dewormers (anthelmintic) pyrantel pamoate and pyrantel tartrate have been made popular to horse owners under the name Strongid. Available as a suspension, paste, or granules, strongid is an anthelmintic that while not that useful as a paste given periodically does have some unique properties that make it a valuable dewormer. This includes daily administration as a preventive and increased dosages for controlling tape worms. This article discusses the properties of this drug, including toxicity and effectiveness, recent news about resistance, and gives recommended usage.

Use

Introduction » Use » Pharmacology » Pharmacokinetics » Adverse Effects/Warnings » Overdosage/Acute Toxicity » Symptoms of Toxicity » Drug Interactions » Doses » Availability » Storage » More Info & Discussions

Note it is becoming increasingly apparent that resistance to this product is growing. This product should not be used without rotation with other products. It is unknown if used in rotation that resistance will continue to be a problem at this time. Monitoring of efficacy is imperative. In long-term studies of daily pyrantel granule use and in surveys of farms using the product, it is very effective for up to several years, then resistant small strongyles, large strongyles, and round worms appear and the efficacy drops from more than 90% to 60% when egg counts are used to measure efficacy.

Pyrantel can be bought in suspension, paste, or pelleted form. The paste should not be the mainstay of any deworming program as efficacy is not as high as the avermectins and egg production of the strongyles is suppressed for just a short time. It is effective at a double or triple dose for tape worms. Given orally as a one time paste it is effective against the following parasites in horses. Note the variable activity against small strongyles, pinworms, and one specie of large strongyle:
  • Strongylus vulgaris and equinus
  • Parasacaris equorum
  • Probstymayria vivapara.
  • tapeworm (A. perfoliata) when used at twice the recommended dose.
  • variable against Oxyuris equi
  • variable against S. edentatus
  • variable against small strongyles.
The daily granules are thought to be more effective and this variability may be due to developing resistance.

Strongid and "Rotectin 2" pastes

Most horses on paste dewormers during the year need a-once-a-year deworming for tape worms whether they show up in the fecal or not. The deworming is given right in between the regular deworming pastes and not substituted for them. At this time cold weather seems to be the best time to deworm, but this is uncertain and any time of the year will do. If tapeworms are established as a problem twice yearly dosing with a 3X dose of pyrantel and switching over to pyrantel pellets (see below) may be warranted.

Strongid Pellets

The administration of the daily pellets is more effective than the pyrantel-based pastes for regular deworming and control of strongyles and round worms. Pyrantel tartrate pellets (Strongid and now there are generics), is a feed-additive dewormer that kills larvae as they are ingested. The larvae never have a chance to take hold. When beginning the pellets, you must give a good deworming with ivermectin or moxidectin to eliminate the already existing adult parasites that reduce the encysted parasite larva. You will also need to deworm twice a year for bots with ivermectin and Quest as this product is not effective against them.

Fecals should be run just prior to the bot treatments as breakthroughs will occur if any treatments are missed. There is reduced efficacy of this product in immature horses so frequent fecals and more frequent use of good pastes are suggested.

Research is showing that the daily use of pyrantel tartrate pellets is very effective at controlling the common tape worm infections of horses. It effectively suppresses egg production so that in several years the infective larvae die off the pastures. It is still uncertain if it kills the adults though we suspect it. If tapes are a known problem, you should give a 2X or 3X treatment with pyrantel paste. Otherwise no other treatment is required for them than the pellets.

Pyrantel Pellets Expensive, But for Some Worth It

This is an excellent product but expensive. The cost of the product runs approximately $15 a month per 1000 lbs. and one or two ivermectin dewormings are still needed each year to control bots. For people who have horses on pastures where they do not control all the horses' deworming programs this product is worth every penny. This is the only product that will protect your horse from a contaminated pasture. The result will be fewer colics, a better hair coat, and less feed required.

Many owners report significant improvements in weight and appearance after beginning Strongid pellets. This occurs even in some horses with good deworming programs. However, this product is not worth the cost if the following conditions apply: (1) all the horses that graze with yours are regularly dewormed either every 42 days with ivermectin or every 84 days with moxidectin (Quest). and (2) your horse needs less than two lbs. of feed a day to keep him fat!

Pharmacology

Introduction » Use » Pharmacology » Pharmacokinetics » Adverse Effects/Warnings » Overdosage/Acute Toxicity » Symptoms of Toxicity » Drug Interactions » Doses » Availability » Storage » More Info & Discussions

                       
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