Parasites and De-worming Programs

Internal parasites are silent killers. There are over 100 types of  parasites that can affect horses. They can cause extensive internal damage, and you may not even realize your horses are heavily infected.  At the very least, parasites can lower resistance, rob the horse of valuable nutrients, and cause gastrointestinal irritation and unthriftiness.  At their worst, they can lead to colic, intestinal ruptures, and death.

                Using de-worming agents on a regular schedule in combination with good management procedures is critical to relieving your horse of most parasites. Since parasites are primarily transferred through manure, good management is key.  In terms of management priorities, establishing a parasite control program is probably second only to supplying the horse with clean, plentiful water and high quality feed.

With the many safe, convenient products available today, establishing an effective de-worming program is easy.  A good parasite control program will go a long way toward maximizing your horse’s appearance, performance and comfort. 

There are a few strategies for ensuring decreased parasite loads in your horses. Whichever program fits your barn and horses, keeping the pastures free of manure and keeping horses less densely stocked in pastures will improve your likelihood of success.

Rotational De-worming

This program utilizes a regular rotation of different anthelmintic classes. Typically de-worming every 8 weeks and monitoring with fecal exams at least bi-annually. Fecal exams may not show larval infections and will not show encysted parasites therefore must be evaluated with the clinical signs of the horse. Additional de-worming for encysted parasites can be worked into this program.

Daily De-worming

Typically used in conjunction with the preventi-care program from Pfizer, but can be used as a de-worming program only. Also helpful for horses that will not tolerate paste de-worming. Utilizes a single anthelminthic class of de-wormer (pyrantel tartrate) fed daily to prevent maturation of larval stages of parasites and migration of large strongyles. Does not control tapeworms Twice annual targeted de-worming for tapeworms must be utilized with this program. Twice annual fecal exams are also recommended to rule out development of resistance to this drug class.

Fecal Exams and Targeted de-worming

With emerging anthelminthic resistance in farm animals and on some horse farms in the south, there has been a push to utilize targeted de-worming practices on farms. In this program fecal samples of all horses on a farm are evaluated for fecal egg counts on a regular schedule throughout the year. Only horses with rising fecal egg counts or routinely higher than average fecal egg counts are de-wormed with an appropriate anthelminthic. This program may work on small farms with excellent sanitation programs, a low stocking density, and minimal traffic. Unfortunately as noted above fecal egg counts can be misleading at times with horses having larval infections or encysted parasites. This program is not for all farms and specific populations should be evaluated with the veterinarians at Pine Meadow Equine.