Equine Parasite Control Part 2

Posted on August 1, 2018 by Jerrilee.
Categories: health, history, therapy.

Dr Donald Bliss of midamericaagresearch.net has published a revealing study regarding de-worming resistance in equines. His facts point out that actual cases of such resistance are very rare and that the appearance of  such resistance is usually the result of existing parasites and their eggs never fully being destroyed. To determine if your horse has resistance to current dewormers, Dr Bliss advises to first implement an active parasite control program that results in ending the egg-to-worm cycle in both the host (horse) and the paddocks and pastures.  The following is his initial program proven effective in stopping the parasite cycle in horses:

“Phase I:  To begin the program, all horses should be parasite-free throughout the winter months and prior to the start of the transmission season in the spring. This includes making sure all animals are free from harboring encysted larvae acquired during the previous grazing season. The goal has multiple benefits, the first is to make sure the animals are free from harmful parasitism during the winter months, the second, is to make sure the animals are not shedding worm eggs at the beginning of the grazing season in the spring and, the third, is to make sure all mares are parasite-free at the time of foaling. The last treatment of the season should take place after the transmission season is over, preferably in December. If post-treatment fecal exams indicate infections are still present after the December treatment, repeated treatment may be necessary including the use of the larvicidal dose of fenbendazole (10mg/kg daily for 5 days). All horses that are heavily parasitized (when fecal worm egg counts are over 300 eggs/3 gm sample) or horses that have not been dewormed on a regular basis should be dewormed with a larvicidal of fenbendazole to remove inhibited larval stages before starting the program.  When fenbendazole is given at 10 times the recommended dose spread over a five-day period it is successful against both developing and encysted larvae (10 mg/kg given daily for five days). By flooding the astrointestinal tract with molecules of fenbendazole, direct contact is made with the encysted larvae successfully killing them.

Phase II: Strategic Timed Spring Dewormings: In the horse, treatment should be timed with the seasonal parasite life cycle on pasture where parasite development in the environment in most parts of the country is the greatest in the spring and the fall.  To reduce the overall parasite contamination of the environment, three spring dewormings should be given one month apart in the spring and again in the fall.  If the animals are parasite-free at the beginning of the spring season, the first treatment should be given approximately 30-days after the start of spring grazing. The repeated treatment works because as animals pick up infective larvae which have over-wintered on the pasture in early spring, these larvae are killed with the first treatment before they can mature and begin laying eggs back in the environment of the horse. The horses continue to pick up more larvae, which are killed by the second and then the third treatment before they can shed eggs again.  By preventing eggs from being shed for the first three to four months in the beginning of the grazing season significantly reduces parasite contamination for the next three months. With horses, three strategically timed dewormings given one month apart will provide approximately six months of safe grazing. The key to the success of this program is that the horses must be free of parasites at the start of the season so that the repeated treatments are simply removing the parasites picked up during each thirty day interval. If the treatments are successful no worm egg will be shed on the pasture for approximately 120 days, i.e., (1) clean to start, (2) three thirty-day treatments which provides 90 days without shedding and (3) another thirty days past the last treatment before mature worms can be present laying eggs into the environment.
Strategic timed deworming treatment should be given three times in the spring and fall one month apart as shown. The class of dewormer used can be interchanged as desired. The last treatment should be given in late November or early December and may include both bot and tapeworm treatment if needed. Each “three-treatment strategically timed regime” provides approximately six months of control thus the spring treatment protects the horses until fall and the fall regime protects the horses until spring. These repeated treatments also help remove encysted larvae which may have survived in the horse through the winter months while preventing more from establishing throughout the entire grazing season by reducing the overall build-up of infective larvae in the environment of the treated animals.

Pasture Control:  Parasites can survive winter or hot summer conditions either as adult, inhibited larvae or infective larvae in the environment. The adult parasite within the horse have a finite life span, however, as the older parasites die off they are replenished by the larvae, new incoming larvae, or larvae that have emerged from the gut wall (in the case of the small strongyles), from the lungs (in the case of roundworms), and from the mesentery arteries (in the case of Strongylus vulgaris). Infected horses then re-seed the pastures with parasite eggs which develop into infective larvae contaminating spring pastures. Animals that enter the spring months harboring parasites begin shedding worm eggs immediately while those which begin the spring season parasite free will not re-contaminate their environment until a new infection has developed from newly acquired infection off spring pastures. As temperatures increase with spring developing, these eggs hatch and develop into infective larvae. The eggs that have been lying in the environment waiting for warm moist weather, many of these eggs will develop around the same time depending upon the weather causing high levels of contamination to occur once.  Pastures not grazed by horses from the beginning of the spring season for at least three months will become “parasite safe” pastures since the over-wintered larvae will have expired by this time and no new worm eggs have been released on the pastures. Any animals moving to “parasite safe” pastures should be dewormed prior to moving.
Treating horses strategically to prevent shedding eggs during the first three months of the season will accomplish the same goal and the existing larvae will disappear by late June or early July and the pastures will be safe from parasites until fall.”

no comments yet.

Leave a comment

Names and email addresses are required (email addresses aren't displayed), url's are optional.

Comments may contain the following xhtml tags:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>




equi-works

equi-works