Midwest Equine

Feature Article

Reframe the Parasite Control Discussion & Market Your Expertise

By Wendy Vaala, V.M.D., Dipl. ACVIM, Merck Animal Health

Article Archives LinkReframe Parasite Control - February 2018

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Traditional parasite control recommendations involving rotational use of anthelmintics at regular intervals were developed when Strongylus vulgaris (large blood strongyle) was the most important parasitic pathogen of adult horses. A lot has changed. Unfortunately, old habits die hard, and the traditional practice of widespread, frequent use of anthelmintics, often without the guidance and knowledge of a veterinarian, has contributed to the growing problem of drug resistance we face today in our equine populations.

Currently there are no new, resistance-breaking classes of dewormers on the horizon for use in horses, so it is crucial to encourage horse owners to work with you to customize parasite control programs. The challenge is to offer (and charge for) a comprehensive parasite control program that incorporates fecal egg count (FEC) testing into a farm-wide, herd-based program that combines chemical and non-chemical control strategies.

Goals of a Parasite Control Program

The AAEP Parasite Control Guidelines (revised 2016) suggest the following goals for a parasite control program:

1. Minimize the risk of parasitic disease in the individual

2. Control parasite egg shedding and environmental contamination

3. Maintain efficacious drugs and avoid further development of anthelmintic resistance as much as possible

There are several considerations when providing a comprehensive approach to parasite control, including understanding key parasite life-cycles, the mode of action and efficacy of the three major classes of equine anthelmintics (benzimidazoles, tetrahydropyrimidines, and macrocyclic lactones) and the advantages of various fecal egg counting methods available.

You and your client should discuss not only what parasites are problems on that particular farm, but also the role of fecal egg counts in selecting appropriate anthelmintics for their operation, and what non-chemical parasite control strategies are realistic. This approach is crucial to prolonging the efficacy of the three major drug classes we have.

The goal of a strategic parasite control program is not to eradicate all parasites from a particular individual, but to limit parasite infections so animals remain healthy with no evidence of clinical disease, and fecal egg shedding is controlled.

Marketing Your Knowledge

Although FECs are accepted as an important part of an evidence-based parasite control program, they are unlikely to become widely accepted if they are too expensive or offered only as random diagnostic tests. This is where you have the opportunity to market your extensive knowledge, in addition to diagnostics. This knowledge includes the distinct advantage of being familiar with the resident horse population and the local farm’s management practices. If you haven’t already, now is the time to schedule an on-farm visit to reframe the parasite control discussion with clients.

Fecal samples can help determine deworming needs, but because the majority of parasites may not actually be in the horse, but waiting to be consumed, it is important to visit the farm and evaluate ways to reduce parasite loads on pasture and break the transmission cycle. Consider providing a “physical exam” of individual farms using a simple questionnaire to capture information about management practices, herd demographics and deworming history. Evaluate the farm in terms of stocking density, size and overall condition of pastures and/ or paddocks, as well as labor available, to help decide which non-chemical parasite control strategies are realistic for that particular operation. All of these elements can impact parasite burdens and should be assessed prior to making deworming recommendations.

Top 10 Non-Chemical Parasite Control Tips

The following non-chemical control tips are part of a comprehensive parasite surveillance program, and can be shared with your clients. By making at least one annual parasite control trip to the farm, you can help the owner assess which ones might be realistic for his or her individual farm.

  • Don’t overstock pastures or allow pastures to become overgrazed
  • Remove manure from stalls daily and from paddocks and pastures twice weekly before strongyle eggs have a chance to hatch and develop into infective larvae (about 5 to 7 days during optimal conditions)
  • Keep pasture roughs (areas where horses defecate and do not graze) mowed to a height less than or equal to 3-8 inches
  • During hot, dry weather, harrow or rake pastures to disperse manure piles and expose larvae to sun. Rest the pasture a minimum of four weeks after harrowing
  • Cross-graze pastures with other species. Cattle and sheep serve as biological vacuums for equine parasites
  • Make at least one cutting of hay off some pastures to help reduce the parasite burden
  • Plant an annual crop such as winter wheat
  • Feed hay and grain in raised containers and not directly on the ground
  • Clean water sources regularly to prevent fecal contamination
  • Compost manure. Properly composted manure will kill strongyle larvae and many ascarid eggs

Now more than ever it is important for you to reframe the discussion on parasites with horse owners – not only to preserve the efficacy of the dewormers we have, but also to continually position yourself as a resource to owners in all facets of their horse’s care.

About the Author

Wendy Vaala, V.M.D., Dipl. ACVIM, joined Merck Animal Health in 2004. In her role as associate director life-cycle management, she is a driving force behind the company’s research and development efforts for the horse. She completed her internship and medicine residency at the University of Pennsylvania’s School of Veterinary Medicine, New Bolton Center, and was instrumental in developing the neonatal intensive care unit at that institution. During her time in private practice, Vaala served on staff at two large equine referral practices in New Jersey. Vaala has been a guest speaker at countless veterinary and horse owner meetings, authored many research papers and book chapters, as well as serving as section editor for several books.

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