What Can Your Veterinarian Do for Parasite Control?

In-feed wormer? Pastes? Stomach tube? Field rotation?

With a myriad of choices, designing a worming program for your horse can prove quite cumbersome. Unfortunately, the increased availability of commercial parasite control has reduced the role for veterinarians in the planning and implementation of comprehensive programs.

Beware! Parasite control is complex and entails much more than deciding which of many available anthelmintics to select from the feed store or through the latest horse supply catalogue. Your equine practitioner is the one most qualified to address and oversee a program that best protects the health of your horse and your individual needs.

The following steps reveal how your veterinarian can work with you in managing parasites for your horse.

Step 1--Initial consultation and assessment

 You and your veterinarian should establish and evaluate the following:

  • financial capabilities of the owner
  • compliance capabilities of the barn
  • farm history
  • geographic location and climate
  • housing and management practices (number of horses, feeding regimens, etc.)
  • documented problems from the past

Step 2--Evaluation of the current parasite status

 To more specifically evaluate the current parasite situation, your veterinarian will likely collect, or ask you to collect, two or three fresh fecal balls from at least 20% of the horses on the farm. The horses chosen should represent the spectrum age and management practices employed on the farm. The results from the fecal exam will provide a very useful guide to overall status of the herd and degree of pasture contamination and transmission potential.

Step 3 - Evaluation and correction

 Did you know that you can eliminate most parasite species from the environment through a number of management strategies, without the use of dewormers? For example, the regular (at least twice weekly) removal of feces from paddocks and pastures, either manually or using tractor-powered vacuum units, has been shown to greatly reduce the number of infective eggs and larvae. Other strategies include:

  • regular mowing and harrowing of pastures (particularly during hot, dry weather and cold weather) can break up manure piles and expose eggs and larvae to the elements
  • frequent rotation of horses to fresh pastures
  • avoidance of overgrazing and overcrowding (more than one horse per two acres)
  • grazing horses with cattle and sheep
  • making sure that supplemental feed is fed off the ground
  • keeping visiting horses separate from resident horses and deworming before joining the herd
  • constructing feeders so that horses cannot pull feed onto the ground
  • cleaning both feeders and waterers regularly tominimize fecal contamination
  • deworming mares one month prior to foaling
  • thoroughly washing mares before foaling unless precluded by weather conditions
  • keeping mares and foals separate from other horses
  • reserving the cleanest, least-grazed pastures for foals and other young stock

Next month the Forum will discuss choices and the appropriate strategies for administration of anthelmintics.

About the Author

W. David Wilson, MRCVS

W. David Wilson, MRCVS, of the University of California, Davis, is chairman of the Biologic and Therapeutic Agents Committee of AAEP, and Edward W. Kanara, DVM, of the University of Pennsylvania, is the AAEP board liaison to that committee.

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