Myth or Fact? I Don’t Need to Test or Deworm During the Winter

Press release

Some horse owners have claimed that they don’t test or deworm during the colder, winter months because it isn’t necessary. Over the last 10 years, Horsemen’s Laboratory has tested over 30,000 samples and found that 66.6% were negative (no eggs found on counting chamber) and 33.4% were positive. But are positive fecal egg counts affected by the time of year?

Three-Year Comparison Results
To determine if season of the year affects results, Horsemen’s Laboratory examined results for three years, comparing the month of January to the month of July. For additional insight, Horsemen’s Laboratory compared the percentage of low, medium, and high shedder for the months of January and July for the same three years.

The comparison showed that there was a difference of 2.6%–5.0% between the months of January and July for positive results over the three-year period. July positive test results were 3.7% to 4.2% higher than January positive test results over the three-year period. Three-year averages showed that:
• January positive results were 30% and negative results were 69.6%. Of the positive results, low shedders were 14.7%, medium shedders were 7.4%, high shedders were 7.9%
• July positive results were 34.4% and negative results were 65.4%. Of the positive results, low shedders were 16.6%, medium shedders were 8.2%, high shedders were 9.6%

Conclusion: It’s a Myth that Testing and Deworming Are Not Necessary
These slightly higher percentages substantiate the belief that there are more positive horses in the summer (July) than in winter (January). However, Horsemen’s Laboratory does not think that the difference is great enough to warrant not doing samples and deworming as necessary in winter.

About Horsemen’s Laboratory:

Horsemen’s Laboratory owner Dr. John Byrd has extensive experience with racing and breeding horses and oversees Westbrook Boarding Stable. He created Horsemen’s Laboratory in 1992 so that horse owners could better evaluate their horses’ worm control programs and make informed decisions about deworming their horses. Dr. Byrd was one of the earliest proponents of performing fecal egg counts prior to deworming. His recommendation has always been to deworm only when the fecal egg count indicated that deworming was necessary—long before anyone else in the horse industry was recommending the new deworming protocol of selective deworming. His early vision was to create a convenient method that would allow horse owners to have their horses checked for internal parasites rather than just routinely deworming them every 6-8 weeks or feeding daily deworming medication. Horsemen’s Laboratory has made it easy for horse owners to follow the new, recommended selective deworming protocol by providing easy-to-order kits, email test results, and periodic reminders for testing.