Help with Worms
The time when one administers a de-wormer during the year is significant, says Craig R. Reinemeyer, DVM, a researcher and instructor at the University of Tennessee. Research, he says, indicates that de-worming programs work best if treatments are concentrated during the times when climatic conditions are favorable for the hatching of eggs and development of larvae.
Many horse owners who live in cold climates, says Reinemeyer, mistakenly believe that cold weather breaks a parasite's life cycle. Cold has little effect on survival of parasite eggs, he says. By contrast, heat can be a destructive force.
The parasite eggs, he says, are similar to plant seeds in that they flourish at temperatures that range between 45° and 85° Fahrenheit. When temperatures get higher than 85°, he says, the eggs often are destroyed. What this means, in Reinemeyer's opinion, is that the emphasis on controlling parasites in many areas should begin in early autumn and continue through February or March.
Basically, he contends, there is no need to deworm during the hot summer months because little transmission occurs at that time. The horses themselves tend to assist in keeping themselves parasite-free when on summer pasture. They will, whenever possible, graze on the "greens" of a pasture rather than on the "roughs," where they have left piles of manure--avoiding the ground around their fecal deposits.
However, as the summer season wanes and the greens disappear, the horses will graze closer and closer to the roughs and in the process will end up consuming grass that might be harboring large quantities of parasite eggs. The magnitude of the parasite problem is underscored by the fact that there are more than 150 types of internal parasites known to infect horses.
Environmental Control will Aid Parasite Control
1. Remove feces routinely to decrease transmission of eggs and larvae; do not dispose of feces on pastures or near water or feed supply.
2. You may harrow pastures to break up fecal pats and kill larvae only in hot, dry weather or below-freezing weather.
3. Quarantine all new additions to your herd and perform fecal examinations on them.
4. De-worm all horses at the same time.
5. Evaluate parasite control via fecal examination of 10 percent of horses two or three times per year, 14 days after de-worming.
6. Consider a daily wormer if you have small paddocks--less than 2 acres per horse.
"If environmental control is adequate, less than 10 % of samples obtained should contain eggs," says Dr Higgins. The best way to develop an effective parasite control program is to contact your local equine veterinarian, who will know the prevalent parasites and transmission in your area.
