Researchers from the Universities of Warmia and Mazury in Olsztyn, Poland, were interested in why horses in this region have small roundworms that are resistant to ivermectin. Scientists tested the absorption rate of ivermectin at different times of the year.
The first phase of the investigation took place in May. Nine warm-blooded individuals were administered a standard dose of ivermectin and blood was drawn periodically to determine medication levels. Faecal samples to test efficacy were also taken at regular intervals before and after deworming. it was done.
The same protocol was repeated on the same horse in November.
The research team found that the absorption of ivermectin varies by season. Drug concentrations in the blood of horses were significantly higher in spring than in autumn 4 hours after dosing. However, the effect was temporary. In both spring and fall, maximum ivermectin levels were detected within 36 hours after dosing.
Scientists suspect that this variation in absorption may be related to diet rather than time of year.In the winter, the study horses ate hay instead of grass. Hay is high in crude fiber that can absorb ivermectin until further breakdown in the horse’s digestive tract. They noted that the slow absorption did not affect the efficacy of the drug, and within 4 days, parasite eggs were completely eliminated in both groups.
Researchers have noted that diet can affect the absorption of other medications and drugs administered to horses.
See the EQUUS magazine for details.