Do You Practice Risky Business?
Are you living on the edge when it comes to parasite control? Are your risky behaviors setting you up for resistance problems down the road? Dr. Mark Alley, DVM, senior technical service veterinarian, Zoetis, offers a list of common practices that could result in resistance issues, ineffective use of products or unneccesary costs.
Estimated or Average Weights
Often we don’t weigh animals and we dose for what the average is. Many producers don’t have a set of scales, or if they do, they don’t use them or check them regularly to make sure they are accurate. Dosing to the average means a percentage will be underdosed, which can lead to resistance in a worm population. Overdosed animals are costing more to treat than is necessary.
We deworm when it’s conventient for people, not necessarily when it’s the best time to kill parasites. As a result, parasites might not be active on the pasture. We need to think through that process. It’s best to have some level of succesbile parasites on the pasture so when the animal grazes, they are picking up susceptible parasites that will be killed by the dewormer. Deworming after spring green up and again in the fall will get the most out of your deworming program.
Reduced Dose for Fly Control
Topical dewormers are so conveneient and easy, some producuers use them for fly control at a reduced dose. It doesn’t take much of a topical product to reduce flies, but as a result, internal parasites are exposed to the product at a reduced rate that can lead to resistance.
Deworm All Animals at the Same Time
Instead of treating all animals, treat those most susceptible to internal parasites, especially calves and younger animals. Parasitologists agree that no dewormer provides 100% effectiveness against parasites. The idea of refugia (leaving some non-resistant parasites to dilute the resistant population) helps reduce resistance.
Dr. Alley says producers can’t tell visually if there is a resistant parasite problem in the herd. Producers make the assumption that all parasite control products are 100% effective, but even with 50% kill of parasites, producers will see a clinical improvement in the animals. They need to work closely with their veterinarian to diagnose presence or absence of resistant parasites and establish a strategic deworming program that will simultaneously minimize production losses and maintain efficacy of our parasiticide products.