Something that continues to amaze me is the ingenuity fostered by the veterinary community. Take, for example, the approach to parasitism in ruminants. Small ruminants like sheep and goats are especially vulnerable to the effects of intestinal parasites, because the worm burden increases quickly on the close-grazed pastures on which these animals are raised. However, over time the parasite population becomes resistant to anthelminthic drugs and they stop working as well. What can vets do?
Well, they can monitor resistance to drugs to see which dewormer will be effective in a specific flock. One of the best ways is the Drenchrite test, an in vitro larval development assay where parasite eggs from pooled herd feces samples are hatched in the presence of different anthelmintics. The results that come back from the lab tell the veterinarian exactly which drugs this specific parasite population are susceptible and resistant to. A less expensive option is serial fecal floats, where the number of eggs are counted to determine whether a previous dose of dewormer was effective.
But I was most excited to learn about holistic approaches to parasite control. One example is using copper oxide particles in goats to reduce the number of Haemonchus contortus, the bloodsucking barberpole worm that causes significant disease and mortality in small ruminants. The copper particles work by damaging the worm’s cuticle, a type of exoskeleton similar to those of insects. Another option is to feed sheep and goats a plant called Sericea lespedeza which contains condensed tannins that reduce the number of barberpole worms and coccidia through an unknown mechanism. A Danish company has even produced a millet feed that contained spores of Duddingtonia flagrans, a species of nematode-trapping fungus that has been shown to neutralize nematodes living in the stomachs of small ruminants. It’s pretty exciting to learn about new ways to combat old problems, and I can’t wait to get the chance to try some of them myself.