Keeping goats is not as easy as it once was. Internal parasites, specifically the Barberpole worm or Haemonchus contortus, are the number one killer of goats around the world. There was a time when we had an arsenal of dewormers to choose from, but today we face parasites that are developing resistance to dewormers faster than we can invent dewormers to treat them. In many regions of the country these worms are now resistant to fenbendazole (SafeGuard) and other drugs in its class. They are largely resistant to ivermectin and related drugs.
Here at Rosasharn Farm we use the FAMACHA method of parasite management by checking for anemia, the primary sign of a high barberpole worm load, and then treating only the individuals who are determined to need treatment.
The less we expose the worms to the drugs, the longer we will be able to use those drugs to treat the worms. We primarily rely on levamisole (Prohibit) to treat barberpole, and reserve ivermectin as a last resort. In our region we can still rely on fenbendazole for control of tapeworms. Pasture rotation and use of dry-lots are important tools in helping to limit exposure and re-infection.
These days too, we are seeing more goats with signs of skin issues associated with sensitivity to external parasites. Sometimes we notice lice or signs of skin mites; excessive dandruff, flaking skin, dry, rough cracking areas and hair loss, especially around the ears, muzzle and lower legs. Certain individuals in a herd will show hypersensitivity, or an allergic reaction to external parasites. They might be viewed as the “canaries in the coal mine” of our farms. There are several factors that likely contribute to signs of skin issues: a mineral imbalance is a very likely precursor to the development of hypersensitivity to external parasites. This becomes more complex since high iron content in the water (as we have here) inhibits the absorption of copper, zinc and other trace minerals.
Upon researching and discussing the issue of external parasites with my vet and several goat parasitologists, we hypothesize that in the days when we used to use the ivermectin-related dewormers regularly, including Moxidectin, Cydectin, Ivomec, Eprinex, etc, we inadvertently controlled for external parasites.
Since I, and goat breeders in general, have cut way back on the use of these dewormers, saving them for barberpole only as needed, we are seeing a number of goats showing more sensitivity to external parasites such as mites and lice, especially when they are stressed and when they are not getting the mineral balance they need.
Our protocol for maintaining our goats includes strict attention to their nutrition, supplementing/topdressing their grain with black oil sunflower seeds and rice bran, rigorously keeping up with high quality loose minerals (Sweetlix is our favorite), and using extra supplements as needed such as the injectable Multimin, chelated mineral supplements (EZ Pels by Blue-seal, and Replemin paste), Zinpro, and copper bolusing. An essential part of our regimen is lime sulfur “sponge baths” with the goal of treating the parasites externally so as not to exhaust the limited efficacy we still have from ivermectin. These are easiest done in warmer months or southern climates when the goats can be clipped often, which also exposes them to UV light. We apply over-the-counter moisturizing lotions and body oils as needed to provide relief from the dryness and itching while they heal.
The topical applications of pyrethrin products may also helpful in managing external parasites. On occasion, we do administer injectable ivermectin to a particularly severe case and our vet has given a steroid injection to get a few of the goats “over the hump” of an apparent allergic reaction related to external parasites.
As with internal parasite sensitivity, there may very well be a genetic component to the hypersensitivity to external parasites. Just as we make breeding decisions in order to complement other strengths or compensate for other weaknesses, we should try to select mates for hypersensitive individuals that have a particular strength in this area and strive to find an out-cross mate to achieve some hybrid vigor, thus avoiding breeding animals with this sensitivity to their relations.