Yesterday, we got all the ewes sorted into their secondary breeding groups. We also got their fall/winter worming done. We have to deworm with ivermectin drench after a hard freeze to kill the nose bots that infest the sheep. Well, we had a cold snap, then warm weather, and there was a hatch of flies, so we held off on the dewormer. Then, it got so cold that the thought of sticking a metal tube into a delicate sheep seemed awful. Yesterday, it finally warmed up enough that, with the help of a bucket of warm water for the drench gun, we were able to get all the ewes done.
The ewe lambs got done in the last weather hole. We still need to do rams and ram lambs, but there aren’t as many of them. We’re also set for the backup rams to go in on Monday.
For those who have no clue what drenching means, it’s not soaking the sheep in some nasty pesticide. Drenching means giving a carefully-measured dose of parasiticide via mouth. It’s been called drenching for hundreds of years. People seem to think that it means the same thing in sheep management as when someone gets soaked to the skin with liquid, but it couldn’t be more different. For nose bots, the only effective drug is ivermectin. It’s a synthetic version of the same chemical found in some soil fungi. Its drug effect is carefully controlled, unlike the natural version, but it’s very safe. Ivermectin is used in human medicine to kill internal parasites, too.
The sheep equivalent of getting “soaked to the skin” was the old way of dealing with external parasites. This method, called “dipping,” would kill sheep keds, ticks, lice, and other nasty critters. I’ve never heard of anyone still dipping sheep for at least the last 30 years, and if it’s still done, it’s very rare. Dipping was the only option to deal with external parasites until the development of safe pour-ons. Now, if we have to treat the sheep, we can pour a measured amount of an insecticide on them, much like humans use mosquito repellent. The last time we did this, we used a pyrethrin-based insecticide. We no longer have to rely on vats of nasty chemicals and the disposal problems they create.
Our flock rarely gets infested with external parasites. We only use insecticides when we need to. However, the nose bot comes every year, and it can cause sheep deaths. We try to reduce next year’s infestations by killing all the larvae when they overwinter inside the sheep. The fly can travel, so it’s not a perfect solution, but it’s our best (and only) management option. We have until the weather warms up again to get the rest of the sheep done.