Yesterday we got all the ewes resorted into their secondary breeding groups and their fall/winter wormer done. We have to deworm with ivermectin drench after a hard freeze to kill the nose bots that infest sheep. Well we had a cold snap, then warm weather and there was a hatch of flies so we held off doing the dewormer. Then it got so cold that the thought of sticking a metal tube into delicate sheep mouths was horrible. Yesterday it warmed up enough that with a bucket of warm water to store the drench gun in we were able to get all the ewes done. Ewe lambs got done in the last weather hole. Still need to do rams and ram lambs but there aren’t as many of them. We’re now 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 sort of nasty pesticide as some folks think. Drenching is giving a carefully measured dose of a parasiticide via mouth. It’s been called drenching for hundreds of years. A lot of people seem to think it means the same in sheep management as it does when someone gets drenched and soaked to the skin but the terms are different. For nose bots the only effective drug is ivermectin. It’s a synthetic version of the same chemical found in some soil funguses. 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 was the old way of dealing with external parasites like sheep keds, ticks, lice and other nasty critters. It is called dipping. I’ve never heard of anyone still dipping sheep for at least the last 30 years and if it’s still done at all 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 for lice or keds we can pour a measured amount of an insecticide on them, much like you would use a mosquito repellant. The last time we did it we used a pyrethin based insecticide. We no longer have to rely on vats of nasty chemicals and the disposal problems that creates when you are done.
Our flock rarely gets infested with external parasites. So we only use an insecticide when we need too. But 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 are resting inside the sheep over winter. The fly can travel so it’s not perfect but it’s our only management option. We have until the weather warms up again to get the rest of the sheep done.