Why Do Sheep Get Maggots?

sheep in a gathering pen, image from The Sheep Game (YouTube)

Maggots, yuck! What on earth are those things doing on sheep? And why are some sheep getting maggots to begin with?

Flystrike (maggots) in sheep is generally the result of manure around the tail of the sheep. The manure soiled wool attracts the female blowfly, which lays her eggs on the sheep. Those eggs quickly hatch into maggots that eat the manure and then the flesh of the sheep.

Sadly, any animal can get maggots: cats, rabbits, chickens, and, of course, sheep.

Do All Sheep Naturally Have Long Tails? will have a small section on docking tails, which is a common way farmers and ranchers try to avoid maggots on sheep.

Sheep get maggots in wounds and wool that is soiled with manure

Sheep can get maggots in wounds, sore or unusually irritated areas, as is the case with sore feet, or anytime the wool is wet with manure, which can happen around the tail in the spring, due to the lush grass or internal parasites.

Maggots tend to be a seasonal problem, most commonly in the mid to late summer, but not in the winter or spring because of the colder weather.

Maggots also tend to be more prevalent in the summer, since any grazing livestock are more likely to have parasite problems in the summer. Parasites stress the sheep and tend to cause changes in the manure.

One of the ways a sheep reacts to internal parasites is produce more runny poop, which then sticks to the tail or wool on the breech (the back of the rear legs). This soiled wool invites in the flies.

Sheep with maggots have flystrike

When a sheep has maggots the sheep is said to have flystrike. Flystrike can happen to sheep of any age, but tends to affect weaker sheep first.

Disadvantages Of Raising Sheep is an article I wrote to go over the not so great aspects of raising sheep, with their poor recovery to stress being a big one that applies to flystrike.

This is Cammy Wilson, a shepherd and shearer in Scotland, showing how he prevents flystrike on his sheep. Check out his channel, he’s fun and always has an interesting video.

Flystrike is caused by blowflies

The fly that causes flystrike is the blowfly. The blowfly is a very round shaped, iridescent fly that hovers around sheep with wet or soiled wool.

In my experience, these flies mean business. If you see these characters hovering around one of your sheep, catch the sheep now. Seriously. If blowflies are interested in that sheep, you need to immediately catch her and see why.

Flystrike can happen to adult sheep and/or lambs

Both adult sheep and lambs can get flystrike. We have seen flystrike on backsides, tails, sides, ribs, heads and feet.

Ewes tend to get flystrike on the tail area or feet. If the ewe has maggots on her side, like in the armpit area, in our experience those maggots are from her feet that traveled up the wool when she was sitting down.

Lambs tend to have flystrike in their feet, between the toes. When you see a lamb hobbling, or walking with it’s weight shifted to the back, you need to check the feet for flystrike.

Flystruck sheep will be sore and slow

Any sheep with flystrike will be slow and sore. This is understandable for the sheep and helpful to you since you can see the flystruck sheep moving slowly or lagging behind the rest. Catch the sheep and see what’s what.

Actually, not feeling well or just being sore seems to make the sheep worse. They sit around, so they are not eating and are not willing to go get water unless they are really thirsty. I feel this only adds to their stress.

Flystrike can be treated with spray on insecticide

Whenever we find flystrike, we use a spray on insecticide called Catron. It’s the best spray we have found, so far.

There are preventative pour on products available in other countries to keep flystrike from happening, CliK is the one I can think of that is available in the U.K and Australia.

There are no preventative flystrike medications for sheep that are available now in the U.S., as far as I am aware. If you want to find something for your sheep, ask your vet for advice.

Estimates Of Genetic Parameters For Breech Strike and Potentail Indirect Indicators In Sheep shows the relationship between dags (balls of poop on the backside) and the likelihood of a sheep getting flystrike.

Untreated flystrike can kill sheep

The big deal with flystrike, aside from the pain to the sheep and the disgusting aspects, of course, is that flystrike left untreated can and does kill sheep.

You have to get flystrike under control early, the larger the area that is struck, the more stress is it causing the sheep and the harder it will be to fix.

Here’s how we deal with flystrike:

Catch the sheep and spray with Catron. We spray more than the infested area, to make sure we get all of the maggots, since they can crawl to other parts of the sheep. Look around, make sure all areas that need spray have it.

If infested area is small, this will do it. We mark the sheep with spray so it’s easy to see her and keep track of if she is getting better or needs caught again.

If the flystrike is in the feet, we trim the hoof, if needed, before spraying. We then mark the sheep with a spray on mark, like Marksman spray.

If the sheep is really stressed, we take the sheep to the barn and monitor her individually. She’ll be shorn, at least around the infested areas and treated with the Catron.

It’s never good to separate a sheep from the flock, but if she’s too overwhelmed to get food and water for herself, then she needs to be inside where we can watch her more closely. When she recovers, she can go back out with the flock.

Cull any sheep that get flystrike

Flystrike susceptibility seems to be genetic. When a few individuals out of the group get struck, you need to cull them. Don’t keep around weak genetics and certainly don’t keep replacements, ewes or rams, from any of these sheep!

If a large portion of your flock has flystrike something else is up, this is now looking like a significant management problem.

Blowfly Strike is a NADIS from the U.K. on flystrike if you want to learn more or see some pictures. Warning, some of the pictures are graphic.

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