Lamb Doctorin’: Flystrike

Disclaimer:  This is not a pleasant condition to talk about.  I’m sharing it to A)help other shepherds who find themselves dealing with it for the first time and B)to remain transparent to our customers.  Things like this are a part of raising animals and it’s our job to educate ourselves on how to best care for the animals and avoid the problem in the future.

The technical term for flystrike is Myiasis.  It is a condition where fly larvae infest an animal and feed on their living or dead tissue.  Blowflies are the most common parasite involved.  Apparently, flystrike is a big problem in the sheep industry.  However, most of the information I found referred to Australia and New Zealand as being most affected.  It appears to be far less common in the Midwest where we are.

Insecticides are available that can be applied as part of a routine flock health program.  Such products may help prevent the occurrence of  flystrike in susceptible flocks.  Most of the products I found were pour-ons.  Many of them that claim to specifically treat and/or prevent flystrike don’t have suppliers here in the U.S., only overseas.  I did find Permectrin II available through Valley Vet Supply.  Clicking on the label information reveals a recommended dilution rate for management of blowflies.  However, if you’re dealing with enough flystrike to warrant using chemical preventatives it’s time to stop and talk to your vet anyway.  He or she probably has a product that they recommend or other suggestions for you to try first.

There is a ton of information out there on good management techniques that may prevent flystrike WITHOUT the use of harsh insecticides.  Google “preventing flystrike in sheep” if you’re interested.  Basically, a clean dry environment is far better than wet, swampy conditions.  Blowflies are attracted to the smell of footrot so avoiding that condition will help avoid secondary outbreaks of flystrike.  Likewise, flystrike tends to appear on animals who have a wound or have a lot of manure built up on their rear ends.  Tagging the animals (trimming the wool around the backside) can help prevent the buildup of manure and thus keep flystrike away.  Routine tail docking is performed for the same reason – one less place for manure to hang around and attract flies.

In our case, tail docking is what brought on the flystrike.  We had one ram lamb born a little later than the rest of the lambs.  We didn’t get his tail and testicles banded early on like we normally would.  Instead, we did it about 2 weeks ago.  This isn’t the best practice for a lot of reasons so we’ve kept a close eye on him.  He had been eating and acting normal with no signs of a problem, and actually continued to eat and act normal throughout this whole ordeal.  Early in the week we noticed clumps of wool starting to fall from his tail.  Since his tail was larger than normal (due to him being older) it made sense that it would necrose more slowly so we weren’t overly concerned.  By Tuesday morning the tail was held on only by a bit of tissue but he had some bald patches on his rump.  Tuesday evening the tail had fallen off.  Brian caught him up so we could investigate the wool loss on his rump.  What we found turned my stomach!  There were maggots around and in his rectum, in his tail stub, and crawling in the remaining wool on his rump.  At that time his testicles were still hanging on but a couple days later when they came off that area also became infested.

Here’s how we successfully eliminated the maggots and led the lamb to a full recovery:

1. We physically removed all the maggots we could see.  Brian used water pressure from the hose to clear the area at least twice a day for several days in a row.  We originally tried gloves and picking/brushing them off but that was too time consuming and not nearly as efficient.
2. Pluck or shave to wool from the affected area and out several inches from where you see the last maggots.  This ensures the maggots aren’t spreading in to new territory.
3. Apply a wound salve and/or fly repellent ointment at least twice daily.  A thick layer over the entire area prevented the problem from recurring.  We used Tri-Care Wound Treatment initially to help with healing and then switched to Swat Clear when the skin looked better and our main concern was keeping the area free from flies.
4. At one check there were no maggots on the skin or in the wool but there was an obvious tract of maggots squirming UNDER the skin.  Brian lanced the area with a knife, sprayed the maggots out, and applied the ointment.  There was only a thin layer of dry skin to cut through and it did not bleed or seem to cause the lamb any pain when Brian cut it open.  It only happened once near the end of treatment.

We continued to check the lamb twice a day until there was no signs of maggots or irritation for several days in a row.  He’s doing great now although he does look a little funny with a bare butt!

My original treatment plan included temperature checks and penicillin injections but our thermometer wouldn’t work that first night and after that it became apparent that the lamb didn’t need antibiotics to recover.  He never went off his feed and we never saw any pus or other signs of infection.  If we had gone with antibiotics he would have had to go through the lamb sale for sure instead of being available for direct marketing to our customers.  We could have also used insecticides to manage the flystrike but since we don’t routinely have this problem we don’t have those chemicals on hand and would prefer to keep it that way.

Also, several things I read recommended removing the maggots in a way that they could be completely removed from the area and disposed of.  In our case this was not an ongoing problem and I didn’t feel that the other lambs were at much risk.  The maggots were washed down in to the deep straw pack in the lamb pen.  If we had other animals with bands still on their tails or open wounds it would have been a bigger concern and we probably would have moved the infected lamb to the cement aisle way and swept up the maggots after each check.

I’d love to hear about your flystrike experiences and what works for you!

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