Strategies for Treating Internal Parasites

Eliminating the chore of treating internal parasites in their flock is an antainable goal for many producers. For others it does not seem remotely possible or feels too risky to drop their treatment program.

If You Are Treating Internal Parasites:

Give consideration to when you will treat the flock for worms. Treating a few weeks before the ewes move out to spring pasture for lambing and again a few weeks before the ewes are due to come off of pasture late in the fall are common times. This allows the ewes to drop their worm load in an area they should not be returning to for six months to a year. Other treatment times will vary with the climate region and production cycle.

Avoid whole flock treatments if possible as treating animals who do not require it, will only serve to produce worms that are resistant to the drugs used. Treating only the animals that require treatment will also help decrease your cost of production.

The jury is still out on whether to stick with the same de-wormer for a period of time or to switch de-wormers every time you worm your flock.Many de-wormers are becoming ineffective due to a build up of resistance in the worms from overuse.

Treating internal parasites via giving an oral drench (liquid medication down the throat) is often preferred over injection as the oral drench goes straight to the stomach and no needle injection in the body is involved. However, if you are switching products you will end up using an injection variety at some point.

Either way give the chemical de-wormer on an empty stomach to increase effect.

Watch for indicators to help assess which animals to worm

• diarrhea or soiled rear end or dried dregs

• loose, taggy wool and lethargy

• low body condition score compared to average of the flock and without other good reason (such as triplet lambs at foot)

• bottle jaw, animals with high worm loads can develop a pouchy looking swelling along their bottom jaw line

• submitting stool samples for egg counts. This is recommended in almost every sheep book however it's not always a feasible or cost effective option. Not many large scale producers are actually inclined to do this.

• the FAMACHA test

Treatment is not the same as having a health program and providing mineral supplements. Treating an animal means giving it a remedy to combat a disease or sickness it already has.

Administering chemical de-wormers is a treatment for a specific problem not the solution. Treating internal parasites on a frequent basis is a sign that the mineral and feed program is not providing what is needed.

Realize that feed and minerals can be playing a bigger role than you think in helping your animals to cope with worms or any disease or detrimental health issue. Too much inappropriate feeds or lack of minerals will play a big role in how often you end up treating your animals for worms and other health issues.

Learning from Our History

Perhaps a hint to the solution for managing worms can be had in some of the literature from days gone by. Even though treaing internal parasites was not as prevalent a practice as it is now, more than one old text book mentions good feed, adequate and available minerals and pasture rotation as key elements to keeping on top of internal parasites.

"Lambs and weak sheep are especially afflicted by these pests, which frequently cause death, while strong healthy sheep, though infected, may show but little evidence of the fact."

"Good management seems to be the best remedy for these pests. Keeping the digestive organs in a healthy condition by the use of roots in the winter and vetches, rape or other succulent plants in summer, along with other foods, seems to be a preventive."

"In infested districts the pasture should be hurdled off and the sheep kept on one plot for about ten days and then moved to the next. This should be done from June to October. This method keeps the sheep from feeding over infested pastures, preventing reinfection, as at least two weeks are required for the eggs to hatch."
Quoted from Sheep Husbandry in Canada written by J.B Spencer, 1913

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