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Cydectin use in breeding ewes


NorthfieldNick
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  • 2 weeks later...

Fenbendazole is not labeled for sheep in the US. I do know that it's in the same family as albendazole, the active ingredient in Valbazen. I wouldn't use it for both of those reasons without specific instructions from my vet. In my experience a tapeworm infestation is not likely to do much damage in ewes for the few weeks in early pregnancy that Valbazen is counterindicated. In fact, I rarely see tapeworms in my ewes, and never in the fall.

 

Lambs are another matter ...

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Bill,

 

I was reading various posts on the sheep production forum regarding use of Cydectin in pregnant ewes and where ever I saw it mentioned, you said that you'd keep Cydectin "as the ace up my sleeve" a last resort wormer and instead go with another one such as levamasole. Granted these posts were pretty old, but I couldn't find anything newer.

 

Just to make sure I understand, Cydectin shouldn't be used in pregnant animals, correct?

 

Thanks,

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Bill is facing somewhat different worming conditions than we do down here. However, what he says about Cydectin is correct, but how you read it is not. Cydectin IS safe for ewes at all stages of the reproductive cycle, for lambs, etc.

 

I've stopped using Cydectin but not for worm resistance or issues of safety, but rather because I'm done with Fort Dodge. I use levamasole about three times during the season on the lambs, once at the beginning of summer and once at the end, and one more time in the fall for everyone (so six times in a year for lambs, three for adults). I do Valbazen once in summer for tapes, and I have a roundworm (the one that starts with o) that levamasole isn't that effective on, but Valbazen gets. I used to do Ivomec for flukes but our pastures here at the new place are dry.

 

I'm lucky enough to have enough space to provide clean pasture situations though I'm not currently using rotation as a formal method of worm control. Next year I will add that as a another level so I can maintain or I hope improve my pharmaceutical exposure. I leave out one individual of the treated groups each time so that non-resistant worms have a refuge. I started that last year and saw a big improvement in my late summer lamb loss.

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Hey Michelle,

Not Bill, but I can tell you what he's saying. Cydectin is safe for pregnant ewes, as still stated above. Because worms become resistant to wormers, if you have an alternative to cydectin that is working for you now, it's best not to use (switch to) cydectin, but instead keep using what's working. That way, when your sheep's worm population eventually becomes resistant to whatever it is you're using, you'll have something else effective to turn to: cydectin (the "ace up your sleeve"). For those of us already using cydectin, we have to hope that if the worm population becomes resistant that one of the older wormers will still work for us. The only wormer I know of that shouldn't be used during pregnancy is Valbazen, and as Bill notes, it would be wise to stay away from anything in that chemical class during early pregnancy.

 

J.

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Hey Michelle,

Not Bill, but I can tell you what he's saying. Cydectin is safe for pregnant ewes, as still stated above. Because worms become resistant to wormers, if you have an alternative to cydectin that is working for you now, it's best not to use (switch to) cydectin, but instead keep using what's working. That way, when your sheep's worm population eventually becomes resistant to whatever it is you're using, you'll have something else effective to turn to: cydectin (the "ace up your sleeve"). For those of us already using cydectin, we have to hope that if the worm population becomes resistant that one of the older wormers will still work for us. The only wormer I know of that shouldn't be used during pregnancy is Valbazen, and as Bill notes, it would be wise to stay away from anything in that chemical class during early pregnancy.

 

J.

 

 

The original post was for ewes that were just going in with a ram so they wouldn't be pregnant yet.

 

The Cydectin label states that it hasn't been tested on pregnant animals so except for one ewe that I knew Invermectin wasn't working on (and if she gets bottle jaw again after the dose of Cydectin, she'll be culled), I chose to use Ivermectin on those that needed worming instead of Cydectin.

 

My understanding about keeping worms from becoming resistent is to not worm all the sheep, just the ones that need it, so that's what I plan to continue to do. I still have sheep from my first crop of lambs over two years ago who have never been wormed so I guess things are okay for me. Then again, I have hair sheep who are a bit hardier than woolies.

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I'm lucky enough to have enough space to provide clean pasture situations though I'm not currently using rotation as a formal method of worm control. Next year I will add that as a another level so I can maintain or I hope improve my pharmaceutical exposure. I leave out one individual of the treated groups each time so that non-resistant worms have a refuge. I started that last year and saw a big improvement in my late summer lamb loss.

 

My sheep and goats are moved very frequently because I use ElectroNet. I went through my current crop of lambs and goat kids using FAMACHA and found at least six of them who did not need to be wormed so I didn't. Of course it's the last few that needed to be caught who didn't need to be wormed. :rolleyes: I did have two with bottle jaw who did not respond to Ivermectin and the goats came to me in pretty tough shape so they all were wormed earlier with Ivermectin.

 

On Saturday, we went through the adult ewes and we only had to worm four or five of them (out of about 25 animals). From my reading on the subject, 20% of the flock carry 80% of the worms. My partner and I will cull anything that ends up susceptible to worms or anything else. I'd rather not use chemicals if I can avoid it and I have plenty of space in my freezer and carnivorous mouths to feed the meat to.

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The original post was for ewes that were just going in with a ram so they wouldn't be pregnant yet.

True, but since most wormers have a withdrawal and most rams will get to work right away if the ewes are cycling, one could presume that if the cydectin is used right before putting the ram in that it would still be in the ewes' systems when they are bred. I've used cudectin for several years in pregnant ewes with no apparent ill effects. (FWIW, I also use the FAMACHA method and didn't really have to worm at all last year, most likely because of the drought, but after the recent rains, I have had to start worming more often, at least the lambs.)

 

J.

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True, but since most wormers have a withdrawal and most rams will get to work right away if the ewes are cycling, one could presume that if the cydectin is used right before putting the ram in that it would still be in the ewes' systems when they are bred. I've used cudectin for several years in pregnant ewes with no apparent ill effects. (FWIW, I also use the FAMACHA method and didn't really have to worm at all last year, most likely because of the drought, but after the recent rains, I have had to start worming more often, at least the lambs.)

 

J.

 

That's good to know given I did worm one pregnant ewe with cydectin.

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Without getting too far out on the parasitology limb, and with the disclaimer that my knowledge is that of an interested layman, here's my thinking behind Cydectin.

 

Here are the facts behind my thinking:

 

Cydectin is the only "new" wormer that we are likely to have for the next 10 years at a minimum.

 

Parasites that are resistant to ivermectin are susceptible to Cydectin, but the reverse is not true. In fact, it appears that exposure to Cydectin may actually hasten ivermectin resistance.

 

Ivermectin resistance is forever. It is a dominant genetic trait and is passed on even if you stop using ivermectin. Presumably Cydectin resistance will also be a dominant genetic trait, since it is in the same chemical class as ivermectin, and presumably resistance is via a similar mechanism. (This may not be true, but it's a lot safer to act as if it is.)

 

At the moment, I have not seen any evidence of resistance to ivermectin in the parasites in my operation. Knock on wood. Nor have I seen evidence of resistance to either of the other classes (levamasole and albendazole).

 

Given all the above, I don't need to use Cydectin. The longer I can postpone using it, the more valuable a tool it becomes to me. I would like to avoid using it until ivermectin starts to fail on me, which is why I describe it as the ace up my sleeve.

 

--------------------------

 

The concept behind selective treatment of sheep and goats for parasites that is described as "refugia" is that some parasites are not exposed to the chemical and therefore don't develop the genetic traits associated with resistance. In the case of ivermectin, there's probably very little point in this, because resistance is dominant and is going to increase in the population whether you treat all the sheep or not. And using bottle jaw as a guideline for treatment is like a firefighter deciding which cellar hole to pour water on.

 

By the time you're seeing bottle jaw, you have very sick animals that are susceptible to many diseases. Bottle jaw is a symptom of anemia so severe that the blood is separating and serum is passing through the tissues and collecting in low spots. Treating parasites might be a good first step, but you can't draw any inference about the efficacy of your parasite treatment based on whether the bottle jaw dissipates or not. Bottle jaw will dissipate when the animal holds its head up for a long enough period of time. The edema simply moves to another part of the body, where it will probably be doing more harm than it was under the jaw.

 

If I can convince shepherds of anything, I would hope that it would be that you should not try to use FAMACHA principles without getting the full training that goes with it. If you don't understand the theory behind FAMACHA, you can cause a great deal of needless suffering and death.

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