Using Dewormers Correctly

Episode 24
For the Love of Goats

Using Dewormers Correctly featured image

There is probably no other goat-related subject that confuses goat owners more than deworming. If you check five different online sources, you could wind up with five different recommendations about how to use dewormers. The problem is that there was not much research done on worms until the last 15 years or so, which means there are a lot of outdated recommendations still floating around online. And it’s also challenging to get the new info to veterinarians, so some of them are even working with outdated information.

In this episode, I’m talking to Susan Schoenian, a sheep and goat specialist with the University of Maryland’s Western Maryland Research & Education Center, where she has been since 1988. That means she has seen a lot of changes in what is considered best practices for using dewormers. In addition to talking about the different dewormers and when to use them, she also gives us a little history on what used to be done and why the recommendations have changed.

She also talks about what they learned from 11 years of buck testing, as well as the best uses for fecal egg counts — and no, it’s not for determining when to deworm your goats. 

For more info on parasite research:

Visit the website for the American Consortium for Small Ruminant Parasite Control and the Maryland Small Ruminant Page.

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Other episodes on dewormers:

Want to know what is the 5-point check for parasites, and how you can use it to determine when you need to use a dewormer? Check out this podcast episode.

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For the Love of Goats! We are talking about everything goat, whether you’re goat owner, a breeder, or just a fan of these wonderful creatures, we’ve got you covered. Now, here’s Deborah Niemann.

Deborah Niemann 0:19
Hello, everyone, and welcome to another episode. I am extremely excited today to be joined by Susan Schoenian, a sheep and goat specialist from the University of Maryland Extension. She’s been with them since 1988. So that means she has seen a lot of changes in the world of worms in goats. And if you’ve been listening to me, or watching my blog, or reading my books or anything, any length of time, you know that I’m very, very passionate about this topic. Because more than 10 years ago, we dealt with complete dewormer resistance in our herd. Because I was doing everything wrong, but nobody knew it back then around me. I didn’t know it, my vets didn’t know it. So we ultimately wound up with dewormer resistance. And I don’t want to see that happen to anybody else. Because it is so heartbreaking to sit there and watch a goat die, and know that you can you can’t do anything. There’s no drug that’s going to save them. So thank you so much for joining us today, Susan.

Susan Schoenian 1:24
It’s a pleasure. I appreciate the invite. And worms are actually my favorite topic.

Deborah Niemann 1:29
Awesome. So today, we’re because we could talk about this literally all day. So today, we’re going to really focus on how to use dewormers correctly so that they work for you when you need them to work. This is like antibiotics, you know, we don’t want to use them incorrectly, because it can literally mean the difference between life and death for your goats. You need them to work when your goats really need them. So can you talk a little bit about just what is a dewormer and what does it do?

Susan Schoenian 2:08
So we throw the term dewormer out there a lot. But what we’re really talking about is a you can call it a drug and call it a chemical, you can call it a pharmaceutical, it’s a substance that is going to kill the worms. It’s either going to starve them to death, or it’s going to paralyze them. And when you look at all the different dewormers and classes of dewormers that we have, they work in a different manner. And those that are in the same group basically have the same effect on the worm. And so the worm actually develops resistance to that kind of mode of killing. So it’s fascinating how all of them all the different ones work. But like I said the whole purpose of a dewormer is is to kill the worms to expel them potentially. And we measure that usually by doing a fecal egg count. So the presumption is the more worms, the more eggs. Now, fecal egg counts aren’t that simple. There’s some some different factors involved. But essentially, that’s what we’re doing, we do a fecal egg count to estimate the number of worms that that animal has in its gut. So when we get into a dewormer, we expect that treatment to reduce that fecal egg count. And we want it to reduce that fecal egg count by 95% or more. So if I had a fecal a count of 1000 eggs per gram, which for the barber pole worm isn’t actually that high, but it’s an easy number to do math with an effective treatment should kill at least 90 to reduce fecal a count by at least 95%. That’s what we’re looking for a dewormer to do. So we’re looking for it to kill worms, we measured by doing a fecal egg count. Of course, a lot of us more indirectly measure the effectiveness by seeing that the clinical signs are relieved, you know, the animal had bottle jaw, I dewormed it that bottle jaw went away, the animal was very anemic, its eyelids were very pale. And that treatment will hopefully alleviate that symptom as well. Now that one doesn’t go away overnight. That may take a week or two to to change significant color. I might also look at how the animal is eating and behaving and that sort of thing. But that’s what that’s a dewormer is to kill worms.

Deborah Niemann 4:28
You mentioned that there are three different classes of dewormers. And that they all have a different mode of action. Can you talk a little bit about the three different classes and how they kill worms.

Susan Schoenian 4:37
So one of the most important things for sheep and goats and cattle all producers understand. Most dewormers fall into specific categories. And again, it’s based on how they actually kill the worm. So the dewormers that we typically use in the United States for goats and sheep do fall into three classes or three groups, and two of those groups kind of have sub classes. And we’re talking about modern dewormers starting like in the 1960s. There were other dewormers and there were other things that we used to treat parasites. But these are the this is the era of the modern normal isn’t. And the one thing to keep in mind is that the modern dewormers are very safe. They’re much safer than some of the things that were used in the past. So the three groups, the first group, which is the oldest group was I think they were introduced in the in the 1960s, is what we call the benzimidazoles. And so they all end in that ZOLE. We also call them white dewormers because they’re white. And so within that class, we have fenbendazole, which is marketed as safeguard. It’s also sometimes marketed as panacur. Another drug in that group that’s commonly used by goat and sheep producers is albendazole. And that goes by the trade name, Valbazan. And then the third one is oxyfendezole all which is Synanthic, not as commonly used, but as is in that group. If we look at that group of dewormers, if they’re effective, they are very good dewormers they are very broad spectrum. They kill adult worms as well as the immature worms. They’re also larvicidal so they kill the larva. They’re effective against a range of worms, particularly the strongiles of stomach, roundworms that we’re most concerned with. They also have efficacy against lungworms and tapeworms Valbazen is not labeled for goats. It is labeled for tapeworm removal and sheep safeguard is also not labeled for tapeworm removal in goats but it is effective and if it is given at a certain dose. So that’s the first group. The second group is what we call the macrocyclic lactones. And I think the first one was like in 1981, and that was ivermectin. So ivermectin, the actual name of the drug. The products would be Ivomec, eprinomectin, and Dectomax. And that two are similar drugs as ivermectin. So that macrocyclic lactone class actually splits into two what we call the avermectins, which is again ivermectin. And ivermectin, when it came out was like the next best thing to sliced bread. It was it was an amazing drug. And it actually has a lot of uses beyond in agriculture. About 15 years later, we got the first drug in in some group called milbimycin and that drug is moxidectin. It’s sold under the trade name of Cydectin.

Susan Schoenian 8:11
So, within that group, what’s important to understand is no drug in that group is FDA approved for goats. Yet we all know we routinely use these drugs for goats. But what’s important to understand is if a drug is not labeled for goats, you really need to be working with a veterinarian to use that drug. Same thing with using safeguard. Safeguards dosage, even for stomach worms is not sufficient. And so if you want to double that dose, you need to actually be working with a veterinarian because only a veterinarian has the legal right to either give a drug extra label or prescribe a drug extra label so that you can use it. So the macrocyclic lactones had those two groups, the avermectins, which is ivermectin and the milbimycin, which is Cydectin. Though the couple unique things about that group are dewormer is that they have efficacy against external parasites, of parasites that bite like lice, like mites, like nasal bots. In particular, ivermectin is labeled for nasal bot removal in sheep. The avermectins tend to be more effective against external parasites and the milbimycin Cydectin tends to be more effective against internals, there is also persistent activity inside active and what that means is that even after you’ve dewormed it, there remains some drug activity. And that’s a double edged sword because on one hand well, that’s great that is going to continue to impact parasites for say, a couple of weeks. But the other side of that is it exposes the worms to a low level of drug which makes it easier for them to develop resistance. The third group that I cannot begin to pronounce the names that we call them. So I’m just going to talk about the name that the drugs themselves just kind of two groups though, and one of them includes a drug called levamisole. And I think that one came out in the in the 70s. Levamisole used to be… remember I called the first group, the white dewormers. Well, the macrocyclic lactones, or the clear dewormers. And this levamisole used to be yellow, so it could be called the yellow dewormer, but a new company ended up it is also clear, so we can’t really use the colors. I mentioned the colors because it’s kind of interesting. If you read any of the stuff in England, they totally classify every single wormer by its color, every single one of them and when new dewormers came out, they made them another color. I always thought that was kind of interesting. So levamisole is is the primary dewormer in that group. It’s marketed under the name, prohibit or levamed. If you’ve been around a long time like me, you might remember it being called tramasole, or even levasole, and it actually needs to be marketed as both a drench and an omlet, and as an injectable. You know all of the different methods now it’s pretty much available just as a drench. Then there’s a couple of other products that are very similar to levamisole. Again, it’s kind of a subgroup. And the one that’s really important for goat producers is the one called morantel tartrate. That’s the name of the drug. It’s marketed as rumatel. It’s also just marketed as goat dewormer, you go into the feed store and it is a bag or box. And it just says goat dewormer or another label has been positive goat pellet or goat pellets. Okay, that’s the only dewormer that we feed. Okay. And it has some similarities to levamisole, this group doesn’t have as much broad spectrum activity, levamisole is really effective against lung worms. And when I talked about all of these, I’m kind of assuming they work. And if they work, we’ve got a wonderful arsenal to treat parasites. The problem is we’ve got resistance to all of the dewormers and all of the groups now.

Susan Schoenian 12:25
And that resistance varies on farm A, these drugs might work on form B, these drugs might work on farm C, none of these drugs might work. And so that’s what we’re facing now. And so we have to figure out how to use this arsenal effectively, because in most cases, there is some efficacy of these drugs on farms. The first time we use it, dewormer resistance starts maybe only point 001 worm survive, but that becomes the start of resistance. Resistance is inevitable. Just like it is in antibiotics. The only thing we control is how fast that happens. And there’s things that we can do when we use these drugs to prolong their effectiveness and to keep the worms from getting such high levels of resistance. That was a long answer.

Deborah Niemann 13:21
That was a great answer. And it was a perfect segue, you would think that we scripted this perfect segue into my next question. And that is let’s talk about all of the things that people can do. Because beyond just using them too much. There are other things that people do that reduce their effectiveness. So let’s talk about some of the things that people can do to reduce effectiveness so that people will stop doing them.

Susan Schoenian 13:48
Right. Because again, what what we do is what is what, how we’re going to prolong their effectiveness by so many different things we do. And the primary thing that’s caused resistance is just over use. We’ve just exposed the worms to the drugs too much. So frequent deworming. And then I’m going to say besides overuse, there’s been the misuse. And that one, we have to address both of them, both the overuse and the misuse. So nowadays, what we need to do is we need to get away from deworming an animal on a calendar. We used to do this when I grew up. I grew up with sheep and we dewormed them three times a year whether they needed it or not, and we dewormed all of them. And that was an accepted practice and it was sustainable back then. Okay, we need to get away from that. We used to, you know, deworming every four weeks during the summertime, things like that we need to get a bit away from that calendar based approach away from regular deworming’s the other big change is we need to get away from deworming everyone in that group, whether you call it a flock or herd, or a management group. When I was in college, I remember if you let an animal slip through, and you didn’t deworm one you had to buy everybody lunch. That was what we did you dewormed everybody, and you did it with some kind of frequency or calendar in mind. And we and again, it might have been sustainable back then it’s no longer sustainable because, and I say sustainable for animal health. It’s led to these high levels of resistance. So we need to move towards what we call a targeted selective treatment, which means treating an animal when it needs it, no treat only animals that need it, and only treat them when they need it. So that’s going to greatly reduce the number of deworming’s, it’s going to reduce the the worms being exposed to those dewormers so it’s going to prolong the effectiveness of the dewormers. And there’s two ways to go about that in the US, or at least in the southeast, we tend to focus on deworming, the one who, who needs it, I’d like to add, who would benefit from it. In other countries where they have really large numbers of animals, they kind of try to find the ones that don’t need it, you know, if they can leave 10 to 20% of them untreated, they kind of go at it from that side. So So when you’re first going with the idea of a more than a treat, who’s gonna need it. Sometimes you can actually go from what from the other side and say, you know, that, though, has just the same goal, and she’s fat and she’s five years old. I’m pretty comfortable not deworming her. So we got to start thinking about to me, you can look at it from both ways, who do you really need to treat and who can you get by who really doesn’t need treatment. So it’s a frequency of treatment and a frequency of exposure of the worms to the drug. That’s, that’s number one, I would say the next biggest problem is underdosing. So I think the goat weighs 70 pounds, it actually weighs 90, but I only treat it for 70. So underdosing exposes those worms to a lower level of the drug, which makes it easier to develop resistance. So we need to weigh our animals. Now, if you’re not a very big producer, the last thing you’re going to do is go out and buy a scale. I get that. But you can be creative. Bathroom scales, hanging scales, you can share scales with other producers. You can buy components of scales and make your own scale. Maybe your goat Association could have a scale. Or you can use weight tapes.

Susan Schoenian 18:04
There’s different formulas for weight tapes, I think there’s a chart with goat dairy goats, where you just measure the heart girth around the chest. And then they correlate that to a weight. There’s also a more generalized formula where you measure both heart girth and length to determine weight. And that’s pretty universal across goats, sheep, and cattle. So that’ll help we again, the other thing is, if you are guessing weights, overdosing. You know, we don’t like to say that in general when we talk about medicines, but the drugs are pretty safe. very safe, in fact. And so you want to make sure you don’t you greater danger in deworming animals is underdosing and not overdosing. I will give you one exception. And that is what the drug levamisole the one called prohibit or levamed, its margin of safety and goats is probably like four x four times the normal dosage. So you want to be really careful. The other thing about levamisole is it’s a product they have to mix in water, and you can mix it in different dilutions, even that’s even written on a label. So you need to be real careful that you give the proper dose for the proper dilution.

Susan Schoenian 19:22
So you don’t overdose because it’s the least safe drug, and you don’t know underdose because that’s also problematic. That shouldn’t make you want to avoid that levamisole just make sure you do it properly. So underdosing is another big cause of worm resistance. Using products that weren’t developed for your animal. Injectables were usually developed for for cattle, they should never be squirted in the mouth because that’s not the method that they were developed to be used. Not only do we not know the withdrawal period, but we really don’t know the efficacy of dewormer being supported. One of the problems with injectable products, they can be easy to give, especially for goats, but they leave a residual, an oral product clears the system. But the injectable kind of leaves a residual make, which makes it easier to develop resistance.

Susan Schoenian 20:18
But definitely don’t squirt the injectable in the mouth. The pour-ons weren’t developed for goat skin, goat hair, they should not be poured on goats, nor should they be delivered orally. Again, that’s not what they were meant for, we don’t have a clue of what the withdrawal period would be. And they’re not likely to be as effective than likely to deliver a lower dose of the drug, which again, makes it easier to develop resistance to making sure we store the drugs properly. You know, not in the, on the seat of the truck. Most of them, they don’t require refrigeration, but but store that unused amount store it in a place that’s got according to the label and the temperatures that it gives. So that that can have an effect. I’m trying to think of some of the other things that that promote drug resistance, but mostly it’s just using too much of it, and giving doses that are below therapeutic. And then also reducing the efficacy of the drug by not following the label, you know, not storing it properly. A lot of people ask, well, what about expired drugs? You know, the, the stock answer ought to be you shouldn’t use an expired drug, because you’re going to expect that its efficacy is going to decline after the expiration date. Particularly if it’s not stored, right. So I would say you know, if it’s if it’s not too far off the expiration date, it’s probably okay. But the further you get away from the expiration date, you’re going to reduce efficacy. So let’s say that the drug, when you opened, it would have been 90% effective. And it’s a year or two old and it was only 70% effective, that might have alleviated the symptoms in that animal. But you’re really doing something that’s encouraging resistance.

A strategy that we used to have years ago was that you would treat animals and move them to a clean pasture. It sounds right, it sounds like it makes sense treat them and move them and then they’re on a clean pasture. We don’t recommend that anymore. Particularly it relates to treating that whole group. Because when you put them on the clean pasture, the only eggs that are going to be deposited on that pasture are the ones that are from the worms that survived treatment. So it’s better to hold them on that dirty pasture at least for a little while or hold them inside before you put them out.

Another important aspect of preventing resistance is if you buy a new animal, let’s say you buy a new buck, don’t turn them out. For one, regardless of parasites, you should quarantine him for say about at least two weeks, preferably more like a month. And you need to do that in confinement away from your other animals. And while he’s in there, you need to treat him with multiple dewormers to make sure you kill any resistant worms. So I would probably deworm him with a drug from each class along with copper oxide wire particles, which I think are going to be covered in a future podcast. And ideally you would do a fecal a count before and after to make sure your treatments eliminated his worms and that way that new buck or doe or whatever is not introducing resistant worms to your farm we call that quarantine drenching.

And the one thing I will say I mentioned when I say the word drenching that’s when you give the medicine orally that is the recommended method of deworming small ruminants sheep and goats and goats. Since you have few products that are FDA approved. You just have safeguard Valbazen for the treatment of liver flukes and that morantel tartrate. When you use drugs extra label with the recommendation of your vet, they should always be drench oral formulation. So I when I use the word drench, I synonymously mean, deworm. And that can be another thing that contributes to resistance if you don’t have good drenching technique if your drench gun isn’t properly calibrated, so before you deworm any animal, you should draw out the treatment and put it in something where you can measure it to make sure you’re delivering an accurate dose. If you’re a bigger producer, and you’re using one of those automatic drench guns. You either want to calibrate it for each animal? Probably not. Otherwise, you need to calibrate it for the heaviest animal in the group. Another long answer.

Deborah Niemann 24:46
No, I love your answers. Now, when I dealt with dewormer resistance, I had no clue that I had a problem that was brewing until I had a dead goat and another dead goat and another dead goat. And then I read, as I started looking for answers, I read that for many people, their first clue that they have a problem with worms is a dead goat. So what can people do? Before they have that first dead goat to avoid dealing with resistance in their whole herd?

Susan Schoenian 25:22
There’s a couple of ways that you can test for resistance. In actuality, if the goat dies, it might have died anyhow, you don’t know for certain, you know, there’s a good chance if you deworm it, that died, you have a resistance issue, but it is possible that you deworm it in the deworming treatments effective and it’s still died. And the reason I say that is when we deworm, we kill worms, but we did nothing to improve the blood that that goat lost, the his nutritional status declined. And so when we deworm a goat and it dies, it’s it’s, you know, one goat, it’s still possible that the drug was effective, but the goat still died and vice versa. But nonetheless, a goat dying goats not responding seem like they’re responding to treatments. That is that sometimes is when people first think they have a problem. We we have enough history now. And enough data now to kind of say, you know, this resistance is, is it’s on every farm every go down or hazard. And it’s just knowing what the level is.

Susan Schoenian 26:29
So, a couple of things. One, we can be proactive, and we can determine if the treatment if the drug works. And there’s a couple of ways to do that. I can deworm a goat and determine if the treatment was effective in that goat by taking a fecal egg count before treatment and then after treatment. And just look at how much the fecal egg count reduction was. that’ll tell me if that treatment was effective. Now, again, like I said, an effective treatments not always enough, that goat may still need help, it might need some supportive therapy, you know, some nutritional support, he still might need that. But that would tell us if that treatment was effective in that goat. Testing one goat doesn’t tell me if I have resistance though, I need to test about 15 I want to say at least 15 at least 10 goats to see if if I actually have resistance to that drug. So one animal two animals that tells me that treatment was effective. But if I want to see if I have resistance, that drug I needed to test a lot more the power of fecal eight counts is actually in a number who do lots of them. So and the other thing about doing these fecals as I say fecal a count of fecal is of practically no value unless you get a a quantitative number. eggs per gram of feces. So a simple flotation that might be done for your dogs and cats not really useful for goats. So you always want to do a count a counts measure the poop, they measure the flotation solution. And then they there’s a special slide called McMaster slide that we can use to count the eggs. And then there’s the formula and we get eggs per gram. So that’s what we want to get. And so like I said, do a couple of goats and you know if that treatment was effective,

Susan Schoenian 28:18
do more goats to see if the there’s resistance. The alternative to doing fecal egg counts is a test called the Drenchrite. You submit a sample from say about 10 goats, eight to 10 goats. So if you have a small herd, this can work really well. And the eggs are hatched in that sample into larva. And they put that larva in these little wells. And they expose the larva to different levels of a drug. And from that single sample, they can determine resistance to all the drugs and all of the drug classes. And your first thought, Wow, that sounds great. Well, it’s not cheap, but then anything of value is not cheap. And I can’t tell you what the current price is. But it’s obviously more expensive than doing a single fecal a count. But when you think about it, if you lost a couple of goats, and they were worth very much money, or maybe they were just, you know, sentimental value, that that’s even greater at times, then that that test could be well worth it. And then that would tell you whether the drugs were effective on your farm. But the other thing that kind of relates to this topic is is what is what we recommend now because of this widespread resistance, and it’s what I call our what we call combination treatments. A combination treatment is when we give more than one dewormer at the same time. And I don’t mean to dewormer to kill stomach worms and then I give this the wormer to kill tapeworms. I mean we’re using more than one dewormer to try to kill these roundworms barber pole being the predominant one. So we’re putting different drugs to attack that barber pole worm. And so if you have a resistance in these the wormers by using all three, one for each class, you’re going to get an additive effect. So again, if I started 1000 eggs per gram in my first dewormer kills 80%. So I’ve got 200 eggs left. And then the next one kill, I’m going to do easy math. The next one kills 50%, I got 100 eggs left. And then the next one kills 40. And I’ve only got do my math, I got 40% I got 60 eggs left. So the whole idea of a combination treatment is to kill as many worms as possible. And it’s it’s a good strategy, especially when you don’t know the efficacy of our dewormers. And you and your thought might be what what happens if I do that? Aren’t the worms going to develop resistance to all dewormers? Well, if you treat all of your animals, Yes, they will. If you treat all of your animals, it is absolutely essential that you practice what I said which was targeted selective treatment, only treating the animal that needs it when he needs it. So if you have 20 goats, you know three of them got the combination treatment. So the combination treatments are only for clinically parasitize animals. And so what I mean by clinically parasitized is they’re anemic. So a FAMACHA score, what’s the FAMACHA system is a card that allows you to put a numerical score on the level of anemia. So if that animal is a four or five, or in some cases, a three, four or five, when it’s pink, light pink, or white and an eye color, we know it’s suffering from anemia, that is clinically parasitized. If the goat has bottle draw, which is that buildup of fluid underneath the jaw, very loose, not at the Adam’s apple, but directly under the jaw, that’s clinical parasitism. Some of the other signs of clinical parasitism are a little bit harder to differentiate from other problems. You know, when you have a thin goat goat that’s losing body condition, you have a rough hair coat, you have a potbelly, those things are a little bit more subjective, but they can also be signs of parasitism. And when we look at all that stuff, collectively, we can determine Yes, that goat is clinically parasitized. And it warrants a combination treatment, combination treatment would be to give the most potent drug from each of our dewormer classes in the benzimidazoles, or white dewormers that would be albendazole, which is Valbazen. In the macrocyclic, lactones, the most powerful drug would be moxidectin, which is cydectin, and then that third group, which I can’t pronounce levamisole, which is prohibit or limit the amount. And you would give each of those drugs at the proper dose, one after the other preferably a separate syringe, you would not mix them. Now, I’m going to add that each of those drugs and the recommendation I just gave you requires extra label drug use. And yes, you should work through a veterinarian.

Susan Schoenian 33:13
But that’s what our parasite consortium, the American Consortium for Small Ruminant Parasite Control, excellent info, that is what they recommend, is to get a combination treatment to these clinically parasitize animals, essentially what we’re trying to say is don’t deworm your animals a lot, but when you do it, give them a big gun, that’s going to be the most effective treatment. So that one that’s that pathetic goat that’s pale and thin, we’re going to give him a big gun. If he needs supportive therapy, you know, medicine wasn’t enough, he needs extra nutrition, we’re going to do that too. But we’re going to kill as many worms as we can. But that old fat girl over there that wether chewing his cud just do nothing, or never, we don’t need to give them medicine if they don’t need it. So give them when they need it and give them a big gun. And again, work with the veterinarian so that you’re in compliance with these recommendations.

Susan Schoenian 34:12
I don’t know if I’ve mentioned it yet, but so goats only have the few dewormers so when you look to extra label, you look to the sheet products because goats are more like sheep. And most of the research is going to be more analogous than it would be for other species. Um, so we want to use the drench products is what we want to use for them. Oh, long answers.

Deborah Niemann 34:36
Can you talk a little bit about the role of refugia in controlling worms on your farm and start with just telling us what is refugia?

Susan Schoenian 34:47
Yeah, refugia is a new term that a lot of producers haven’t heard of. And basically a refugia is just a worms that are in refuge. They have not been exposed to dewormer so that Could be larva that’s out on the pasture, or it could be the worms that are actually still an animal because we’re always going to remember the worms in different places. We focused our everything on the animal. Oh, do we control parasites by giving the animal something. And I think there’s been a paradigm shift to say, you know, maybe we need to be a little bit more focused on when the worms are not inside the animal. And that’s where refugia comes into play. And every parasitologist, well, not everyone, but most of them will tell you that that’s the primary strategy for dealing with dewormer resistance is to maintain refugia on the pasture. So every time I send an animal through that chute, or send an animal at that gate, and I did not deworm it on creating refugia, that lamb, that animal is going to deposit eggs onto that pasture, and those eggs are going to potentially develop into larva. And those larva those worms will still be susceptible to that dewormer treatment. So when we talk about all these strategies to to reduce the exposure to the dewormer, what we’re trying to do is increase refugia. So increase worms within the system, that have not been exposed to the drugs, and are still susceptible. And and that’s kind of where our strategy is aimed at is having it’s having that refugia. Like I said, it’s it’s a new term for a lot of producers. But it’s just, you know, again, it’s keeping trying to keep worms susceptible to the drugs, versus the old days when our goal was just to eradicate worms, which was which really, we think about is not a good goal. You know, worms, just like bacteria, they’re a natural part of the animal system of our systems. And the goal is not to get rid of them, it’s to have them at a level that it does not impact animal welfare, animal production, but not to get rid of them. Because you know, most of they have actually found that animals that are immune to parasites, you know, what those are also the ones that are more immune to foot rot. There’s a research being done at West Virginia University. It’s with sheep. But I think, again, there’s similarities, they are finding that the lambs with that are more resistant to parasites actually have higher survivability. But parasites are important, but they’re really wrapped up in immunity. So so we’re not trying to get rid of them, we’re trying to control them. And, and one of our strategies nowadays, is that refugia of maintaining it on pasture, allowing those worms to survive, because they’re not causing any problems to that animal. So we’re allowing them to survive so that we can maintain the effectiveness of the drugs, so that when we got that one that needs to dewormed, we can deliver an effective treatment. That’s the goal, right, we need to be able to help the animal that can’t handle it, we need to do things to reduce the number of animals that can’t handle it, we need to reduce things that that require us to deworm animals. But in the end, we still need something to give to that animal because certain animals are more susceptible. Certain years, there’s more problems. So we need to keep those drugs in our arsenal, we need to employ those strategies, that that allow us to continue to use them.

Deborah Niemann 38:22
Okay, so just to kind of quickly summarize, we are we’re not going to deworm our goats, because you know, it’s January or because it’s breeding season, or for any random reason, we’re only going to do the ones that really need it. And we’re going to determine that based on their FAMACHA score, which is like the color of their eyelids. If it’s too pale, it means they’re anemic, which is a symptom of barber pole worm, and their body condition score, because their body, they’re they’ve lost weight, they’ve got diarrhea, things like that they’ve got symptoms, basically, they’re sick, so we need to treat them with a drug. What one thing you have not mentioned yet which so many people this is a really popular question, and I know your answer to it. And that is what’s the fecal egg counts supposed to be when you decide to deworm a goat?

Susan Schoenian 39:15
Fecal egg counts are one of the very useful things that we have in managing the health of goats. However, their best use is three things. One is to determine, already talked about it, how effectively the dewormer is and more specifically, to determine whether you’ve got resistance to that drug or to the level of resistance had that drug. That’s one of the best uses of fecal egg counts. The second best use of fecal egg counts is to look at differences, genetic differences in animals. You all have them in your herds, animals that never need dewormed and those that do and what we’d like to do is we We’d like to be able to identify the animals that are more resistant to parasites. And we do that with fecal egg counts, because fecal egg counts, again, they estimate the worm burden. So they estimate the level of infection in the animal. And so that’s another really good use of them. You could also do fecal egg counts to determine the level of pasture contamination. You notice I didn’t say do a fecal a count to see if the animal needs deworm. I didn’t say fecal egg counts, by themselves, are not a really good tool for determining whether an animal needs to dewormed. And the reason is, again, they’re an estimate of the worm load. They’re not always highly correlated. We did a buck test for 11 years, and we never had really high correlations between fecal egg counts, and FAMACHA scores. So clinical side is never very high. They’re just if you have that information, in addition to clinical signs, certainly you use that information. And certainly if you did a fecal egg count and it had like zillion eggs per gram, then you want to deworm it because it’s contaminating the pasture, you want me to define as a zillion probably. So I would say if you think an animal needs to dewormed, you need to look at it and get your hands on the animal. You need to do that FAMACHA score. Highly recommend you take a course if you haven’t already. You need to feel the body condition score you need to look for bottled jaw, you need to assess the hair coat you need to assess the fecal consistency.

Susan Schoenian 41:47
If you’re not sure, deworm it. What we’re trying to get away from is that massive deworming everybody and deworming all the time. If you’re not sure it’s okay to deworm. Do a fecal a count before and after to see if the treatment worked. And one of the challenges with with the accounts is what egg count you do format. When you do an egg count, you don’t even know what worms they are. You just know you can separate out tapeworms and coccidia but you can’t separate out the three major roundworms. You can’t say it’s barber pole worm, because the eggs all look very similar. So you really can’t do that. And there’s a lot of limitations with them. So So what So basically, I’m just saying it’s don’t use it as your only criteria. But if you happen to have it, or you haven’t have a microscope and want to do it to that, that’s, that’s fine. I would say if you have a microscope, do the before and after to see if the treatment was effective, but go ahead and deworm that animal, if it’s showing clinical signs. Um, if you had a really big farm, people say, Well, you know, FAMACHA, it takes too much time, body condition, scoring takes too much time. But there’s ways to implement those practices, even on big farms, in a lot of other countries in the world where they don’t have the as much of the barber pole and they do rely more on fecal egg counts. With the barber pole worm, which is the predominant parasite in warm moist climates so good. But in the United States and in Canada, um, you know, we got it, we got an instant tool for helping us make that decision. If I’m in a part of the US or part of the world where it’s more what I would call a scour worms, the ones that tend to affect digestion and cause diarrhea or before can cause diarrhea, you know, then I think fecal accounts might be a lot more useful. But for the barber pole worm there, you know, it’s a very prolific egg layer. If a buck had a count of 2000, and our buck test, he still qualifies as one of the best bucks of tests. So Wow. You know, and so what’s high for one parasite is not high for the barber pole worms. So focus on the clinical signs. And like I said, if you’re not sure then deworm it, do a before and after fecal a count to see if it worked. And, and don’t, you know, if you are worried about how your animals are doing, don’t collect their fecals and do their fecals, get them in a pen, get him in the chute and look at him and handle him. That’s what you do. If you’re not sure, put them on a scale. Because there is some effort to see if we can use average daily gain as a criteria. It’s used in the places where the barber pole worms not the predominant parasite. We always remember the barber pole worms gotta be nuke thing. I mean, it’s it’s a killer, it’s deadly. It’s a lot different than the worms that just kind of run them down and cause them to go slow and have poopy butts. You know, we got to be real more careful on that one. But we’re trying to see if average daily gain can help. I know in the research that we do at my research center, if I have an animal that’s a FAMACHA three so it’s pink. I might not ordinarily deworm it but if it lost weight, I will go ahead and we don’t just look at FAMACHA we use what’s called a five point check, which is FAMACHA body condition, jaw, back or tail to look for scours and also the nose for nasal bots, goats, we tend to more look at hair coat than the nose. So we use that to make a decision. And then if we also have a weight when we have a weight, if they lost weight, we’re going to go ahead and deworm. So fecal egg counts are very useful, but they’re probably best used for what I mentioned, determining drug efficacy, determining the difference in resistance for animals, and maybe monitoring pasture contamination.

Deborah Niemann 45:32
This has been so wonderful. I am so appreciative of you joining us today to talk about this because there’s still so much misinformation out there about it, I still, you know, every, at least every few days, I get an email from somebody who, you know, tells me that they did one of those things that is, can lead to dewormer resistance and is not particularly helpful for treating worms. So hopefully, lots of people will be able to hear this and start smarter deworming practices. Is there anything else that you want to say before we sign off?

Susan Schoenian 46:08
Yeah, be careful where you get your information. Facebook’s not a good place. Now. I see a lot of times people say what do you think I should deworm with? And nobody can answer that question for you. Because everybody’s farm is different. So you need to know what’s you know, your situation be completely different. So be careful where you get your information. We do a website again,, which is the website for the American Consortium for Small Ruminant Parasite Control a lot of a lot of information on there, a lot of fact sheets, but get your hands on your goats, that that’s, you know, get your hands on and look at them. You know, just don’t look at them in the field from a distance and say, oh, they’re not doing very good. I’ll go collect some poop, but actually do FAMACHA scores, do body condition scores and realize that nutrition has a big role in that as well. You know, be be aware of and at least, like she said, drug resistance is a huge issue. You could think you’re doing everything right and go needs the world. And if we didn’t deliver an effective treatment, the FAMACHA system does not work without an effective treatment. It does not and so if you’re going to just give one drug you need to know which one works. But we would recommend that you that you use combination treatments to give that that one that’s that’s clinical.

Deborah Niemann 47:28
Well, thank you so much for joining us today. I know this is going to be very helpful to a lot of people. And I hope you will come back again sometime because there is so much more that we can talk about with worms,

Susan Schoenian 47:41
I would be happy to and it’s been a pleasure. Like I said I enjoy talking about worms because as an extension person as well, as somebody who’s been doing research has been a real focal point of our program. We did a buck test for 11 years and the 90% of the focus on that was parasites. And besides trying to identify bucks for the consigners will learn an awful lot about everything. And goats can be goats aren’t the same as sheep. There’s similarities, certainly, but they are not the same. And it’s always important to appreciate that. Yes.

Deborah Niemann 48:18
Thank you so much. And that’s it for today’s show. If you haven’t already done so be sure to hit the subscribe button so that you don’t miss any episodes. To see show notes you can always visit and you can follow us on Facebook at See you again next time. Bye for now.

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8 thoughts on “Using Dewormers Correctly”

  1. Great content!
    I would be interested to find out if there is a good source of info on the average parasite load for herds in the US and possibly nroken down by breed, region, and time of year. When she mentioned the buck with 2000 FEC and he was one of the best, I was blown away! If one of my BGs had a count that high I would be flipping out! I’ve had one doe who is a crossbreed who had a 4600, which was a shock because she exhibited no outward signs, I just caught her in a random testing. I thought that was a horrible load! I dewormed because I didn’t want her contaminating my pasture. With my fullblood BGs a count of 1200 is high to me because normally their counts are in the 400-800 range.

    • It was not just one buck that had a count that high. She said bucks with an s over 11 years of research. That is interesting that your doe had such a high count and zero outward signs. That’s exactly what she was talking about — no correlation between FEC and a goat’s condition.

      I’ll ask Susan if there are any studies that have compared breeds.

  2. Hi, I have a doe with very pale eyelids. I didn’t check FAMANCHA, and actually lost one of my favorite does at the beginning of the week. I had already started treatment on her but it was too late. The fecal showed they had a high egg count and I dewormed all with Valbazen. It’s been a week since I dewormed and the one that has pale eyelids still has soft poop. Now I did add in alfalfa hay, so I’m not sure if the soft poop is from that since it was becoming solid, or if the dewormer isn’t working. I called the vet but they said I need to deworm 10 days later and then bring in a fecal 10 days after the second deworming so it’s too soon to tell if it’s working. I wanted to get your thought. Should I deworm again and this time use a dual deworming approach? I am also doing an anemia treatment (Red Cell and 30cc if ACV and water mix). On top of that treatment I have been using an herbal dewormer daily.

    • Sounds like your vet does not have updated information on parasites. You should NEVER deworm all goats in a herd. That simply moves you towards dewormer resistance. And if a goat died after deworming, that may mean the dewormer did not work for some reason. Did you use 2x the dosage on the label? How many times have you used Valbazen in the last year or two? Have you dewormed all the goats previously?

      If the doe is not better within a week, then the dewormer did not work. If you use Valbazen again, definitely use 2x the dosage on the label AND use another one with it, such as ivermectin or Cydectin (moxidectin). If you buy a tube of the horse dewormer, it is almost strong enough for goats, so just round up on the weight when dialing up the dosage.

      If you’ve got the herbal dewormer, you can use it because it won’t hurt, but it’s not helping. I’ve done before and after fecals, and those herb blends do NOT kill worms at all. Using 1/2 ounce pure wormwood only kills 50%.

      Doing another fecal at this point is only going to tell you that the Valbazen didn’t work. If your doe is still anemic, she needs to be treated. Dewormers are drugs that are used to treat symptoms — and anemia is a very serious symptom. Here is more info on dewormer resistance:

      Here is the link to sign up for my e-course on parasites:

    • Most people incorrectly assume that you double the dosage of all horse dewormers, which is incorrect because horse dewormers vary in strength from one drug to another compared to goats, cattle, and sheep. For goats, you always double the cattle or sheep dosage, except for levamisole, which is only 1.5x. Horse dewormers are more complicated.

      Quest dewormer for horses is 2% moxidectin, whereas cattle moxidectin is 1%. Goats need 2x the cattle dosage of moxidectin, and Quest is twice as strong as cattle moxidectin, which means that Quest is the correct strength for goats. When using horse dewormers, you always need to compare the strength of the medication to the cattle dosage and do the math accordingly. I know it’s tough to eyeball those weights on the tube for goats, but don’t worry if you give a little more than needed. You really do not want to underdose because that leads to dewormer resistance quicker.


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