Baa's and Bleat's - The AASRP Podcast
Baa's and Bleat's - The AASRP Podcast
Using Drugs in Dairy Goats
*We want to hear from you! Send an email to DairyGoatExtension@iastate.edu and let us know where you are listening from, how you are involved with the dairy community, and if you have any questions that you'd like our experts to answer in a future episode!*
Today we are talking with Dr. Virginia Fajt -- a boarded veterinary clinical pharmacologist from Texas A&M University -- about the in's and out's of how to use pharmaceuticals appropriately in dairy goats.
Topics discussed include: Appropriate drug selection for a small ruminant; withdrawal times, how they are determined and where to find them; what is FARAD and what do they do; accidental inappropriate drug or chemical exposure protocols; how meat and milk processing facilities prevent accidental drug residues from reaching consumers; safeguards for preventing treated animals/milk from leaving the farm.
Helpful Links:
AASRP Guidance for Antimicrobial Stewardship
http://www.aasrp.org/resources/AASRPantimicrobial3F.pdf
Databases for searching for approved drugs:
https://animaldrugsatfda.fda.gov/adafda/views/#/search
https://dailymed.nlm.nih.gov/dailymed/
Federal regulations about extralabel drug use:
https://www.ecfr.gov/current/title-21/chapter-I/subchapter-E/part-530?toc=1
FDA resource for veterinarians about extralabel drug use:
Food Animal Residue Avoidance Databank for estimated withdrawal intervals for extralabel drug use:
Details about how withdrawal times are established for approved drugs:
Compliance policy guide about using feed additives extra-label in minor species:
This podcast is sponsored by the American Association of Small Ruminant Practitioners as well as USDA National Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Program, Antimicrobial Resistance grant # 2020-04197.
Questions or comments about today's episode can be directed to DairyGoatExtension@iastate.edu
Hello, I'm Dr. Michelle Buckley from Iowa State University's College of Veterinary Medicine. Thanks so much for joining us on Voz and Bleats, sponsored by the American Association of Small Ruminant Practitioners. Just a quick note before we get started. This work is also supported by the USCA National Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Program, Antimicrobial Resistance Grant No. 2020-04197, which funds my research on improving antibiotic stewardship in dairy goats to assure food safety and milk quality. As always, if you have any questions about any of our episodes, please email them to dairygoatextension at iastate.edu. I hope you enjoyed today's show. And today we have Dr. Virginia Fate joining us to talk about how to use drugs safely in dairy goats. Thanks for joining us, Dr. Fate. Can you give us a bit of background information on yourself to get started?
Virginia:Sure. Hi there. My name is Virginia Fajt, and I'm a veterinarian and a clinical pharmacologist. I work at Texas AM University and I've been involved in teaching pharmacology to veterinary students as well as other undergraduates and graduate students. I collaborate with clinical faculty here at Texas AM on various kinds of research projects related to drugs in animals, particularly in food-producing animals. I went to veterinary school at Auburn. I didn't grow up on a farm. I grew up in kind of a rural area. And I got interested in sheep and goats actually before I went to vet school and kind of continue that interest through vet school. I did a food animal internship at Kansas State University. I was a clinician there for a year, and then I did graduate work in clinical pharmacology, antibiotics and cattle. And so I've been interested in food-producing animals throughout my veterinary career. One of the things that clinical pharmacologists sometimes focus on is the regulatory aspects of drug use, drug approval, legal and illegal drug use, choosing drugs, making decisions about drugs, antibiotics, antibiotic resistance, and those kinds of things are some of the things that I've been interested in. Awesome.
Michelle:I think we have a very similar, we've been on a very similar path, or at least mine starting out kind of like yours did. So I hope I can be as as helpful as you are. So I guess as a clinical pharmacologist, you're the perfect person to talk to and helping other practitioners make wise choices in how to choose which drug they need when they're dealing with a specific problem. So what's kind of a good process or thought process to go through when deciding which drug to use once we've diagnosed a problem? And then how would that maybe be different for goats as a minor species versus cattle as a major species?
Virginia:Yeah, that's there's a there's a lot wrapped up in there. Um one of the things that that I like to think about when as veterinarians are making decisions about drug is drugs is um a systematic approach to making choices about drugs, antibiotics, or any other type of drug, and starting out thinking like, what is what is my therapeutic goal? What is it that I'm trying to accomplish with this drug? Obviously, that's going to stem from whatever you diagnose the problem is, or even if it's symptomatic sort of treatment. And if it's specifically if it's an antibiotic, one of your first questions should be do I know what bacteria are likely to be present in this um in this infection? Um, do I know which drugs are likely to be effective against that type of bacteria? Do I know that the drug will actually get to the site of the infection? This becomes really important when you talk about, for example, dairy, goats, and mastitis. Mastitis um uh uh causes issues as because we're um we're the concentrations of drugs in the udder are different than they are in other parts of the body. Um they're not necessarily correlated directly with plasma concentrations or tissue concentrations. And so it's just another um piece of information you need to think about if you're approaching, in particular, mastitis. Um, and the thing about food animals is you're always layering on the decision making about which drug to use. You're layering on are there restrictions, um, whether they're federal restrictions or restrictions related to the product consumer or the buyer of your product. So a dairy or a creamery or a um a dairy along those lines, you're gonna want to be thinking about not just does this drug work, is it effective in the animal, but is it legal and is it likely to cause a problem that relates to public health? And that's where most of the drug regulations come from. They relate to safety in humans. So the some of the challenges with working with food animals, particularly small ruminants, is that many of those animals are not considered food-producing animals by their owners, or they are kind of cross-purpose, right? They're food animals, they're milk goats, but they're also they have names. Um, you know, they're they're more like pets. Um, but in the eyes of the law, in the eyes of the USDA, the FDA, um, the uh milk producer co-ops and so on, um, those are food-producing animals. And so the laws that apply to other food-producing animals apply to goats regardless of the intention of the producer or the owner as to what's going to happen to those goats at the end of their lives. So it's important to recognize that it doesn't matter that there are minors, so-called minor species. Um, you mentioned um uh major species versus minor species. That's a definition, that's a federal regulatory definition that has to do with uh the number of animals there there are and their importance in the food supply and in uh the the populations in the country. So the major food-producing animals are cattle, uh, swine, chickens, and turkeys. Um, and so sheep and goats are are minor species, but all essentially all of the laws apply to them. There are a couple of minor differences in, or actually one minor difference in one regulation, but generally speaking, goats are food animals, and so any of the regulations that say anything about food-producing animals and restrictions on drug use apply to goats regardless of their lifestyle or what their goals are in life.
Michelle:So Okay, so we first need to diagnose the problem as veterinarians, and then we need to consider what drug we can use based on the regulations that's going to accomplish our therapeutic goal. And sometimes those regulations can get a little bit sticky, but that's where folks like you and I come in. Well, hopefully me someday, if I can ever get through boards. Um, but so you know, there's always clinical pharmacologists out there, right, ready to chat with practitioners that might have questions about this type of thing. Do you deal with that a lot?
Virginia:Yeah, and there are a number of clinical pharmacologists that um that kind of focus on food-producing animals. Um, and certainly um uh veterinary practitioners who um pay attention and who are going to their continuing education and have their um and you know keep up with what's happening in the profession should also be familiar with those rules and regulations. Hopefully they learned about them in school or in their you know, postgraduate training or mentoring or the continuing education hours that they get. Um, all of the food animal veterinarians that I know that are clinical veterinarians, like internists and surgeons who work at veterinary teaching hospitals, are all familiar with these regulations and um and so kind of help students, veterinary students learn how to make those decisions appropriately. So uh when a a couple of colleagues of mine, other clinical pharmacologists, Dr. Brian Lubers and Mike Apple at Kansas State, I've heard them say the questions you should be asking yourself when you're thinking about using a drug and food-producing animal is um is it legal, is it effective, and is it safe? And so that legal question, oftentimes when you're thinking about a food-producing animal, you might as well start there because if it's not legal, it doesn't matter if it's effective or safe, right? So effective that that that um fits with what we were talking about before, which is does it address the therapeutic goal that I'm interested in addressing? And then safe is about safety of the animal. So we want to make sure that there aren't significant adverse effects that might be important in a particular animal. And then is it safe to consume products from that animal or when does it become safe? And I think maybe that's um what you want to talk about next, which is what does that mean? That that leads to what many producers are familiar with, and veterinarians certainly are familiar with, which is withdrawal times. So the withdrawal time is the time after a drug is administered that you must uh prevent the product, whether it's milk or meat, um, from entering the food supply. So we talk about milk withdrawal times or meat withdrawal times. So depending on what product you're talking about. In the case of you know, dairy goats, you'd be talking about milk in particular. How long do I need to withhold the milk from that animal after I use a drug? That's the withdrawal time. Withdrawal times are for drugs that are approved for a for a particular use and in a particular species of animal at a specific regimen, and that becomes really important. So regimen is the dose of drug, milligrams per kilogram, or something along those lines. The route that I'm administering the drug, am I giving it intravenously, intramuscularly, intramammary? Um, the frequency, is it am I giving it once or twice a day or um four times a day? And then uh duration is how long am I giving it? Is it am I giving this once? Am I giving it for five days, and so on. So dose route uh frequency duration, that's what makes up the regimen. And so the regimen becomes really important for withdrawal time because the regimen determines how much drug is in the animal for how long, and that um that will have an impact on how long that the products from that animal need to stay out of the food supply. Um, and depending on whether it's milk or meat, there are different ways of determining it. Um, but there those are experimental methods that happen if for a drug that's approved, those um studies would be performed prior to the drug being made available for purchase. And the the uh regimen that's on the label would be administered to the to the to a group of animals, and then samples would be taken over a period of time. Some mathematical and statistical models would be used to um determine um at a particular confidence interval for a 99% of the population when the concentration of drug in the product is below a particular amount. And that particular amount is called a tolerance. And so that's actually a legal term. So tolerance and tolerance is determined by a much more complicated methodology that I don't but yeah. If we have show notes, we can put you, we can give you a link to that. But the tolerance has to do with an acceptable amount that a human could consume over, you know, a period of time and be safe. Because when you administer a drug to an animal, there are always going to be a few molecules of drug left. Um, and those uh at below particular concentrations, those amounts are gonna be safe. Uh the dose makes the poison, um, as Paracels said many millennia ago. And so um it's possible to have a very low amounts of drug that are completely safe and safe to be consumed, and that's what a tolerance is all about. And so what we're trying to establish is with some confidence, if I treat any animal that's that's on the drug label with the regimen that's on the label, how long do I need to wait? Um, and with confidence, when I put that product into the food supply, will it be safe because it's doesn't have drug above the tolerance.
Michelle:My my boss, Dr. Gordon, loves to give the example that if you know you handed someone a $20 bill and then had them do a drug test, the sensitivity of these tests that we're talking about that we're using on animals would allow you to detect cocaine in that person's system just because they handle the $20 bill. They're obviously not under the influence of that drug, but it's just we are able to get so sensitive. Um, but you can handle cash your whole life and not have ramifications from cocaine usage. So just to kind of give people a real world example, maybe that's a little more relatable. Is that have you heard that one before from Dr. Gordon?
Virginia:Yeah, that's a great one. Um, you know, the ping pong ball in the in the swimming pool, right? I mean, the the the grain of sand really in the swimming pool. So the sensitivity, the accuracy of the tests um can detect parts per million, parts per billion, parts per quadrillion. Um, and just because we can detect a small number of molecules of drug doesn't mean that that drug is at any concentration that will have any effect um in in an animal or any effect in a person that consumes the product because it's it's low enough levels that um the just because it's detectable doesn't mean it's not safe. And so that's a really important point. Um no, there there will there will never be zero drug when you administer a drug to an animal, but it will be below any level that that's actionable or um unsafe for human consumption if the withdrawal time is followed appropriately. So a withdrawal time is um established for uh drugs that are approved by the FDA Center for Veterinary Medicine, and the withdrawal time is on the label. So if you are using a drug exactly as what's on the label, then you need then you can follow the labeled withdrawal time. The challenge with any species, but particularly with um with goats, is that there really aren't that many products that are approved for use in goats. And so oftentimes veterinarians are selecting drugs appropriately, selecting drugs that are approved in other species of animal. Um, or maybe they're approved for goats, but they're approved for a different indication, um a different disease. And so when you use a drug in a fashion that's called extra label, um, then you have to think differently about withdrawal time. So defining extra label, it's it's a very simple definition. It's using the drug in any way that's not on the label. So if the drug is labeled for uh intramuscular use and you administer it subcutaneously, that's extra label. If you, if the dose on the um label says five milligrams per kilogram and you give it 10 milligrams per kilogram, that's extra label. If the drug is approved for cattle and you use it in goats, that's extra label. So it's anything that's not on the label is considered extra label. Now there are lots of ways to be extra label. There's the uh, well, it's approved in goats and I'm gonna use it for a slightly different indication, or it's approved in dogs and I'm gonna use it in a goat. So there the all of those things are extra label. But there are differences in terms of how we interpret whether that's a legal extra label use or not. So we'll we'll get to that a little bit later. Uh, but it does become challenging sometimes to interpret um, you know, what extra label means. But the um the point about extra label and withdrawal time is if you use a drug in an extra label manner, then the withdrawal time that was on the label doesn't apply anymore. And so you need to you need to gather information. And luckily in the United States and some other countries, um, we have access to FARAD, the Food Animal Residue Avoidance Data Bank, that's um supported by um your tax dollars, but um, it's a USDA supported project at several universities that over the last 30 years have developed a database of information about the pharmacology and pharmacokinetics of drugs that are drugs and pesticides and other compounds that um animals can be exposed to, food animals can be exposed to. And so if you are going to use a drug in an extra-label manner in a food-producing animal, you can contact Farad to see if they can help you estimate what the withdrawal time should be. So they use their extensive knowledge, their proprietary database, their algorithms for statistical analysis of pharmacokinetic data to say, all right, so this drug is approved in cattle and you want to use it in a goat. Here's what we know about how this drug works in goats, here's what we know about the pharmacokinetics in goats, the drug disposition, concentrations over time, etc. And therefore, we think that our our best um scientific estimate is that the withdrawal time in a goat for this should be 45 days, whereas, say, in cattle it might be 30 days. So extended withdrawal time is typically what Farad will provide a veterinarian with. So that's the important thing about Farad, is they their job is to help veterinarians make good decisions or manage situations where there's an inadvertent exposure of a food-producing animal to some product. So a lot of veterinarians think about Ferride as about drugs, but they also will help you manage, for example, if a if a group of animals got into an agricultural chemical, for example, and you'd like to know is it, do I can I when might I be able to market these animals? Um and sometimes Farad will have information that they can help you essentially establish a withdrawal time for whatever that chemical is. You wouldn't typically do that, but um, it's it's a toxicity situation as opposed to a um, you know, a firm uh a therapeutic situation.
Michelle:Essentially, if it's not on the box, you need to ask Farad, and um, and Farad should be able to give you some guidance based on the research that they have accumulated and that uh postdoc students like myself are doing and and things like that. So even if drugs aren't labeled for something, it may still be an option. You just need to need to ask. If something happens accidentally, you're like, We can, you know, we gave ivermectin to a lactating dairy cow. Oh man, well, what do we do? You need to call Farad and they can help you sort it out.
Virginia:Yeah, that's right. I think the other thing I want to I would say about call uh contacting Farad about withdrawal times is um if you if you contacted them 10 years ago and got an extended withdrawal time for a regimen that you um that you use um fairly often, you should call them regularly because um over time uh research uh accumulates, we get better information. The tests that are used to detect drugs change as well, maybe become more sensitive. Um the Food Safety and Inspection Service may revise the way that what they test for, how they test, when they test. Um, and so things change over time. So those withdrawal time estimates that come from Farad are not, shouldn't be thought of as static. They could potentially change over time. They might get shorter, they might get longer, they might um uh uh uh some people have had the experience where they contact Farad, and Farad says, we can't give you a withdrawal time that will keep this product safe, and we recommend that you don't use that drug in that animal because for for for a number of reasons. Um, pharmacology, there um, and and legal um ramifications.
Michelle:And I definitely have heard Farad employees say these are not meant to be used in protocols or anything like that. These are a case-by-case recommendation because they can be updated so frequently. So that's a good point to highlight. Um to kind of move a little bit away from Farad, um, I know there's a list of drugs that are there's a list of regulations, right, that govern how we use drugs in food animals specifically. And on that list, there are a few drugs that we absolutely cannot use in food animals or uh in lactating animals. So can you just kind of name those off for me real quick, just so they're on people's radar if you're gonna start working with dairy goats? Yeah, yeah.
Virginia:So let let me let's clarify first of all. So the the federal regulations that govern extra-label drug use in food producing, well, extra-label drug use in general, and then specifically the the section of that that applies to food-producing animals, um, describes drugs that cannot be used in an extra-label manner in food-producing animals. Um, and so that that's kind of a key phrase is that in an extra-label manner, because there are some drugs on that list that are labeled for some food-producing animals, but they would be illegal for use in other food-producing animals. So um it's a good example about goats, um, which is that the drug um batrel that contains the fluoroquinolone and rofloxicin, there is a uh formulation of that that's approved in cattle for respiratory disease. But fluoroquinolones cannot be used extra label in food-producing animals. So that drug cannot be used in a food animal that's not on the label. So that drug cannot be used in goats, for example, because they are considered a food-producing animal and it is not on the label. But it can be used in cattle if you use it as what's on the label. So it's a little bit of a um, I wouldn't say confusing, but it's sort of a fine point that we say you should never use enrofloxicin in in goats, but it's because you can't use them extra label and there are no labeled enrofloxicin products for goats. So effectively it's illegal to use them um in goats, but it's the extra label use that's technically the illegal piece of it. So it's a little bit of a, I know I sound like a lawyer, right? So, but but um that that is the case, right? So so drugs that are il illegal for extra label use in food-producing animals, which would include goats, um, include things like clenbuterol, dimetridazole, metronidazole, um nitrofurizone, um furozolidone, um, the fluoroquinolone antibiotics, so enrofloxicin, ciprofloxicin, difloxacin, um, the glycopeptides, vancomycin is the main one that some um some people might have heard of. It's a human used um drug, usually mostly used in humans, but it is it's in the category of glycopeptides. So, not that anyone would probably use those in a food-producing animal, but it is illegal, it would be illegal to do that. Um yeah, yeah, it's expensive, it's hard to administer, you know, etc. Um the uh sulfonamides can't be used extra label in dairy cows, lactating dairy cows. So um there some people think that it maybe is of sort of higher regulatory priority when it comes to extra label uses in other dairy animals, so dairy goats, but technically it's not illegal to use them extra label in dairy goats. It's only illegal to use them extra label in dairy cows. Uh, but to me, that would suggest that maybe you should be cautious when you're doing that. Um, the other one that's um illegal for extra label use in dairy animals is um uh a non-steroidal anti-inflammatory phenylbutazone. Um, some of you may be familiar with its use in um horses, but that's illegal for use in lactating dairy cows as well. So that's another one that, you know, if I was trying to be cautious, I would use a different NSAID if I was interested in using one in a dairy goat. Um the one that is a little bit confusing is particularly when it comes to small ruminants, is the extra label use of cephalosporins. So there is uh cephalosporins are included on the list of um extra label uses that are illegal, but it's kind of a fine-tuned illegal. So extra-label use of cefapyrin, which is a mastitis product, is not illegal. It's okay to use cephapyrin extra-label. So that means you can use it in dairy cows in a regimen that's different than what's on the label, and it also means you can use it in dairy goats. Um, the other thing about the cephalosporin extra-label use um ban is that it doesn't apply to minor species. So it doesn't apply, it only applies to cattle and swine and poultry. It doesn't apply to um sheep and goats. And so uh drugs like ceftiopher, which is a cephalosporin, um are not illegal to use in goats. Um, even though there's a it sounds like there's a ban on extra-label use of cephalosporins, there is in major species of food-producing animals, which are cattle, swine, chickens, and turkeys. So we kind of have a nice little loophole there when it comes to small ruminants that we don't have in other places, um, and which is useful because we don't there aren't a lot of drugs that are approved. So we are doing a lot of extra label use um in some cases for some things, because their drugs are just not approved for those small ruminants. The best approach if you're a veterinarian is to is to contact Farad before you choose a drug. Um, and if you are um if for some reason uh a use occurs that you might not have chosen yourself or that another veterinarian chose, or um or there's an inadvertent exposure, somebody makes a mistake, um that's a really good time to call Farad to find out what um what the best withdrawal time would be for, even if it's an illegal, um, it turns out to be an illegal use. Um getting that information for Farad will really help you when it comes to having the conversation with the producer or the state board or whatever it is to um say, well, I did the best I could, there was an inadvertent exposure, I got information from Farad, we withheld the animal for this prolonged period of time. Um, and so we've you know we've managed the situation.
Michelle:Awesome. I think it's important to remember that you're not bothering Farad. If you contacted them, you know, multiple times a week and you're trying to do the right thing and you're new to to dairy goats or are just working on food animals and you you just want to make sure you're doing the right thing, you're not bothering them. It's their job, they love doing it, um, and they want to help educate people. So it's never the wrong choice to call them.
Virginia:That is an excellent point. Yeah. I mean, they have they have um highly trained individuals that answer phones and um and hear questions, and they're questions that they get regularly that then they they have access to that information that they've given out before. And so they're not necessarily starting new with every single question that comes across. Um, so yeah, no, if you're if you're not sure, contacting them is definitely the best approach. And in in most cases, they will get back to you very quickly. So um, I mean, you're not gonna call them and get an answer on the phone, but and they would prefer anyway that you um that you email or go on to the website to contact them, but generally it'll be you know within a day or two that you'll have the answer that you need. So yeah, it's never wrong to contact them.
Michelle:So, and then if something inadvertent happens, a drug that was given, you know, that you didn't recommend or was, you know, the selection was incorrect and you realize it after the fact, um, your license isn't gonna just automatically explode, right? Like there's there are some things that we can do to mitigate that getting into the food supply. Um, but what happens if a drug is given illegally or um or we do something that we shouldn't? What are the ramifications? What's the worst case possibility? And what does that mean for that animal and and for our license and our producers?
Virginia:Well yeah, so let's say you don't know about it, or um maybe somebody misreads the label and um sends an animal to the um to the harvest facility, or they send milk to the um milk producer um to the creamery or whatever, um, without knowledge of that the withdrawal time wasn't followed, or something else happened, or there was a drug exposure that wasn't recorded properly, um then the those facilities, those food-producing facilities, whether it's they're slaughter plants or or milk producers, creameries, and so on, mural processors, um, they will routinely test um when with milk, every tanker of milk is tested. With um with meat, it's a uh statistically random sampling that's um that's performed of uh samples of carcasses to test for multiple drugs. And so depending on whether you're talking about milk or meat, um for milk, essentially every tanker full of milk is tested for um particularly for um for antibiotics, um, but but it's essentially all milk gets tested in the United States if it's going to a commercial processor. Now, if you're if you're milking at home or you're milking for um a co-op or something like that, um or for a you know a small what uh what do they call those um cooperatives, producer small groups of um anyway, um yeah, like uh yeah, then then then that might might not be tested. And so that's a separate conversation about where do you get your your um milk from as to whether that's but the commercial milk that you buy at the store, um it's gonna every tanker full is gonna be tested for um for drugs and um for meat. Um a statistically uh random sample of um carcasses will be tested, along with um carcasses if they don't look, if they look unusual to the inspector in the slaughter plant, if there are obvious injection site um reactions, or if the animal has some appearance of, I mean, if it looks, if the if the carcass, if the animal looks like they're sick, they won't ever go into the food supply at all. Um, but they also might then get tested to see if they also have residues. But um grossly contaminated meat doesn't enter the food supply at all. Um but if there's some suspicion um about you know that the animal looks like they might have recently had an illness, they would be set aside, tested separately. Um the carcass wouldn't be wouldn't enter the food supply until the test results came back, and so on. And so that's how that those are the ways that our food supply is protected from. It's the um the end of the the veterinarian makes a good choice about using drugs, follows regulations. The um they use drugs that are approved in either in the species or in some other um species of animal or people for that matter. So they use approved products, um, they follow withdrawal times or get um extended withdrawal times from Farad, and then the the um the last sort of pillar is the sampling at um at harvest time. So there's a whole series of events that that all together help protect the food supply. So we have safe, wholesome product in the end.
Michelle:And it's the USDA that supervises um the monitoring, right, in in slaughter plants uh and in the testing facilities with the dairy. Um and those are USDA trained inspectors and veterinarians that are at every every processing plant that sells food to the general public, right?
Virginia:Yeah, that's right. So the the only um the the if you are not purchasing commercially manufactured um products, that's where the the sort of the last pillar might not um if you are buying, if you're if you are uh drinking your own, if you're drinking milk from your own animals, obviously that's not happening. Um and so other you need to make other make sure that other things are um happening appropriately, that you're working with a veterinarian to make good choices about drugs, that you're not consuming um the milk when there might be um drugs in the in the milk, that you follow a withdrawal time, you're just not selling the milk, you're consuming it. So, yeah, those um so that that last um you know gateway of protection isn't there, but it um but all the other protections are there. And there are ways for um individual, um they're not approved for those ways, but there are methods of testing product to try to see if there are contaminants, um if there are drug enough drug left in there to cause a problem.
Michelle:So yeah, that's a good point. And I I know I've heard some um especially especially dairy practitioners that I've been around um will recommend that their clients actually test the milk in their bulk tank before they ship it, or they'll test their hospital string or animals from their hospital string. They'll dilute samples from those animals, test them uh with a an on-site milk test um to make sure that they're clear before they get put back in the milking string to make sure that we don't have any contaminated product going um going to the processing plant. And obviously, with more of a dairy background, I I know a lot about the milk, but how about the meat side? Is there like an equivalent on-site um test that you can do to evaluate meat residues?
Virginia:There there are some people that um that have used or advocated the use of um testing methodologies where you would test urine to look for um drug concentrations. The challenge with that is I mean, it's a it's an interesting approach because you're you're um you're addressing the problem before it becomes a problem, right? You're you're trying to identify animals that might you know test hot if they go to a um slaughterhouse. But those the the drug concentrations in urine don't exactly mirror drug concentrations in the rest of the animal. Um, and that has to do with physiology and the way urine is produced and and so on, which is beyond the scope of this discussion right here. But um, but urine concentrations here, yeah, urine concentrations don't correlate exactly with tissue concentrations, they don't correlate exactly with muscle or meat concentrations. So um if there's uh if you test a sample of urine and there happens to be a detectable amount of drug in it, it may be that there actually isn't enough drug in the tissues to be a problem. Um we just don't have um we have some information. There's some um scientific information about the pharmacokinetics and urine concentrations and so on, but um the urine concentration can be so variable, it's challenging to trace it back to how much is actually in the in the tissues of interest in the animal. If we know what's happening in the urine, we there's a pretty wide range of possibilities of what could also be happening in tissues. So it's one approach. Um, in some ways, it's a conservative approach, right? If there's any in the urine, there might be some in the animal, but it's also possible that a even if there's some in the urine, there might not be a detectable amount in the meat. And so it's an approach that people use and sometimes use successfully, um, particularly on a on a group level, right? Maybe you're not trying to identify a specific animal. Maybe you something happened and there was some sort of inadvertent exposure. So now you're trying to figure out when is the best time to harvest those animals. Um I I don't think they're in they're commonly used. They are used in the livestock show industry, also a completely different conversation. Um, but I think that's the challenge, is urine concentrations don't correlate well with tissue concentrations, with meat or muscle concentrations. And so um I I I don't know what to do with a negative or a positive test in urine. It's challenging to know what that really means.
Michelle:That makes sense. I guess I could see how people would get there because from my pharmacology training thus far, kidney is one of those target tissues that will sometimes be evaluating along with liver and muscle. So I could see how you could get to urine from kidney, but it's important to remember that the kidney's job is to produce this ultrafiltrate called urine, which is probably gonna have higher concentration than what's happening in the rest of the tissue. Is that fair? Okay, okay. So then I guess my my big question is what happens if my client does have a positive test for a drug residue um in meat or milk? Am I just gonna get brought before the board? Are they taking my license away? Or is my client gonna lose their animals? What happens?
Virginia:Yeah, it's gonna depend on um, you know, whether it's meat or milk. So if there's a positive milk um sample, then that tanker full of milk is going to be destroyed. Um it's OA will never enter the food supply. What happens to the producer of that milk, though, depends very much on where they're selling their milk, or if it's the first time or the third time that that's happening. Happened. So, you know, if it's the first time and upon investigation of what happened, it turns out that a mistake was made, a record was um was um was not recorded properly, or something along those lines, um then it's likely that um the creamery or uh processor might just say, you know, don't do that again. Um and you're on a, you know, we're we're we're paying attention to you, but you know, it's all good. But if it happens multiple times, then there's that there's certainly a chance that that um someone would stop that produ that processor would stop buying milk from you. So that's certainly a possibility. Uh the same thing on the meat side. The USDA maintains a public list of um producers um that have who have um had violations that have had residues, positive residues, more than once in a 12-month rotating period. And so uh once you violate, once you have violative residues multiple times, then it's again it's possible that you will that they will not purchase um your product anymore, your animals anymore, um, and so on. Um as far as what what happens to the or what could possibly happen to um in terms of penalties, again, if a producer presents animals that are unsafe, which is what we're talking about, um, multiple times, they will potentially get inspected by the um FDA or the field office in their in their location. They will their records will be inspected. And um if there's a veterinarian of record for that farm, that veterinarian will be um interviewed and also possibly inspected. Um, and so it's not that one single violation triggers all of those things because you know mistakes happen. Um and so that's that's not really the approach of FDA or uh FSIS, at least in my experience. Um but but you want to prevent those things from happening and you don't want to have them happen multiple times because then you will get uh the hammer will drop and there will be inspections, you'll get letters from the FDA that say you know you violated all these things, and you know, if you don't clean up your act, then then we're gonna we're gonna um shut you down or we're gonna prevent you from selling your animals ever again, and so on. So there's a it's the pattern as opposed to the you know individual mistake or violation. So I think it's important that you know you stay vigilant, you don't nobody wants um any of those things to happen. The other um point to make here is that when there is a violation, like a residue shows up in meat or milk, um, for the general public, it's important to remember that if those tissues, if that meat or that milk isn't contaminated, it doesn't enter the food supply. So um the the system works when we identify residues, because the system is designed to find those residues and then eliminate those products from the food supply. So that's a just important point to make there.
Michelle:Very important point at that. So um, so what kind of resources are available for practitioners? I especially I think of like small animal practitioners that are getting asked to see, you know, little hobby farms or potentially even, you know, bovine vets that are getting asked to see dairy goat um type like larger production setups. Um everybody's goal is food safety. We want to keep the food supply safe. Um, and so what are some good starting resources and and maybe some good backups that people can have in their arsenal to make sure that we're all accomplishing this goal?
Virginia:So I'll put in a plug for ASRP here because the American Association of Small Room and Practitioners has um fairly recently developed guidelines on um uh about um prudent drug use and about um antibiotic um stewardship, antimicrobial stewardship, so helping to prevent um antibiotic resistance, mitigate its um issue. So I I mean I would start there if you're thinking about um uh someone who is not familiar with small ruminants, what are the things you should be thinking about as a, particularly if you're not a um if you don't have other food animals in your practice. I mean you kind of are getting accustomed to working with animals that are food-producing animals. But even if you're accustomed to working with food-producing animals, there are you know some differences um as it relates to small ruminants um or smaller farms versus you know large dairies. Um there are some great quality assurance programs out there. You can search you know, dairy goat quality assurance and most extension. Um I've seen multiple extension um services that will have some really useful guides to residue prevention, um, prudent use of drugs, things to remember about recording um drug use and um I mean all animal health events um and so on. So those are some places to start. Um AASRP also has um continued education sessions at multiple meetings. They partner with AABP, the American Association of Bovine Practitioners, to present sheep and goat and deer served CE continued education at conference at their annual conference every year. There are often sheep and goat sessions at other conferences. Um ABMA has AFRP sessions as well. So those are other places too. I mean, you your veterinarians are accustomed to doing continued education. And so if you are uh moving into a new realm, if you're a small animal practitioner and you're starting to see some small ruminants in your practice, then um those are good places to learn some new things about or get some reminders about what's different about ruminants, what's different about goats, what's different about um drugs used in food animals, and so on.
Michelle:I think as a newer vet, having only graduated five years ago and didn't really have a lot of small ruminant experience coming out of school, but wound up doing predominantly small ruminants when I was in practice. One thing that I noticed is that my fellow uh go in sheep veterinarians were incredibly welcoming. It was not, I was worried people would be like, oh no, we don't need more of you, or you're taking our job. No, there's plenty of work to go around, and people are so excited that other people want to work on small ruminants. So I hope that other uh practitioners out there are not intimidated by the community because it's been very welcoming in my experience. So jump right in. All right, well, I have a couple of little case scenarios here for you that might just help kind of put a lot of what we talked about today into a more clinical perspective for for folks that are still listening thus far. Um, so my first one is what do I do if a client is asking me for oral chlorotetracycline for their goats? Can I do that? Yeah, that's a good question.
Virginia:Um, the uh extra-label drug use regulations, federal regulations say that um drugs that are approved for feed additives cannot be used extra label. So um drugs in or used in or on animal feed cannot be used extra label. And chlorotetracycline, the only way it's available is is that is as a feed additive. So technically speaking, chlorotetracycline shouldn't be used in um in goats because it's not approved for them. However, um there uh there is uh what's called a compliance policy guide from the FDA, which is uh kind of a special circumstances publication that says technically this is illegal, but as long as you follow some of these other guidance, and I'm I don't want to go into all the details on that with this, but um we can provide a reference for that as well, um, about that that that you can um you could potentially prescribe. It's not really technically a prescription, it's a feed or a uh veterin feed directive that you would provide for chlorotetracycline to be used. Um part of it has to do with you have to use the product that's as it's um formulated, it needs to be formulated for a uh similar animal. So if it's a cattle product, it could potentially be used for um goats. The the technicality is though that that is still illegal. It's just of um what's sometimes called low regulatory priority. And the FDA has said, we will not prosecute you for this illegal act as long as you follow these, you know, guidelines. Um and so it's kind of a it's sort of a loophole in a sense, but um, but it also is one that doesn't make it a legal use, it just makes it not likely to be prosecuted. So it's a some people are uncomfortable with that. So so one avenue is to not is to not use the that loophole. Um I hesitate to call it a loophole, that makes it sound hinky, but uh, but it's a it's a reasonable thing to do, and people do it regularly, but um, but that's the thing to understand about chlorotetracycline in particular because it is a feed additive, that feed additives are um in a in a different category. So we talked earlier about specific drugs that are illegal for extra-label use. Um this is kind of a general category of drugs. So all feed additives can't be none, no feed additive can be used in an extra-label manner. Um, the other um drugs that shouldn't be used in an extra-label manner are drugs that are not for therapeutic purposes. So the extra-label drug use laws apply to animals that are suffering or where death might um suffering or death might occur if they aren't treated. So for therapeutic uses, production purposes, so like reproductive manipulation or feed efficiency types of uses, those drugs can't be used in an extra-label manner, or drugs can't be used in an extra-label manner to accomplish those things. So that's a that's just a little um uh kind of going back to a little bit about what the regulations. So gotcha.
Michelle:That makes sense. And you know, there's a whole other discussion about whether oral antibiotics are even effective in ruminants. So um, aside from the legality, that would be a consideration as well. Um, but basically you you might be able to do it, but there are a lot of other things to think about, and and there's some hoops to jump through along the way. So it's a discussion to have, certainly. Okay, perfect. Um, so my second scenario is um how about those pesky little goat kids that get diarrhea? Can I give them some metronidazole? I know that's really handy with puppies, especially. So will that be okay if I if I do that?
Virginia:So metronidazole is one of those that's on the list we talked about earlier, which is drugs that are that can't be used extra label um in food-producing animals, and there is no metronizole metronidazole approved for goats. And so this would definitely be an illegal use. So metronidazole would not be illegal to use in cattle or goats or sheep or any other food-producing animal because there are no metronidazole products that are approved for any food-producing animal in the United States.
Michelle:All right. Hard no on the metronidazole. Got it. Perfect. Okay, uh, the next scenario is my client told me um their go-to pink eye treatment is topical nitrofurosone powder. Is that okay since it's not a parenteral use?
Virginia:Yeah, and uh, it's kind of a reasonable question, right? The when I think about drug use, I think about giving drugs systemically, intramuscularly, intramammary, whatever. And if I'm just putting a little bit of drug topically, um, isn't that okay? And nitrofurzone would be another drug on the list of drugs that should never be used extra label. There is no approved nitrofurosone for food-producing animals. So, nitrofurosone, no matter how you use it, so the lit, the the regulation doesn't say systemic use, parental use, it says use. And so any use uh of those drugs um that's extra label would be illegal. So this also would be a hard no.
Michelle:Okay, I like the easy answer. Just no. Um so my last scenario is uh actually something that I saw in practice. Um, I had a goat patient um with a uh mastitis that cultured resistant to every intramammary antibiotic that we could find or that they could test for. But it was sensitive to fluoremphenicol. And so my client did some research and said, Well, there's a product for fluorimphenicol in food-producing animals. It's called new floor. Can we just infuse that into the udder or could we give it systemically? Um so what would you say about that?
Virginia:That's another great question. Um, and there's a couple of things wrapped up in this question that maybe aren't just about legality that that maybe might be helpful to think about. Um so the first is that the product, New Floor, and there probably will be other fluorophenicol generic products available, um, is approved for respiratory disease in cattle. And um, and it is systemic, and the formulation of the product is designed for giving subcutaneously to animals. So the pH, the the excipients, the additives, and so on that makes up that drug formulation are designed for a specific route of administration. When you give a drug by a different route of administration, especially like something that's such a major difference subcutaneously or intramuscularly versus intramammary, um, it becomes really challenging to predict what will happen to that formulation, to that drug when you give it um in the mammary gland. Is it going to be damaging? Is it are there some things in that product, not the not necessarily the drug, but the other other things that are in the formulation that are potentially damaging to the um to the udder, which is not what you want to do. You don't want to damage the milk making machine, right? Like that, that's probably not something you want to do. Um, and so in the absence of really good scientific information that um that demonstrates that that product is safe and that you get concentrations of drug where you want them to be, I'd be very cautious about doing that. That's number one. Number two is um in this, what I'm reading in this question is that you got a culture and susceptibility report. So you sent the a sample of milk to the lab, they grew uh a bacterial organism, and they did antimicrobial susceptibility testing on it. And the panel that they used might have been a mastitis panel, and most of the drugs on the mastitis panel are drug, are um uh are designed to demonstrate the effectiveness of the drug when it's given intramammary, not systemically. There's a lot more con there's a lot more complication or a lot more details of that that we don't really have time to get into. Um, but I wouldn't be confident that if the susceptibility panel said it was susceptible to fluorophenicol in vitro, that that would actually correlate with successful outcome in my patient if I give the drug intramammary. So there's a lot of steps in between where I have a lack of information about correlation with the diagnostic results, as well as not not knowing for sure about the formulation and whether it would actually be safe and also useful and provide effective drug concentrations. So there's a couple of things wrapped up in there. The the as far as whether it's legal or not, um, I think you know, if you have demonstrated resistance, then that's that seems like a reasonable rationale for using a drug extra label because you can't use other drugs that are labeled because there's antibiotic resistance. Um, but but the uh but then you would also have to have information from Farad that um or somewhere else where you would um have use enough scientific information to provide an extended withdrawal time because not only are you using a drug that's not labeled, you're also using a drug that's not labeled in a completely extra-label manner, in a way that we might not be able to predict what happens to drug concentrations in the milk or in the meat for that matter, how much gets absorbed, how much stays in the milk, how long does it stay in the milk, and so on. So there's kind of several aspects of that scenario that I like that that really you know allows us to talk about a lot of different things, but it also is very complicated.
Michelle:I mean, and my thought process was it's it there's no goats on the label, it's not labeled for intramammary use, um, and we have no idea on a withdrawal. So we we did not end up doing that. But it was an interesting question that came up. Um I I think we ended up just uh drying that quarter off and decided not to mess with it anymore. So um, but yeah, it can get pretty tricky, and there's a lot of convoluted ways to get to answers sometimes, but um I hope that folks got a lot out of uh out of our discussion today. I think you had some really important points. Um, and luckily, if they have maybe this is a lot to take in at once, people can come back and listen to it a few times and um certainly reach out to their nearest clinical pharmacologist or or Farad if they have further questions. Absolutely. Did you have any final thoughts for today?
Virginia:Or No, I think we taught we touched on some really important things. Um and you know, we talked a little bit about you know, thinking about um is the drug effective? Um we didn't talk very much about adverse effects, but that's always in every veterinarian thinks about what are the potential side effects of a drug, adverse effects of a drug, because I want it to be more effective than it is harmful. That's my goal, right? Um, and then um a lot about legality, yeah, about legalities, and that gets it can get really complicated when you start layering in milk, meat, uh FSIS inspections, um, formulations, extra label drug use regulations that are federal. What's the veterinarian allowed to do because of the practice act in their particular state, medical records, quality assurance? There's a lot of um a lot of moving parts here. And so it can get the conversation can get really complicated. So I appreciate the opportunity to talk about all of these things.
Michelle:Awesome. Well, thank you so much for your time. I hope we didn't intimidate folks, but um, if if people have questions, they're certainly welcome to reach out at dairygoatextension at iastate.edu. That's our email address here. Um, and we can get questions out to Dr. Fate if you have them specifically for her. But um, thank you so much for your time, Dr. Virginia Fate down at Texas AM. And I'll look forward to seeing you this year at the annual conference.
