Editor’s note: Second in a three-part series.

It’s not unusual to blame a drug when an animal fails to respond to treatment, but often the failure is in identifying the sick animal in the first place. But identifying and pulling sick animals or animals that are on the verge of sickness is a blend of art and science that on today’s busy feedlots can be hard to accomplish. Making the problem worse is that all cattle pulled don’t always need treatment.

Scott MacGregor, DVM, MS, Livestock Consulting Services, Idaho Falls, Idaho, has come to the conclusion that at least in northwestern feedlots, if you pull an animal in fewer than nine or 10 days, the case fatality rate can increase by three. “Those could be stale auction calves,” he says. “They’ve had prior disease exposure, incubating or fulminating the sickness as they come into the feedyard and shipped to us from a background of right at 14 days when they’re breaking. Or, they’ve had a history with infection, and then they’ve been treated with one of the new-generation antimicrobials and survived it, whereas maybe 10 to 15 years ago, they wouldn’t have. So, they’re smoldering something that’s fairly well-advanced, and if we pull them on day six, they just can’t take the trip. Very often their numbers will be significantly worse.”

Shawn Blood, DVM, staff veterinarian at Hitch Enterprises, Guymon, Okla., agrees. “When pulling cattle early in the feeding period, you’re going to have a higher case fatality rate and a higher chronic rate. Our numbers would suggest that our case fatality rate is going to be twice as high with cattle pulled at fewer than seven days. And our chronic rate would flow right along with it.”

“And that may be fairly conservative,” adds Doug Hilbig, DVM, Hilbig Veterinary Services, Lakin, Kan. “I think the first seven to 10 days is when the problems come on -- rather than your pulls that are late in the disease process.”

Criteria used to pull and treat cattle also can vary. Kynan Sturgess, DVM, Amarillo, Texas, isn’t a fan of using a strict temperature criteria to treat cattle. “We talk about training issues and getting people to recognize disease and pull cattle when they’re sick. I see just as much of a problem, if not more, with over-zealous people who want to pull way too many cattle. You may see nice treatment results at times, but it’s not an accurate depiction of what’s going on.”

Sturgess adds that time management is also a factor. “You could weigh every chronic you re-started and weigh them again in 30 days. You’d probably do a better job of sorting through and getting rid of things, but we don’t take that kind of time. We’ll go through and visually sort those pens and pull some cattle out.”

Antibiotic selection

Robert Sprowls, DVM, PhD, Texas Veterinary Medical Diagnostic Laboratory, Amarillo, frequently isolates multiple pathogens, both viral and bacterial, from chronic animals. The type of pathogens you’re dealing with makes a difference in antibiotic selection, treatment regimen and management of sick animals. Because of that, suggests MacGregor, “We might start off with a narrow-spectrum product, then go broader after that.”

Blood believes we have a good arsenal of antimicrobials to use. “We focus on a program where we’ve got the bacterial component up early, and then as they get more chronic, it gets a little more complicated. It gets back to management -- the timeliness of the pull and what happens next. Antibiotic selection and execution are important.”

When an antibiotic is first used, for the most part sensitivity patterns show very little resistance to the major bacterial pathogens, but resistance develops as their use continues. “It appears the sensitivities on some of our newer antibiotics are not fading as rapidly as with some of the earlier products,” says Sprowls.

Hilbig surmises that the sensitivities may not be fading as rapidly because the increased number and type of antibiotics available today may not be putting as much resistance pressure on an individual antibiotic.

Appropriate dosage is another factor in how well a product may work against pathogens in the long term. Sturgess refers to Blondeau’s work on antimicrobial resistance. “We need to start looking at drug dosages from the standpoint of what their propensity is to select for resistance and take a harder look at his data and theories and decide if we are dosing products appropriately. We can dose them to an efficacy level, but some of the research is starting to indicate that’s not good enough. Obviously, you’ll run into problems with toxicology in some respects, and you can’t do that, either.”

Not knowing what calves have been treated with during their pre-feedlot life is a problem. “Many of these calves are not from the big northern ranches where they’ve never been treated,” says Hilbig. “They are from the South and small sale barns. A higher percentage of them have been treated, and those pathogens have selected for some resistance to certain antibiotics. It would be nice to know the popular drug in that region because we may not want to use it on them here. They get along real well if we can use drugs they’ve not had or that haven’t had a lot of antibiotic pressure.”

How much should cost figure into antibiotic selection? With a fluctuating cattle market, that may “just depend.” It appears in most situations the newer-generation antimicrobials are being used, says Hilbig. “We may complain about the cost, but we use them. It doesn’t take long to say ‘this is not economically feasible.’ I think we find a level where we can maximize profits, which means we’re getting a return on investment. They are expensive, but they do some good.”

MacGregor says when cattle prices are high, it’s a good time to use the higher-priced products. He cites a paper given several years ago at the Academy of Veterinary Consultants about when it is appropriate to use high-priced products. “It concluded that it’s appropriate to use them when fat prices were high and morbidity was high.”

Unfortunately, MacGregor explains, people have tended to use high-priced products in ways where they won’t get a good return. “As prices have escalated with newer products, it has put pressure to take those new products and, first time out of the box, stick them in a third-line treatment, which is a lousy place to test a new drug, and most of them do not get off to a good start. We’re putting them in really rough cattle that have probably been treated twice already. And then we’re disappointed when re-pull rates are high.”

MacGregor suggests if the industry could study post-therapy response, there may be a shift in using the higher-priced drugs more effectively. “In other countries where feedlots own their own packing plants, they have been able to get yield data back from the packing houses post-therapy, and their conclusion is that the higher-priced products have a higher performance yield and carcass yield that helps pay for the difference in price,” he says. “If you take a $20 product and a $3.50 one, I can build a cheaper therapy program by first-line treating with the $3.50 product. However, I may be giving up 12 pounds of average daily gain of weight gain by not using the more expensive one, which cleans the lung deeper and quicker, and you get more maintenance shifting to gain and get a better choice carcass. We don’t know the answer to that question, but it would be important to learn because if it’s true, it changes the whole paradigm of therapy. It’s something we need to study.”

Hilbig agrees that could be happening. “That’s maybe some of what we’ve seen with our metaphylaxis. We see cattle that gain better and take care of some of the subtherapeutic diseases, as well.”

MacGregor notes that metaphylaxis studies have been done, but not treatment studies. “They are doing it overseas and retrospectively looking back from the carcasses.”

Treatment issues

There are also treatment issues with hospital pens. As Sturgess indicates, many feedlots want every inch of pen space filled with feeder calves and don’t want to allot more space to hospital pens. “It’s always a fight for pen space because they want to feed more and more cattle. In many of our yards, pulls are going right back to the home pen the same day. We don’t keep them around the hospital because it always comes down to the point of making a decision: Where’s the best environment I can find for that animal? Unfortunately, there are times where the only place to put them is back where they came from. It may not be the best place, but it is under the circumstances.”

Hilbig agrees that sometimes treated cattle are safer in their home pens because they have less exposure to other sick cattle and are less crowded and less stressed than in the hospital pen. “But that’s a pen issue. Where we deal with them best is a place that is bedded with more pen space. When you only have 50 to 75 square feet per animal in the hospital, it’s a wreck. The pens are wet, and it’s a poor environment for the animal. Because of antibiotics, we think we don’t have to do some of the management things, and then we’re disappointed in the result.”

Are antibiotics used as an adjunct to labor management? They can be, but in the right circumstances that doesn’t appear to be all bad. “In antibiotic selection, one of the main things we’re looking at is labor management,” explains Blood. “We want the pen riders to focus on riding pens instead of helping to shuffle cattle around. The long-acting antibiotics have sure helped us significantly in that regard. There’s no way, in our facility, to get the manpower to run cattle through the chute every day to treat them with a daily antibiotic. We use more metaphylaxis and more long-acting antibiotics in our treatment program often because of labor management.”

Do pulled cattle always need to be treated? MacGregor doesn’t think so. “We try to build programs called the ‘no treatment group,’ so if they don’t fit the case definition, they don’t get antibiotics. That way we don’t feel we’ve lost anything but time and labor.”

Evaluating treatments

Treatment response may be harder to get your arms around. Obviously, an animal that is right back in the game with its penmates is a treatment success, but there are gray areas in response. Appearance, temperature and weight gain are all factors, as well as other subjective measures. For a chronic, Hilbig might look at how far it is behind the pen. “If it’s substantially behind the rest of the pen, it may not go back to that home pen. We’ll keep them in a long-term recovery system.”

MacGregor likes to pull treatment response rates every Friday. If the treatment response rate, based on 14 to 21 days, goes over 20% failure, “We’re going to start looking for another antibiotic to put in,” he says. He adds that years ago, many veterinarians wanted to have a consistent approach to antimicrobial regimens and go through the whole season on that regimen. “We sure don’t do that anymore. We’re changing drugs all over the place.”

Sturgess agrees that treatment regimens are changed on a much more frequent basis. “If anything, we may be just trying to create a moving target so we can help manage resistance development better.”

MacGregor believes that every time we give an antibiotic, we’re selecting for a group of bacteria that are not susceptible to that antibiotic. “Whether they are a pathogen or a problem, we don’t know. But I do find myself changing and starting to look more at changing on a more frequent basis rather than waiting until we get to the point that we’re not satisfied.”

Blood doesn’t like a lot of seasonal switching, but there have been some situations where the regimen has changed mid-stream, usually due to cattle-department personnel. “We might have one feedyard where essentially the syringe-fillers don’t have a lot of experience and knowledge to critically evaluate treatment regimens on a daily basis. They are good at following orders but lack critical decision-making knowledge. In another feedyard, we have a really experienced treatment technician who we give more leeway and it’s a lot easier to evaluate what’s going on in a pen or feedlot basis with him. It’s a people and execution decision more than an antibiotic choice.”

Re-treatment moratoriums

Drugs need a certain amount of time to start working and have a significant impact on disease, though treatment crews and veterinarians can get impatient and want to either re-dose or change drugs. The concept of having a “moratorium” in place before going to another treatment or drug choice is gaining momentum.

“I’m a believer the moratoriums are probably of value,” says MacGregor. “It’s taken some training and risk-assessment. The data would indicate we can reduce relapse rates, and we also reduce the time commitment for the pen rider because he’s re-pulling fewer cattle. We’ve recommended a seven-day moratorium with all sustained-release products, whether they are extended-duration seven or nine days.”

MacGregor adds that the South African feedlots he consults with have used moratoriums on all sustained-release products for six years. “Their relapse rates have been like ours, about 15%, lower if you can get them through that five-day period. But, the management has to buy into that seven-day period.”

Blood says that in his protocols the moratorium will be five to 10 days depending on what is being used. Most of the clients Sturgess has go with three to five days maximum -- though he admits some feedlots make it a hard and fast rule, and others change depending on what the manager decides.

Hilbig adds that it’s easier to get clients to follow moratoriums on bigger cattle, and harder on high-risk and small cattle. “It’s hard to get management to buy into that, especially on the lightweight cattle, because they can see that you can run the cattle back through, and they are doing other things when they come back through anyway.”

Hilbig notes that sometimes you can get management to hold off on the antibiotics and come back through with a supportive therapy instead. “On the outfits that have the really tough high-risk cattle, it’s hard for them to stay out seven days. The cattle are too valuable, even though some of our costs of treatment are really high. On the other side, we’ve had some issues where people just go back in there too quickly and you’ve got a ton of money in those cattle in a short time period. In those situations, it’s easy to put on a five-day wait.” 

This information is from a Bovine Veterinarian roundtable sponsored by Pfizer Animal Health.

Next issue: Preventing chronics, employee training, marketing and economics


BQA AND WITHDRAWALS

Drug treatment means running the risk of residues. Especially in animals treated multiple times, recordkeeping and identification are critical. Most of the feedlots Kynan Sturgess, DVM, works with are set up to cease treatment on an animal once it reaches a certain point, then a dated tag is put in the animal’s ear to indicate the date the drug will have cleared. “That doesn’t mean they won’t still check the records on that animal when he does go out as a railer,” says Sturgess. “If we have a buyer, we make sure he sees the sheet with all of the data.”

When people want to buy cattle before they have cleared, Sturgess says they must sign off that they understand that the animal is not clear. “That makes things pretty fail-safe,” he says. “Plus, it helps them evaluate some things as they’re sorting through cattle and deciding what to do with them. They can look at that date and have an idea if this is an animal they can go to town with.”

Doug Hilbig, DVM, says sometimes owners of the cattle want to take them back and re-start them at their own location, but they have to sign off that they understand the withdrawal time. “We have several that go out in that circumstance. It makes it easy for everyone to understand when we use the tag with the withdrawal date.”

Things are a bit more strict at Hitch Enterprises. Shawn Blood, DVM, says no animal leaves the feedlot until it has met the meat withdrawal time. “Our cattle manager has to evaluate the withdrawal report on every one of those railers, and he has to sign off on it. So if they’ve still got drugs on board, they don’t leave the feedyard.” Blood says those animals also wear a railer tag with the last day for drug withdrawal indicated.

Railer tags that indicate the date the animal will be clear of antibiotics can help the feedlot and potential buyers make further decisions.


ANIMAL WELFARE AND CHRONICS

Chronic feedlot cattle present an animal welfare challenge. “It’s a challenge to train our personnel to make sure those cattle are not totally forgotten,” says Doug Hilbig, DVM. “You do have to get management into it so they understand that there’s an advantage to trying to do supportive therapy, which isn’t very expensive. It’s an animal welfare issue.”

Hilbig says a calf that’s not eating or moving around a whole lot isn’t necessarily a hopeless case. “With the value of these animals today, there is a value in having somebody do something with that calf -- run him through, give him electrolytes or anti-inflammatory drugs. If you lessen the welfare issue, it’s more likely to return money.”

When to say when

One of the hardest things Scott MacGregor, DVM, MS, does is determine when an animal should be put down. “We decided we needed a medically and economically sound system,” he says. “If you follow the system, at least you feel you’ve done something appropriate for the animal. If he’s at a low level of existence, then it’ll make you feel better about doing it.”

How do you determine just what the level is? Robert Sprowls, DVM, PhD, believes body condition is an important indicator. “If they’re sick and in poor flesh -- and these are the ones the animal welfare people are zeroing in on -- the truth is they have to overcome illness and gain weight at the same time,” he says. “The colder the weather, the less likely it is that they’ll make it. That really puts them at a disadvantage.”

A sick animal is in a catabolic state, which suppresses the immune system. If an animal is in good flesh while in a catabolic state along with trying to overcome disease, it may be able to sustain itself. “With any disease issue, if you go into a catabolic state, you can’t lose all of your muscle mass at the same time,” explains Hilbig. “If you have nice, dry pens in the springtime, they do well. But it’s different in the fall. There’s a point where the environment overcomes what you’re able to do for them.”

It’s not hard to make the call to euthanize when a calf is down and can’t even get up with help. “We put feed and water in front of them, and they don’t stay there for a long period,” says Hilbig. “If it gets to the point where they’ve been lying in their own swill, there’s been a break in our system, and it’s inhumane at that point.” If the animal is a brainer that is down, Hilbig has it put in a nicer environment and tries to treat it. After a certain period, if it’s not better, it probably isn’t going to recover.

“When it’s getting cold and an animal is down and not eating, there’s no hope. He doesn’t have the energy to get up and fight the disease process,” says Hilbig. “We know it’s wrong. I don’t think anybody has a problem with euthanizing those animals; with some, we have to decide how far are they from that? It’s difficult for me to say, ‘Let’s euthanize that one when he’s still up and drinking and eating and walking around.’ But when you suddenly get six inches of snow and the temperature drops -- those are the ones that usually succumb to it.”

Shawn Blood, DVM, says that animal welfare awareness is increasing. “In our pork operation at Hitch Enterprises, our packer can come in to do a welfare audit and to look specifically at some of the animal welfare issues, including when and how we euthanize. Our company, in general, has a heightened awareness of animal welfare issues. Management probably doesn’t think about it a whole lot except when evaluating our guidelines. We critically evaluate it primarily from a pain and suffering standpoint and then from an economic standpoint.”