A lot of factors go into feedlot health product selection, protocols and evaluation, such economics, research trials and diagnostic tools. For the most part, veterinarians are the main drivers who influence feedlot health programs. “That’s what they hire us for,” says Tom Portillo, DVM, Progressive Veterinary Services, LLC, Amarillo, Texas.

Evaluating feedlot treatments

“Economics also plays a part,” Portillo adds. “If there are pharmaceuticals out there with rebate or sale or ‘buy 10 get one free’ options, we have to help them decide if it is a viable option or if the value may not be there. Also, given the class of cattle, we need to decide if we can get the same job done with a less-expensive product.”

Monitoring and testing

Before making treatment recommendations, many veterinarians want to know where the feedyard is at with microbial populations. With polymerase chain reaction (PCR) tests and the ability to look more closely at what type of pathogens we’re dealing with, how much testing is being done? Nels Lindberg, DVM, Production Animal Consultation, Great Bend, Kan., does some. “The struggle is cost and is it worth it for the owner of the cattle or the feed yard to do it? And what is your goal with what you’re doing? We struggle with that question and have looked at it very hard, and are still looking at it.”

Lindberg does some cultures and sensitivities on live and dead animals to see where a yard is at if there are illness breaks. “We’ve got certain yards set up with the swabs and viral and bacterial transport media, and we train them to pull the swabs, box it and get it to Kansas State University.” Lindberg notes that sometimes protocols are changed based on culture and sensitivity, if he’s received results back soon enough.

Dan Goehl, DVM, Canton Veterinary Clinic, LLC, Canton, Mo., does little testing, for the same reasons as Lindberg. “Is it economical, and will it change our treatment decision? If it’s not going to change what we do or how we react, then we usually don’t. But we do occasionally do some to look into a wreck or a major problem.”

Cattle Health Management Network’s Nate McDonald, DVM, of Meade, Kan., has taken it a step further by going back to a sourced customer and taking pre-shipment swabs. “We do a lot of buffy coat analysis for BVD. When we have a high morbidity out of a pen, we’ll examine the buffy coat from blood samples and take deep nasal swabs from affected animals and look for an array of pathogens including virus, bacteria, and Mycoplasma. We need to know what pathogens are affecting the cattle before we can develop good prevention strategies whether that is at the point of origin or at the feedyard.” McDonald usually starts with culture and PCR tests, then pathogen isolation and typing.

One of the biggest problems with testing cattle is the lag time. These veterinarians say real-time tests would make a difference in the decisions that need to be made in a timely manner. “The populations are so dynamic, how do you extrapolate that, or can you?” Portillo asks. “What you collect today in this animal, is that relative to what you’re pulling tomorrow or the day after in that pen? It goes back to what we can measure on that animal right then.”

McDonald adds if you can get a relationship with a diagnostic lab where you can get a 48-hour turn around, you can still affect the outcome of a pen of cattle. “You may not be able to be there to collect the samples, but if you train your feedyard staff to do that, you can still have a good outcome. So, I think it’s still a very valuable tool with what we have today.” McDonald says that he changes treatment protocols based on diagnostic results that support a different therapy.

Necropsies might be more valuable than live animal diagnostic in some situations. “I think necropsies are critical and we don’t do enough of them,” Portillo says. “I think there’s a percentage of our death loss that’s routinely misdiagnosed because necropsies are not performed. I do very few cultures, sensitivities because what does it change when we do? I think it makes great fodder for discussion for the academicians, and vaccine manufacturers, but on the ground floor, I don’t think it changes much what we do.” Portillo will do some PCRs if he needs to substantiate findings on gross necropsy or to look at an issue retrospectively. Lindberg says showing producers the inside of the animal can prove to him maybe he bought the problem, and it didn’t just occur. “If they’ll go to the dead pile with you and see that set of lungs, that’s probably more powerful than anything,” he says.

First treatment selection

Veterinarians examine different factors in first-treatment drug selection for BRD. McDonald analyzes hospital records in conjunction with culture and sensitivity data as early indicators of developing resistance patterns and treatment success.

For Goehl’s smaller clients, he tries to go back and analyze records and look retrospectively. “But some producers will have a bias toward one antibiotic or another, and I think we have a certain group of antibiotics that I feel better with as treatment, and a certain group of antibiotics that I feel better using as metaphylaxis,” he says. He adds that all of his yards probably use the same two or three antibiotics as their first choices.

“It’s the same with our retreatment antibiotic,” Goehl notes, “but I usually allow my producers to choose from a couple and use their preference.” The problem is when the client comes back and says antibiotic A didn’t work so he’s stopped and now is using antibiotic B. “I’ve never bought into that theory a lot,” he says. “I would guess that if antibiotic A quit, antibiotic B probably wasn’t going to work either. But I don’t usually argue with them on that point because I usually think they’re fairly equal choices.”

Al VanEngen, DVM, Central Vet Clinic, Sioux Center, Iowa, has had the same experience. “If you have a producer, feedlot manager or a cowboy who says this drug has never worked, it never will work,” he says. “We’re not going to use that one. But if you’re thinking in the back of your mind that we want to use a brand name, then use one he likes – don’t use one he doesn’t think will work. It’s half the battle because he wants to be successful as a cowboy. You start out one foot behind if you dig your boots in and say nope, you have to use that one based on sensitivity. If he doesn’t hay the cattle, bed the cattle, walk the cattle, do everything he needs to do because he wants a specific drug to fail to prove that you’re wrong, you’re going to lose.”

At his feedyards VanEngen likes to use an antibiotic for a while so he can get some numbers behind it and evaluate it. “You can’t do 10 head, say it’s not working and then switch to something else. We need to get a fair number treated, so you can actually see what was the treatment response, what was the case fatality rate, those types of things.”

These veterinarians also prepare their clients for how cattle will typically respond depending on which products they use. Lindberg says it depends on the yard and the size of the yard. “At most of my decent-sized yards the doctors and head cowboys kind of already know what to expect out of different antibiotics the next day, or within three days. You sure want to walk them through what to expect, especially in a smaller situation where the owner or the manager is doing the doctoring. Their biases can fail a product pretty easily.”

Portillo says it can be about drawing a line in the sand, even if sometimes it can be somewhat arbitrary. “The more areas of grey there are, the more you’re going to fail. So whether you want to or not, whether it’s what you deem fever is or how many days your PTI is, the more black and white that you can establish, the more successful you’re going to be because you get more consistency.” He says sometimes that means going to toe-to-toe with some of those who don’t believe in what you’re currently doing. “If you have several options and they’re all equal, and maybe the only difference is price, I get it. But if our group believes that there’s a production advantage to using one product in one setting over another, I think that’s when you’ve got to dig your heels in and say no, this is what we’ve got to use and why, and it’s our responsibility to try to educate and motivate those people as to why this is what we have to use.”

Retreatment decisions and evaluation

After first treatment, Goehl looks at about a 25% retreatment rate as standard. “There’s such a high level of variability within pens, you have to know it’s a rough rolling average.” He says it’s a lot lower in certain types of cattle such as farmer/feeder cattle or from those weaning their own home-raised cattle.

McDonald’s retreatment rate varies with the type of hospital management system that’s available. “If I get recovery pens, and an extensive recovery system, I might have a 3-5% retreat rate. If I go back to the home pen right away with single-dose therapy, then I’m right with the rest at probably 18-25%.”

Lindberg looks at both treatment success and case fatality rate. “I have my biases of where they probably should be based on a drug, and I have variations between yards. I can have one yard with a 20% case fatality rate and I find it acceptable. If they’re sitting at a .5% death loss, and I have a 20% case fatality rate, I’m all right with that. I kind of know where it should be, but every situation is different.”

Case fatality rate alone doesn’t show the whole picture. “If you just focus on case fatality rate and your cowboys know it, it’s really easy to be a good cowboy because you pull them all,” McDonald says. “Then you have a really low case fatality rate. You have to look at treatment success, number of pulls, case fatality rate and other criteria.”

Portillo believes that also goes back to case definition. “If you have a low case fatality rate and everything’s getting antibiotics, you know what’s happening. But, if you get a certain percentage of those animals that don’t get antibiotics, maybe 10-20% overall, and you have a good case fatality rate, then, you have a little bit more confidence that it might be more of the case fatality rate on the BRD cases rather than those that weren’t BRD.”

Portillo says evaluating retreatment can be tough. “I think there’s too much noise. That’s why we’ve got to rely more on well-designed controlled trials.”

Lindberg agrees. “I can show you the data on second treat success and case fatality rates. There is definitely a ton of noise. But in the last two fall runs, we’ve seen some fairly high failure rates. Whether that’s a failure rate behind the mass treatment, or a failure rate behind mass treatment and your first-line treatment has pushed us a little bit to look at some of those second-time treatments. But it’s hard to really put a value on it or put a lot of faith in that number.”

Fifteen years ago, Van Engen didn’t have any lots over 5,000 head. “I had a lot of farmer/feeders feeding 100 head,” he says. “They’d get one group in and would call you out to treat one or two. Most of them didn’t even have a bottle of antibiotics there, they just called you. Now, you get called in after an antibiotic has been used. Everything’s changed in my practice. And instead of bringing in one load of single-source cattle, now we have extensive commingling. The dynamics of farming and production medicine have changed.”

Getting a weight at and post-treatment is probably one of the most useful parameters to determine whether or not we have treatment success of failure, Portillo says. “In some instances I think it can be as useful as temperature. Weight loss or weight gain, that’s huge. We capture that weight and send them back to the home pen. It all starts with the clinical evaluation, and whoever is responsible for evaluating those cattle deems that that animal is not responding and he brings it back. If the animal is gaining weight, we may be not as apt to use an antibiotic if they don’t have a fever and they’re gaining weight. If that animal is losing weight and/or if it’s severely depressed, we are more apt to retreat it because the animal probably has not responded.”

Unfortunately, says McDonald, the veterinarian often does not see that depressed animal himself, but instead just sees records. “If you have that opportunity to see that animal, then absolutely, you can make that judgment call to retreat.”

McDonald also uses weight as an indicator of treatment success. “It can, however, be misleading if we do not zero out the scales between animals. Animals that increase in weight during treatment usually are not repulled for a second treatment.”

Moratoriums and withdrawal

Veterinarians have differing opinions on moratoriums after an animal has been treated. McDonald says if there are cattle that are obviously sick after treatment, they are pulled, especially lightweight calves. “We don’t put on a mandatory moratorium, saying that you have to shut the gate and not go in the pen,” he explains. “Some of the compounds that we use for metaphylactic treatment are not as effective on certain pathogens as others. So if the cattle are sick, we pull them. I do put a condition that if they’re going to pull three head out of a pen, they call me, and then we would walk through certain strategies and develop a plan for what we’re going to do in that pen.”

For Lindberg, using moratoriums depends on the drug, and he says it seems like the moratoriums have gotten shorter for some drugs than he initially used. “On the flipside, can you use a non-antibiotic therapy on cattle in that day three or four time period?” Lindberg asks. “It depends on the yard and how aggressive the crew is, too. We have some crews that we know pull extremely aggressively, and we know we can probably get by with some non-antibiotic therapies in that day-three to day-four timeframe. Other yards that don’t pull as aggressively, and if they’re calling me, or they’re pulling day four, they’re probably real sick.”

Portillo likes to establish post-treatment intervals. The goal is to “mark the cattle so that the cowboys and doctors know to leave them set because more so than the days you wait, I think it’s more important what happens to the cattle after you treat them. If they’re going back to an overcrowded pen, or to an overcrowded hospital, maybe it doesn’t matter what antibiotic you use.”

Obviously you have to pull cattle from a welfare standpoint, Portillo adds. “It’s not like you’re not going to touch them. If you have some clinical score threes and fours, you have to get them, it’s a welfare issue. You’re not putting a chain around the gate. I still think there’s value in getting those cattle up, pushing them toward the bunk, and doing those sorts of things as well.” You need to determine whether or not it’s an exception or the rule as it relates to switching lead-off antibiotic treatments. “If it’s an exception or a variation, then you might stay the course. If, in your impression, it’s more of a trend, then you might think it’s time to switch gears.”

Resistance and residue concerns means following withdrawal protocols to the letter. When figuring out withdrawals post-treatment, McDonald uses the longest withdrawal of any product that may have been used (by itself or used concurrently with another drug), and then adds one more day onto that to account for any influence that time of day may have had. “If it’s a 28-day withdrawal I’ll put 29 on it because most of the animals ship from the yards in the early morning and most often first day pulls are treated either just before lunch or shortly thereafter.”

Feed transitions and health

Can aggressive feed transitions undermine the health of feedlot cattle? Portillo says a big challenge from a health standpoint is trying to balance performance with health. “Not only are they pushed too hard, but maybe they are transitioned too quick,” Portillo says. “Nothing is worse than when a feedyard tries to transition a set of cattle right in the middle of a morbidity spike. I think if the nutritionists gave us the first 30 days – just those 30 days – we can get them on the right track.”

He does believe the industry is seeing some changes to this effect. “We’re seeing some differences, like being a lot more aggressive with roughage early on, and being very constant with the way that we feed the cattle. I think we’ve seen some significant improvements in health.”

On McDonald’s yards, the calf type dictates how they transition. “We spend a lot of time training our feedlot staff. If they’re a high-risk set of cattle, we don’t move or transition them through the rations until they’re ready and their health is stable. We get to help make that call for the first 30 days on this type of pen.

VanEngen says the biggest change his clients have made in the last couple of years is drying rations up. “We used to think we could start them on co-products and most of these calves had never seen any co-product. They love it, and they’ll eat it for two or three days, and then you go into the pen and you wonder if you’ve screwed up their stomach, or you don’t know if they are sick. We are drying up the ration, using more quality hay, and even with the price of corn, using more of the older-style of rations.”

VanEngen says sulfur can be an issue with the co-products and the level of sulfur in the water. “We have to keep roughage levels higher than what would be considered normal. And we do lose calves because of sulfur.”

For Goehl’s clients, more wet gluten than distillers is fed. “We’re dealing with a different type and class of cattle. We’re just growing them, getting them started, and there’s not a lot of ration changes. It’s a roughage, co-product based diet.” His clients start cattle on long-stem grass hay in the bunk, and put some ration on top to help them find the bunk. “For us it’s not a problem of overeating, it’s problem of them even finding the bunk.”

Lindberg adds that one nutritionist said that nutritionally you could not cause respiratory disease or a fever. “I said it may not directly cause respiratory disease, but through some inflammatory factors reaching pulmonary tissue, we can then have some issues,” Lindberg says. “It seems like since we’ve fed more distillers, it’s more of an acidotic, irritational type bloody discharge. We’ve done tons of sampling behind those cattle and rarely find coccidia.” Increasing the roughage in the bunk seems to pick these cattle back up.

A good relationship with the nutritionist is key. “You find out that you have a lot more common ground,” Portillo notes. “I don’t think it’s quite as an adversarial relationship as it used to be because we all have a common goal. It’s extremely important for us to understand the nutritional impacts and needs of those cattle in the first 30 days.”

“We need to do the best job we can with our therapeutic regimen. If we do not factor in all the criteria as we evaluate an animal we may not administer the correct regimen,” McDonald says. “If we administer an improper therapeutic regimen we reduce our chances for a successful recovery. The most expensive therapy we give is the one that does not recover the animal from its condition.”

This information is from a Bovine Veterinarian roundtable sponsored by Merial and moderated by Jessica Laurin, DVM.