Once feedlot cattle have gone through arrival and are into the early feeding period, bovine respiratory disease (BRD) starts to make an appearance. Sickness identification, drug selection and drug use need to be carefully considered for the best therapeutic outcome.
Establishing case definitions for different conditions on each feedlot is important in order to establish protocols. “With our current technologies, most case definitions for BRD are based around an ‘undifferentiated fever’ or ‘fever and clinical score’,” says Nels Lindberg, DVM, Production Animal Consultation, Great Bend, Kan. “We have been using the same case definition for BRD for the last 100 years, with minimal advancement.”
However, with the use of pulmonary lung scoring, clinical severity scoring and rectal temperature, veterinarians have been able to more accurately assess an individual animal for BRD, and the severity of the disease, which then improves the case definition of BRD.
“An animal can run a fever for many reasons, not just BRD, and can have a high clinical score for more clinical diseases other than BRD,” Lindberg continues. “But, in association with a lung score, we begin to be more accurate with our case definition, our diagnosis, giving us more prudent and justified use of an antibiotic, which is extremely important.”
Tom Portillo, DVM, Progressive Veterinary Services, LLC, Amarillo, Texas, agrees. “You’ve got to have some way to make a case definition, or else we’re back to just treating everything with antibiotics,” he says. “I think your case definition is huge. It’s part of where we’re moving, as far as our judicious use of antibiotics. We’ve got to justify our use by showing that we’re actually making efforts to define which ones are BRD cases and which ones aren’t, instead of just treating everything.”
The pull is probably the most critical determinant for the outcome of a BRD case. Too soon and unneeded treatment costs, stress and even an interruption in normal feeding activity can place, too late and treatment costs plus an animal that is chronic or dies is often the result.
Feedlot veterinarians use a variety of scoring systems to help pen riders and the doctoring crew assess BRD animals prior to treatment. Portillo believes that the more tools he can give his feedlot employees, the better off they are. “We are working toward having employees assign a clinical score in the home pen when they first see those animals because a lot of times, their appearance is a different story once they get to the hospital. If they have that clinical score, the pen rider’s impression, we can use that as a tool chuteside. Doctors can use the pen riders’ clinical score chute side along with other criteria to help with management and treatment decisions.”
For Portillo’s depression scores in the pens, the pen riders use a range from 1-4 (mild, moderate, marked and severe). A score of 1 is for cattle just showing a change in behavior, meaning the pen rider is not sure if it’s sick, but there is something wrong, and a score of 4 would be an animal that’s moribund. Portillo says it’s important to keep it simple and quick, or it won’t get done. “We need to have pen riders take more ownership in the overall process,” he says. “The goal is to provide a snapshot of home pen appearance.”
Nate McDonald, DVM, Cattle Health Management Network, Meade, Kan., uses a 1-5 depression scoring system with 1 being mildly depressed and 5 severely depressed, and says it’s an important communication tool between pen riders and the doctoring crew.
Lindberg uses a clinical depression scoring, lung scoring and temperature in combination. For lung scoring in the hospital, he uses a 1-5 scoring system with 1 = normal, 2 = mild, 3 = moderate, 4 = severe and 5 = a chronic or AIP animal. He says using a lung scoring system can help you make better efficacious and economical drug selections.
Dan Goehl, DVM, Canton Veterinary Clinic, LLC, Canton, Mo., usually uses a 1-4 clinical illness score, and also tries to use temperature to some extent. “We use temperature as a monitoring tool to get an idea on how hard a pen may be breaking,” he says. “If every calf we pull is 108°F, that is different than if every calf is 101°F. Ambient temperature can have such an influence on rectal temperatures, though they are a long way from absolute in my mind. I feel like if you have a clinical illness score of 3 or above, then that trumps temperature. If we pick out an animal that is apparently that ill, he will still get treated regardless of his temperature because he very well may be starting to approach the temperature of dirt if we don’t.”
Timing of pen riding and scoring is crucial. In the summer, McDonald tries to have pen riders get through the pens before it gets too hot. “Ideally I train the pen rider to do the scoring in the pen while the animal is at rest or as close to the time the animal has been identified as being sick,” he says. “I think the animal is giving the pen rider the best picture of its health status at this time. This helps avoid discrepancies in scoring and keeps the system consistent.”
Scoring has to be done consistently between employees and also needs to take into account current conditions. For example, is an animal breathing heavy due to BRD, or because he just got chased around the pen in 100°F weather? “Environmental conditions need to be considered accordingly, namely when temperatures become hotter or more hot than current cattle acclimation,” Lindberg says.
McDonald agrees. “This is why this communication tool is so important,” McDonald says. “It helps prevent misdiagnosis and or mistreatment of an animal.”
Stethoscopes and thermometers
Thinking in line with veterinarians Tom Noffsinger, DVM and Wade Taylor, DVM, Lindberg encourages aggressive stethoscope use in addition to clinical scoring. “You can kind of tie those two together, but not all clinical scores will align with a lung score,” he says. “And that still goes back to your case definition.”
Not all of Lindberg’s feedlots use a stethoscope, but he has a handful that are very efficient with its use. Training the treatment crew to appropriately use a stethoscope isn’t just a matter of time, Lindberg notes. “It’s number of animals. It takes quite a few, and it takes a number of visits for me to be there with them.” When training, Lindberg lets the employee make the call first, then he gives a listen. It’s not always 100% accurate, but it works pretty well. “I was at a yard where I’ve got probably my best doctor, but we were off a little bit on our scores. Every yard will be a little bit different”
Lindberg says originally they started with lung scores of 1-10, but went to 1-5 to make it easier and compatible with technologies. “I like the one to 10,” he says. “Of course, as a scientist, probably the more options we have, there the better. When I switched to 1-5, I would think an animal was maybe a 3.5, so that’s been a little challenging, but you just need to adapt.”
Lindberg adds that it’s very important to train one or two people at a given feedlot the appropriate way to listen to pulmonary sounds, and score lungs with them. “We evaluate and check for compliance on virtually all visits,” he says. “You want consistent lung scoring. Each set of ears may hear things slightly different, but as long as a care giver has consistent scores, we can then adjust around how they score. Every yard is going to be a little different. One yard may call a few more 2s. The next one may call a few more 3s. This one may call mostly 3s, but they kind of slide some into the 4s that really aren’t 4s. That’s why you’ve got to listen with them, so you kind of know where they’re at, and make sure that they’re at least consistent.”
Cattle are great at hiding sickness, and a seemingly normal looking calf can be holding on to a high temperature – and vice versa. But temperature is still another measure in the whole picture of illness.
“If we look many of the antibiotics product that were cleared, they used a model where 104°F and above was febrile, so that’s what I use to help determine treatment,” Portillo says. “Are there animals that have an infectious process going, that are temping less than 104°F? Sure. Are there ones that have a temperature over 104°F, and not fighting infection? You bet. It goes back to drawing that line in the sand for your people. It’s our job to take as much of that grey and put it into black and white as possible, even if some of those might seem a little bit arbitrary at times.”
Lindberg has found by looking through lung score and temperature data together that in mild and moderates, temperature is a fairly accurate predictor, “And you could probably doctor quite a few cattle, based on temperature, if their lung score is a mild or moderate. But for those upper-moderates and upper-severes, you can throw your temperature out the window.”
Portillo says it’s because they stop generating fever. “The temperature goes up, and if the disease progresses, that temperature will go down. But there is no guesswork with those cattle because physically/clinically you can easily identify them.”
If you were to use only one of these scoring tools, Lindberg believes listening to the lungs may be the most accurate assessment of lung disease or BRD. “Temperature alone can be an accurate predictor in most animals, but there is a certain segment where it is not,” he says. “The more tools in the toolbox we can have, the better or more accurate we will be with individual animal evaluation and diagnosis. For all the advancements we have made in our industry over the last 100 years, we have failed miserably in individual animal BRD diagnosis.”
Training in all aspects of animal health – including sick cattle assessment -- at the employee level is one of McDonald’s most important jobs. “The more consistent a pen rider can be in scoring an animal the more consistent we can be with the proper therapeutic regimen. The first measure of compliance or pen rider accuracy happens at the chute. We begin evaluating the animal by taking the temperature, recording animal weight, checking heart rate and lung score and factor in the pen rider score to determine which treatment regimen best fits the animal’s condition.”
Using pull cards
McDonald likes to use pull cards in his yard for the pen rider to record as much information as he can about the animal’s appearance and condition in the pen. He says the most important information is the animal ID (lot number), pen ID, depression score, diagnosis (respiratory, buller, stray, footrot, calver etc.) and a severity score of mild, moderate or severe.
“What I use looks like a pocket spiral notepad with the appropriate information that is torn out and left with the hospital doctor,” he says. “We can document how we are evaluating the animal that was pulled. The worst thing that we can do is have a calf run through the chute, get treated as a respiratory, and he walks out with a limp because it was pulled as footrot and not a case of pneumonia, so pull cards are really important, and I require some type of them. In those yards where we have hospital doctors, it’s a lot easier to teach somebody to use a stethoscope. And because we post everything, if the hospital doctors are posting those, it’s a lot easier to train them. You listen to the calf here when he was alive, now look at him when it’s deceased.”
Al VanEngen, DVM, Central Vet Clinic, Sioux Center, Iowa, also uses pull cards. “Especially if you’ve got the doctoring cowboy, the first step that we tried to implement is that he needs to know what he’s treating,” he explains. “If he’s treating a lame, if he’s treating a respiratory, somebody has to make a case definition, make a diagnosis.”
VanEngen says not to worry about being wrong, but at least make that diagnosis and whether you are going to treat with antibiotics or time. “Whatever it is, make a diagnosis, and then go to what we have as our formulary or treatment protocol for BRD, a lame or a digestive, and treat accordingly. Then use your post-mortems or reevaluate your sick pen.”
“In some yards the pen riders are the doctors,” McDonald explains. “It is still an important communication tool because often if we do not have pull cards I find the cowboy that made the pull may not quite remember just why he pulled the animal.”
McDonald says even just a note pad with the correct information jotted down is sufficient to be a good communication tool. “I just think if the information is already on a card in a checkbox fashion it is more convenient for them.”
With today’s technologically advanced therapeutics for BRD treatment, giving them in a haphazard fashion just doesn’t happen. “We need to be doing the best job we can with our therapeutic regimen,” McDonald says. “If we do not factor in all the criteria as we evaluate an animal, we may not administer the correct drug regimen.”
This information is from a Bovine Veterinarian roundtable sponsored by Merial and moderated by Jessica Laurin, DVM.
Assessing pull compliance
One way to assess how well a feedlot pen rider is pulling cattle is that the more cattle pulled, the higher case fatality rate and treatment costs should be. “You have to go back through and look at the pen rider’s
pulls, and see what the results are on clinical scores 1, 2, 3, 4,” notes Tom Portillo, DVM. “Obviously, you should have an increasing case fatality rate to know that those guys are actually giving you an honest effort. And you’d be surprised from pen rider to pen rider how those will change.”
Portillo’s partner has been tracking it these rates, graphing them and, showing pen riders. “There are pen riders who are giving us an honest effort, and some just throwing a number out there to throw a number,” he says. “When you’ve got a higher case mortality rate on your 1s and 2s than you do your 3s and 4s, you know somebody’s not really giving you an honest effort.”
Size of the yard can affect compliance of scoring and pulling. Dan Goehl, DVM, says it’s generally easier to get information and data out of his larger operators. “The farmer-feeders, or the guys who are doing it as kind of a second occupation, are just not as committed and usually not as systematic about it.”
Nels Lindberg, DVM, says addressing these issues with compliance depends on the crew, your relationship with them and whether or not you’re comfortable enough to address it with them. At one of his yards he had a cowboy who was pulling too many lung score 4s. “I addressed it with him and stressed that the goal is to get better, not to point fingers and fire him. They’ll generally respond. If they don’t respond, they probably don’t want to be there anyway and they quit or the situation works itself out.”