Livestock Management RANCHING Evaluate Antimicrobials Beyond the Label B
EEF CATTLE VETERINARIANS AND THEIR PRODUCER CLIENTS have many choices when selecting an antimicro-
bial to control and treat bovine respiratory disease (BRD). The fi rst step for many is to compare labels, see what bacterial pathogens each product treats or controls, and look for duration and withdrawal times. The next step is to look beyond the label to the data behind the products, said John Pollreisz, DVM, Zoetis managing veterinarian. “Most antimicrobials have numerous studies be-
hind them to demonstrate duration and effi cacy,” Dr. Pollreisz said. “But it is important to understand what information is reliable and which information is more questionable.” When reviewing studies, watch for:
• Limited information. Did only one or two trials report that the product performed well?
• Allocation irregularities. Fair allocation of product is the most important aspect of an effi cacy trial. A well-structured study will randomly assign which animal receives which product, and the sample sizes will be equal or similar. If the study doesn’t explain the allocation method or describe why there are unequal sample sizes, then it is a red fl ag.
• Inconsistent results. Statistics are used to support a predetermined conclusion, rather than objectively drawing a conclusion from the data. Look for in- consistent results in the trials.
• Cyclical nature of BRD. Some years are just worse than others because of environmental factors. Every product will do well in a year when BRD pressure is low due to ideal weather conditions and other variables that support a healthy environment.
• Anecdotal conclusions. When the report is based more on a feeling or perception of an achieved benefi t, look to see whether the data supports the anecdotal conclusion. Sometimes, producers want to see real results from their own operation in addition to data from other
studies. However, there are a number of issues and inconclusive results that may result from trials that are not professionally driven. Recently, Zoetis completed a summary of trials with DRAXXIN® (tulathromycin) Injectable Solution. “Each of the trials was done by universities or professional contract research fi rms, and many of the results and conclusions have been published in refereed journals, so we have confi dence in the results,” Dr. Pollreisz said. “The biggest mistake I see is that a feedlot opera-
tion will give all the cattle in one load one antimicro- bial and then give the next load a different treatment and try to compare results,” Dr. Pollreisz explained. “The problem with that scenario: The load of cattle is a larger variable than the antimicrobial given. If one load had only a 30-minute ride to the feedlot and the next load had a 6-hour ride, then it’s not apples to apples.” A gate cut for treatment isn’t truly random either,
Dr. Pollreisz said. “To truly do the best job in the fi eld for a random test of products is to administer Product A to every other animal and then administer Product B to the ones not given Product A. You have to have two syringes going and you will need to record which animals get which antimicrobial, but you are closer to random and the results will be more reliable.” Dr. Pollreisz encourages producers to work closely
with their veterinarian to establish a protocol for an on-site comparison. “The data from study trials are important as you
evaluate antimicrobials, but it is also important that the trial was fair and unbiased in how it was set up,” Dr. Pollreisz concluded. “I encourage veterinarians and producers to ask questions if they don’t under- stand how a trial was run. In the end, it helps them trust the data behind the product.” To learn more about the summary of DRAXXIN
trials or to learn about more effective BRD control options, visit
DRAXXIN.com.
60 The Cattleman May 2016
thecattlemanmagazine.com
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