Beef cattle veterinarians and their producer clients have many choices when selecting an antimicrobial to control and treat bovine respiratory disease (BRD). The first 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 behind them to demonstrate duration and efficacy,” 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 the product performed well?

·         Allocation irregularities. Fair allocation of product is the most important aspect of an efficacy 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 flag.

·         Inconsistent results. Statistics are used to support a predetermined conclusion, rather than objectively drawing a conclusion from the data. Look for inconsistent 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 benefit, 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 were done by universities or professional contract research firms, and many of the results and conclusions have been published in refereed journals, so we have confidence in the results,” Dr. Pollreisz said.

“The biggest mistake I see is that a feedlot operation will give all the cattle in one load one antimicrobial 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 six-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 field 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 understand 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

IMPORTANT SAFETY INFORMATION: DRAXXIN has a pre-slaughter withdrawal time of 18 days. Do not use in female dairy cattle 20 months of age or older. Do not use in animals known to be hypersensitive to the product. See full Prescribing Information at