Antibiotic use in food animals has been a controversial topic for several years in the general media and medical journals. Many of these articles are written with poor information, at the very best, or information intended to mislead, at the very worst.

In addition, activist organizations constantly scrutinize our livestock-rearing practices. For these reasons, it's extremely important for producers to evaluate their use of antibiotics in food animals and ensure they're used in the most efficient and responsible manner.

Recent years have seen the introduction of new antibiotics aimed at combating bovine respiratory disease (BRD) complex. While coming from different classes pharmacologically, these newer antibiotics have a fairly constant theme — longer duration of therapy (as much as 7-14 days).

These newer antibiotics also tend to have a higher price tag. It's clear a new thought process is needed to get the best return on antibiotic investment while still providing for economically sound and humane management of our cattle.

Post treatment interval

Research on some of these new, longer-acting antibiotics has introduced the phrase “post-treatment interval” (PTI), also called “treatment moratorium” by some. This is a set period of time after treatment before the animal is allowed to be treated again. There's an increasing amount of research that supports PTI.

The PTI concept has raised some eyebrows, both positive and negative.

  • Many cow-calf and grazing operations appreciate that they can catch a sick animal on pasture and enjoy a more extended period of therapy without having to catch that speedy little bugger again.

  • Meanwhile, in the feedyard, where it's relatively easy to re-treat a sick animal, PTI is sometimes considered skeptically.

“You mean to tell me, Doc, that if I don't like the way that calf looks two days after I treat him, I still need to leave him alone?” is a common response.

Treatment savings

Company research and several studies indicate substantial savings in treatment costs are possible with appropriate use of a PTI, without increasing (and possibly decreasing) death loss.

Much of the focus has been on PTI as related to individual-animal therapy, but many of these longer-acting antibiotics are also labeled for control of BRD in cattle at high risk of developing this disease. In this scenario, all the animals in the group may have $10-$15/head in medicine costs against them before actually being pulled and treated. When this type of expense is incurred, it simply makes sense to get the most out of the antibiotic dollar.

This means knowing exactly when to initiate individual-animal treatments following administration of the antimicrobial for control. It's critical that you and your veterinarian work together to determine this time interval.

There's no free lunch. Many feel they're doing their best for a calf by rolling to a new antibiotic every 2-3 days if the response isn't as they hoped. However, there's a cost to this type of therapy.

By switching to another treatment too quickly, we shorten the total duration of therapy for the animal if you're only going to treat a certain number of times. You could be dealing with animals that need more time rather than another drug.

PTI is an attempt to balance the need for more recovery time with the need for another antibiotic treatment. It also balances the need for antibiotic therapy of sick cattle with the need to restrict application of these drugs only to cattle that truly need them.

The key to making PTI work is good management, which doesn't come in a bottle. Good feed, clean water, proper handling and a comfortable place to rest will do more for animal health than all the vaccines or antibiotics can ever do.

Another management challenge is identifying cattle for re-evaluation at the end of the PTI. Work with your veterinarian to formulate a plan to not let cattle in need of more therapy slip through the cracks.

When a calf does get sick, it must be treated as early as possible. When bacteria colonize the lung, they can go through a rapid growth phase, known as the “log phase” or “logarithmic phase,” when a few thousand bacteria can become a few billion! For this reason, it's highly important to not delay. Treat them early and then observe the PTI to allow the antibiotic to work correctly.

As an industry, we must use antibiotics to their fullest potential, but avoid overuse. If treatment costs and proper antibiotic usage are concerns to your operation, talk with your herd-health veterinarian about whether a PTI is right for you.

Dave Sjeklocha is a feedlot consulting veterinarian at the Haskell County Animal Hospital in Sublette, KS. Contact him at 620/675-8180.