Mike Apley, DVM, PhD, and associate professor of production medicine and clinical pharmacology for the
Apley presented some of this information during the recent Stocker Field Day hosted by
Apley’s presentation ended up being a “mythbuster” when he outlined several commonly held beliefs about antibiotic therapy strategies for stocker cattle. He helped listeners identify what treatment strategies are grounded in truth and which ones are not. Several commonly held myths and the truth of the matter when it comes to microbial therapy are outlined below.
If one is good, then two is better
Not true, according to Apley. Any hope of gaining a synergistic effect by using more than one antimicrobial therapy is outweighed by the added time, cost and injection site lesions that might occur. Additionally, the activity of some antibiotics might be impeded when given at the same time as another product.
Change is good
The expectation that cattle should respond uniformly to a therapy within a period of a few days is unrealistic, and the idea that you should change a therapy if the cattle are not responding within a certain amount of time is a bad one. Rather, Apley recommends that if you are using a reasonably effective antimicrobial and are getting a good response in most of the cattle, the cattle that aren’t showing a response may need continued therapy versus a change in therapy.
Nothing cures like a cocktail
Adding supplementary drugs such as steroids to an antibiotic regime has often been thought to improve the response; however, Apley says that no data exist to support that claim, and in fact, the strategy might be harmful to a clinical response. Additionally, many people think that adding vaccination at the time of treatment for respiratory disease can also enhance results. Apley says that there is no data to indicate that to be true either.
Johnny come lately may be your saving grace
If you switch your antibiotic five to seven days into an outbreak, then the second antibiotic will work wonders has been an oft-held belief; however, Apley says that the idea doesn’t hold water. The time from initial treatment to death will often be shorter — just a few days — and the number of treated cattle that die will often be higher in the first few days of receiving a compromised set of cattle. Since the cattle were well along in the disease process when they arrived, if you switch to a new drug within a few days, the second drug will appear to be more effective even when it may not be.
There is no magic bullet (and be wary of those who say they have one)
Apley emphasizes that successful treatment options include choosing an appropriate antibiotic for individual treatments and one for prevention and control in group situations. Develop a treatment protocol and stick to it.