 a previous article (August 25, 2010, page 551) in this series, antibiotic resistance is not an unusual event and is a consequence of exposing bacteria to antibiotics. In the end, nearly all the antibiotics that are in our medicine toolbox are important and critical for animal and human health and must be used carefully, that is, judiciously.
First, do all things preventive. Having to treat a cow or calf is expensive. It requires extraordinary efforts on the part of yourself and your employees because it is not part of the daily routines. For your calves, use effective colostrum management and feeding programs, feed for growth, and keep feeding and housing areas clean.
For your cows, routine prevention includes an effective feeding program, a well-designed close-up or transition cow program, an effective udder health program, and keeping housing areas clean.
Think before you treat
Remember that antibiotics are not the first line of treatment. There are many conditions that do not require antibiotic therapy or are not bacterial. Calf scours may be effectively treated with fluids. Cows with high body temperatures initially may be effectively treated with aspirin or other nonsteroidal drugs that might control fever. Cows lame due to laminitis do not need to be treated for an infection.
Here again, your employees are the key to making this work. Providing them with high-quality training and consistently monitoring the effectiveness of treatment protocols and their implementation will result in judicious use of antibiotics. Work with your veterinarian to develop good approaches to correctly diagnose, treat, and monitor success or failure of a treatment protocol.
When you use an antibiotic, use it only when indicated, choose a cost-effective agent which provides appropriate antimicrobial coverage for the diagnosis that is suspected, and choose the optimal dose and duration that maximize clinical therapeutic effect while minimizing both drug-related toxicity and the development of antimicrobial resistance. Many of our decisions to treat are based on a clinical sign (scours, difficulty breathing, fever, a discharge) and not on an actual diagnosis. It is important that you and your employees have worked with your veterinarian to develop good criteria for deciding to treat. The challenge is to develop sound treatment approaches so that antibiotics are targeted and appropriate.
One of the most controversial uses of antibiotics will be the blanket use (all animals in an age or production group) to treat or prevent disease. Two dairy situations are dry cow therapy and medicated calf replacer. The evidence for using blanket dry cow therapy is strongly supportive, and there is little or no evidence that its use results in the development of resistant bacteria. This is not true for the blanket use of medicated calf replacer. There are a growing number of studies that show no benefit to feeding calves antibiotics. Calves fed antibiotics have very resistant gut bacteria, there is little evidence that the antibiotics have value in preventing diarrhea, and calves that have received adequate colostrum and fed antibiotics are more likely to have diarrhea than similar calves not fed antibiotics.
When calves are dying, the instinct is to grab for that bottle of antibiotics. At the moment, that may seem to be the best decision, but over time what was a judicious decision becomes a habit and given time and circumstances may no longer be a good decision.
We all share in the responsibility to protect the value of antibiotics for treating animal and human disease. Developing judicious use guidelines that can be applied by you and your employees is an obligation that we have as partners in public health.