When an animal appears ill, there is a tendency to grab an antibiotic bottle. This is a bad habit for many reasons. First, antibiotics are not cure-alls. They are only effective on bacteria and have no effect on viruses, parasites and other organisms. In addition, every type of antibiotic does not control every kind of bacteria. Therefore, it is important to correctly diagnose the cause of sickness before selecting a treatment.
“Antibiotic overuse can lead to resistance, because there are a certain number of bacteria in an animal that are able to survive the treatment,” said Virginia Fajt, DVM, of the College of Veterinary Medicine at Texas A&M University. “These remaining bacteria are resistant to the applied antibiotic and may also be resistant to other products in the same chemical family. Resistant populations of bacteria on a ranch, in a region or in a country means the drug or family of drugs is no longer effective.”
Another reason to use antibiotics judiciously: Treatment without diagnosis can result in an expense that is not beneficial. In addition to wasting money on the antibiotic, reduced animal production or death may occur, further increasing the financial loss.
“Concern over antibiotic resistance has promulgated use restrictions issued by the FDA,” said Paul Ebner of Purdue Animal Sciences. “Use of antibiotics as growth promotants are no longer approved if they are deemed medically important for human medicine. There are several antibiotics used for growth performance that are not on the medically important antibiotic list. An example of nonmedically important antibiotics are ionophores such as Rumensin and Bovatec.”
“Certain antibiotics can no longer be administered in mixed feed, milk replacer or mineral blocks unless a written veterinary feed directive order has been issued by a licensed veterinarian,” said Tom Hairgrove, DVM, Texas A&M AgriLife Extension. “A vet cannot write a VFD order unless they have a veterinary-client-patient relationship with the person using the medicated feed. Currently all antibiotics used in livestock drinking water require a prescription.”
“A vast majority of injectable antibiotics now require a prescription from a licensed veterinarian,” said Kynan Sturgess, DVM, of Hereford, Texas. “There are a few products still available over the counter, including penicillin, oxytetracycline and sulfadimethoxine. It is likely Food and Drug Administration will force withdrawal of these OTC labels within the next two years. At this point, all antibiotics will only be available with a prescription.”
If the above restrictions don’t adequately address public and government concerns over antibiotic resistance, then it is possible that some product families will be removed from livestock markets. Proper use of antibiotics is not only important for stemming development of resistance, but it is also a good product stewardship and animal welfare practice.
Beef Quality Assurance guidelines
Beef Quality Assurance is a nationally coordinated, state-implemented program that has developed guidelines for best practices in beef production. The guidelines include the judicious use of antibiotic practices, listed at www.bqa.org/Media/BQA/Docs/judiciousmicrobials.pdf.
The first recommendation is to prevent problems by emphasizing appropriate husbandry and hygiene, routine health examinations and vaccinations. Consult with your veterinarian on selection and use of antibiotics. Have a valid reason to use an antibiotic. Consider therapeutic alternatives prior to using an antibiotic.
Do not use an antibiotic that is important for treating human infections unless it is absolutely necessary. Use laboratory cultures and susceptibility test results to aid in selection of antibiotics whenever possible. Combination antibiotic treatment is discouraged unless there is clear evidence the specific practice is beneficial.
Avoid inappropriate antibiotic use by confining therapeutic antibiotic treatment to proven clinical indications of the problem. Avoid inappropriate uses of antibiotics such as treating for viral infections without bacterial complication. For instance, bovine respiratory diseases are caused by one or a combination of the following microorganisms:
• Viruses: bovine respiratory syncytial virus, parainfluenza 3, bovine viral diarrhea, infectious bovine rhinotracheitis and bovine coronavirus.
• Bacteria: Pasteurella multocida, Mannheimia haemolytica, Histophilus somni and Mycoplasma bovis.
If one of the bacteria is exacerbating the virus problem, then treatment with an antibiotic is warranted.
Antibiotic treatment programs should reflect best use principles. Optimize therapeutic antibiotic systems using current pharmacological information and principles. Treat the fewest number of animals possible by limiting antibiotic use to sick or at-risk animals. Treat during the label-recommended time period to minimize potential for bacteria to become resistant to antibiotics due to reduced treatment effectiveness.
Avoid environmental contamination with antibiotics. Take steps to minimize microbial spillage, ground contamination and volatilization. Keep accurate treatment and results records to evaluate therapeutic regimens. Follow label instructions and never administer antibiotics for uses that are not labeled without a valid veterinary prescription. Always follow proper withdrawal times listed on the label. Also refer to the label for instructions on disposal of product packaging, unused antibiotics, needles and syringes.
Extra-label antibiotic use must follow FDA regulations, which are found at www.fda.gov/AnimalVeterinary/ResourcesforYou/ucm380135.htm. Extra-label is using an approved drug in a way that isn’t listed on the drug’s label. Extra-label drug use is sometimes called off-label because the use is not on the label. A valid veterinarian-client-patient relationship is the first requirement for legally applying extra-label uses. Only a licensed veterinarian can administer off-label applications.
General conditions for extra-label drug use include the following:
• There is no animal drug approved for the intended use.
• There is an animal drug approved for the intended use, but it does not contain the needed active ingredient.
• The approved drug is not available in the required dosage form. For example, a liquid dosage form is needed, but the approved drug is only available as a tablet.
• The approved drug is not available in the required concentration. For example, a 5 milligram concentration is needed, but the drug is only available in 50 milligram dosages.
• The approved drug is ineffective when used as labeled.
Conditions for extra-label drug use in food-producing animals stipulate that veterinarians carefully diagnose and evaluate the condition before prescribing the drug. The veterinarian is to ensure procedures are in place for the client (producer) to maintain identity of the treated animals. A substantially extended withdrawal period, supported by appropriate scientific information, is required. The veterinarian and client must take measures to ensure that no illegal drug residues occur in the treated animals.
The last Beef Quality Assurance guideline for judicious use of antibiotics discourages subtherapeutic uses. In addition, the guidelines limit antibiotic use to preventing or controlling disease and not for the principle intent of improving performance.