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OSU Extension

College of Food, Agricultural, and Environmental Sciences

June 5, 2017 - 8:13am -- Anonymous

One important aspect of responsible livestock management is to care for sick animals.  In some instances, this may require the administration of drugs to help alleviate pain, promote healing and return the animal to health.  Depending upon the illness, injury, and treatment regimen the animal may no longer fit into the production system and the livestock manager must make a decision to send the animal to slaughter.  In that case, livestock managers need to consult the drug label for information about the withholding period or withdrawal time necessary from the time drug treatment has stopped until the animal can enter the slaughter channel.  The goal is to allow time for the drugs to clear the animal’s system and to prevent drug residues in the food chain.

Recently I read an interesting article entitled “User Beware: Drugs Take Longer to Clear in Sick Animals” on the bovine veterinarian on-line web site.  The entire article is available on-line at, but I want to summarize some important points brought up in the article that livestock producers should be aware of.  The central point was healthy animals are routinely used to determine label withdrawal times.  However, drug clearance in sick and/or diseased animals can take longer than the withholding period stipulated on the drug label.  Livestock producers should consider this when animals that have been sick and treated with drugs are being culled and sent to slaughter.  Although the focus of the article was on dairy cows, the principles apply across livestock species.

            Some other good points brought up in the article include:

  • Route of administration affects drug clearance.  An example was given of a particular drug with a correct administration to the base of the ear that allowed residues in meat to clear in 13 days.  However, that same drug given as an intramuscular injection required a withdrawal time of 90 days and if administered subcutaneously, the withdrawal time was 140 days.
  • Record keeping is critical when treating sick animals with drugs.  Record the date, time, specific drug and route of administration.  Keep notes on whether the animal recovered or needed repeat treatments.
  • Euthanasia may be the better option for cattle treated extensively and repeatedly with drugs rather than allow them to enter the food stream.
  • Livestock producers should work with their veterinarians to develop antibiotic treatment protocols and withdrawal periods.
  • Employees should receive training that allows them to competently administer drugs, identify treated livestock, keep records and calculate withdrawal times.