Which of the following NSAIDs is known for being PO and has a zero residue tolerance in cattle?

• A. Aspirin
• B. Phenylbutazone
• C. Ibuprofen
• D. Carprofen

Answer: (B)

Phenylbutazone is an NSAID commonly used in veterinary medicine, particularly for treating pain and inflammation in horses and cattle. It is administered orally (PO), making it convenient for field use. One significant aspect of phenylbutazone is its established zero residue tolerance in cattle, meaning that any detectable level of the drug in the meat or milk is unacceptable. This is critical for food safety, ensuring that consumers are not exposed to residues of this medication through their food supply.

The zero residue tolerance policy is particularly important in food animals due to the potential health risks associated with drug residues in human food. Compliance with such regulations helps maintain public trust in the safety of animal products.

In comparison to other NSAIDs listed, aspirin, ibuprofen, and carprofen do not have the same regulatory standing regarding zero residue tolerance or may not be as widely accepted for use in food animals, especially ensuring meat quality for human consumption. Therefore, phenylbutazone stands out in this context due to its specific approval and established guidelines surrounding its use in livestock.