Food Animal Drug Regulations
Level A. Use the withdrawal recommendation look up http://www.farad.org/wdilookup/ to find the withholding on lidocaine used for a local block in a dairy cow.
Level A. What about xylazine? Is it FDA approved? Can you find withholding information?
Obviously we often use drugs that are not FDA-approved but that does mean we have to carefully follow AMDUCA guidelines (and are not uniformly good at doing so). While we tend to consider FARAD calculated withholding times as “approved” this does not equate to FDA approved drugs and label withholding.
If the drug is approved, the label should have the recommended withholding information (or a google search for the drug label should work).
See this example for Ceftiofur in swine