The Anatomical Therapeutic Chemical Classification System for veterinary medicinal products (ATCvet) is used to classify veterinary drugs. ATCvet codes can be created by placing the letter Q in front of the ATC code of most human medications. For example, furosemide for veterinary use has the code QC03CA01.
Some codes are used exclusively for veterinary drugs, such as QI Immunologicals, QJ51 Antibacterials for intramammary use or QN05AX90 amperozide.
The ATC system also includes defined daily doses (DDDs) for many drugs. This is a measurement of drug consumption based on the usual daily dose for a given drug. According to the definition, "[t]he DDD is the assumed average maintenance dose per day for a drug used for its main indication in adults."
ATC follows guidelines  in creating new codes for newly approved drugs. In order to create a new ATC code, an application has to be sent to ATC. New ATC codes are published twice annually. A formal release of new ATC edition occurs once a year.