Make sure, though, that you’re familiar with the standards and recommendations provided by the certifying bodies that you’re part of, as they do differ slightly.
Red Tractor Assurance, for example, states that HP-CIAs must only be used as a ‘last resort under veterinary direction’. They use the European Medicines Agency’s definition of HP-CIAs, which includes 3rd and 4th generation cephalosporins, fluoroquinolones and colistin. They also say that the use of these products must be supported by a vet report outlining sensitivity test or diagnostic test results.
Other certifying bodies or milk buyers also include macrolides in their HP-CIA list (e.g. Tylan and Draxxin). Some say no HP-CIAs are allowed at all, and some (like Red Tractor Assurance) say they can be used when culture and sensitivity demonstrate that they are the most appropriate option. Do read your small print, and do ask us if you need any help interpreting it!