It is seeking public input on its bid to establish appropriately targeted durations of therapeutic use of certain medically important drugs in livestock.
The comment period for the process was originally set to end in mid-December and has been extended to 13 March 2017, said the US agency.
The FDA has already set about a process enabling the voluntary ending of the use of medically important drugs in feed and water for growth promotion, along with veterinary oversight for therapeutic use and limited duration in terms of the time allowed to use some drugs.
Specific antimicrobials that are also medically important for humans and that do not currently have set timelines for usage as a treatment or preventative for certain diseases in production animals are being reviewed, said the FDA.
The agency is looking for comments from swine, poultry and cattle producers and veterinarians on when animals are most at risk for developing certain diseases; what husbandry practices might limit the need for an antimicrobial to be fed or for how long it would need to be used and thoughts on ways to address labeling.
It also is asking typically what the duration of use is of such drugs, how that duration was established, what possible benefits or problems could come from defining a use period and what other alternatives might be available instead of the antimicrobial.
Poultry, cattle and swine drugs
In poultry, the antimicrobials being discussed include ormetroprim with sulfadimethoxine; lincomycin; virginiamycin; oxytetracycline and hygromycin B, which can be used to address challenges such as chronic respiratory disease, necrotic enteritis, fowl cholera, coccidiosis, infectious coryza and gastrointestinal parasites.
Cattle products being reviewed include chlortetracycline, oxytetracycline, tylosin, virginiamycin and neomycin with oxytetracycline, the agency said. They are used to control anaplasmosis, bacterial enteritis, liver abscesses and pneumonia.
Swine producers face the possibility of restricted time period uses for tylsin; tylosin with sulfamethazine; chlortetracycline; sulfamethazine; oxytetracycline; hygromycin B; lincomycin; chlortetracycline with sulfamethazine; chlortetracycline, when given to address atrophic rhinitis, pneumonia, GI-parasites or bacteria or jowl abscesses, the agency said.