Starting Dec. 1, 2018, all livestock producers will need a prescription from a licensed veterinarian, before they can buy a medically important antibiotic (MIA) for therapeutic use in livestock production. This applies to all beef cattle sectors using antibiotics — cow-calf operators, feedlots and feedmills (and really all sectors of animal agriculture including beef, dairy, hogs, sheep, horses, fish and even bees).
http://www.beefresearch.ca/blog/prescription-required-for-livestock-cattle-antibiotics-december-2018/