Veterinarians and farmers recognize that diseases can spread rapidly, so when one animal shows symptoms of a disease or becomes ill, the animals around it are likely to get sick and may die if they aren’t treated. This is known as preventive antibiotic treatment.

Historically, antibiotics have also been used in animals to encourage growth. But with a change adopted by the animal health community Jan. 1, 2017, antibiotics important to human medicine are used only for treatment, control and prevention of disease in animals – not growth promotion.