The pros and cons of antimicrobial use in animal husbandry

There are major advantages for animal welfare and the economics of food animal production in the use of antimicrobials under veterinary prescription in the therapy and control of animal disease. Similar advantages in welfare result from their use in companion animal medicine. Antimicrobial growth promoters used in food animals also have welfare and economic advantages, killing or inhibiting harmful elements of the normal gut flora, and allowing the gut of young growing animals to function correctly. Growth rates approach but cannot exceed the genetic potential of the animal and are an indicator of health. The clear advantages for the animal and producer are accompanied by the development of bacterial resistance to almost all antimicrobials used. Bacterial antimicrobial resistance may reduce the efficacy of therapy in animals and resistant pathogens such as salmonellae and campylobacters may infect man, causing disease which may be difficult to treat. Resistant normal animal flora may also reach man on meat or by contact and colonise the human gut for varying lengths of time. The extent to which this flora transmits antimicrobial resistance to human flora or contributes to disease is not clear. Antimicrobial residues in food are uncommon and allergy to them is rare.