Swine veterinarians need to develop a philosophy concerning the use of antibiotics in pork production, says long-time Indiana veterinarian Larry Rueff.

“My philosophy has been based on science, proper use, no abuse and economic consideration,” says Rueff, a former president of the American Association of Swine Veterinarians. “Food safety for the consumer is a must as well.”

Rueff believes that the use of antibiotics in swine production has been a positive economic tool for disease prevention and control and improved performance. “In addition, food safety has been enhanced by reduction of food-borne pathogens that can result in consumer illness.”


Antibiotic use in gestation diets usually is not necessary, says Indiana swine veterinarian Larry Rueff.

How antibiotics are used
In order to develop a workable philosophy regarding the use of antibiotics in pork production, Rueff says you need to first look specifically at how certain classes of antibiotics are being used. He provides the following considerations:

  • Feed grade medications. These probably represent the largest potential for improper use. “The inclusion of an antibiotic can become a habit rather than a consideration as to its necessity. Situations change on a farm, and often products are added without regard to replacing what is already in the diet. In addition, misunderstanding or lack of education can result in improper inclusion rates and thus the wrong formulation.” Because feed-grade antibiotics represent the highest percentage of antibiotic usage and cost on a farm, Rueff says it is imperative that these products are used properly at the correct inclusion rate as well as in the right combination and sequence.
  • Injectable antibiotics. As farms have gotten larger, these types of antibiotics are being used less on a per-pig basis, according to Rueff.  The potential for misuse in this area comes more from a concern for proper animal identification when treated so that correct withdrawal times are followed.
  • Water formulations. Can be a good treatment tool for mass medicating pigs. Producers often turn to this tool because it is relatively easy, says Rueff. “Proper timing, correct dosage and not overusing must be watched. Water wastage in drinkers and nipples can result in economic waste,” he adds.

Antibiotic in a lactation diet at a low level can have benefits on improved pre‑weaning mortality and improve weaning weight.

Antibiotics role in production
In developing an antibiotic-use philosophy, the next step is to take a look at their potential role in specific parts of a pork production system, according to Rueff. “I want to look at antibiotic usage and think about it in relation to treatment, growth promotion and disease prevention. Different areas of the farm have different potential needs.” The specific areas that Rueff considers would include:

  • Acclimation. Routine use of antibiotics in feed can play a role in this area of production, says Rueff. “One of the biggest concerns often is proliferative ileitis in incoming gilts. Preventative medication at this time can have a very worthwhile impact and can prevent this disease situation from occurring. Prevention is always important because I have seen ileitis breaks that did not always respond as well to treatment.”
  • Breeding. “Antibiotics as a routine inclusion in breeding diets as a follow-up coming out of lactation have been reported to improve farrowing rate. Good scientific studies are hard to find on this topic. Most reports of improvement are anecdotal. If a female has been on a antibiotic program in lactation, I do not feel that it is necessary to include antibiotics as a prevention in the breeding stage.”
  • Gestation. “Gestation diets usually have no necessity for inclusion of antibiotics. Typically the usage of antibiotics in gestation revolves around issues with proliferative ileitis. In my experience ileitis is more of a summer issue in gestation and some preventative pulse inclusion of antibiotics for two to four weeks and repeated a month later have done clinically and economically what needed to be accomplished. “Historically, some units use broad-spectrum antibiotics to decrease discharges in sow herds. It is my experience that this does not work. The good news is that since most herds have gone to artificial insemination, discharges from sows have become almost a non-event.”
  • Lactation. “My experience has been that inclusion of an antibiotic in a lactation diet at a low level such as 100 to 200 grams can have benefits on improved pre‑weaning mortality and improve weaning weight. However, each farm should look at this individually. Some farms are able to not include a feed grade antibiotic in these diets but still have excellent farrowing house performance. “In addition, some MEW and SEW programs look at use in lactation diets to try to prevent spread of respiratory infections to the pig. These programs must be evaluated carefully as to expected results and economic feasibility because these are usually at higher inclusion rates than standard preventive levels.”

    Losing the opportunity to use antibiotics in the nursery phase of pork production could ultimately result in significantly decreased productivity from a growth rate and feed efficiency standpoint.

    Nursery. “Growth promoters and feed efficiency antibiotics have resulted in improved gains and feed conversion in this period of high stress in the pig’s life. Reductions in respiratory disease and enteric disease are often seen as well,” says Rueff. “It would appear to me that the loss of antibiotics at this stage of production over the long term could result in significantly decreased productivity from a growth rate and feed efficiency stand point. The improved health and growth of a pig due to these products is real. The impact on subsequent improved health and growth is real as well.”

  • Finisher. “Finishing decisions on antibiotic usage for growth and performance need to be looked at carefully. As we move into the late stage of finishers it appears we can get good production without having to resort to growth promotion and feed efficiency levels of those products in some situations. Early finishing phase pigs often are susceptible to ileitis and respiratory diseases. Use of feed grade antibiotics for preventing disease may have some benefit in this stage.”

Annual review
An annual review of antibiotic use also should be a part of your antibiotic-use philosophy, according to Rueff. “This should involve all products that are routinely used in the feed, typical water medications and all injectable programs.”


Decisions on antibiotic use in finishing pigs for growth and performance need to be looked at carefully, says Larry Rueff, Indiana swine veterinarian.

It also is important to train employees in the proper use and dose calculations for antibiotics so that the correct doses are being used on the farm. “New training has to occur constantly. Withdrawal times must constantly be reinforced.”

Rueff says that by developing a proper philosophy for antibiotic use and conveying it to clients, swine veterinarians will be more effective in helping to ensure that the use of
antibiotics in pork production is not an issue.

He concludes that ultimately food safety is the most important consideration. “We do not want to be creating long‑term resistance through indiscriminate use of antibiotics,” he says. “However, we also must realize that the low level inclusions (of antibiotics) for growth rate and feed efficiency have also improved food safety for humans while improving on-farm performance.

“I feel that the use of antibiotics is a must to continue the safe food programs we currently have and have enjoyed in the United States.”

Editor’s note: Information in this article was edited from a paper originally presented at this year’s American Association of Swine Veterinarians Annual Meeting in Toronto, Canada.


Food safety is one of the most important considerations in using antibiotics in pork production.