
In Ruminants
Antibiotics are powerful medicines that are used to fight bacterial infections. Early civilizations used antibiotics in some form or another (e.g. mold), but didn’t know how they worked. The earliest discovered and still most widely-used antibiotic is Penicillin.

Sir Alexander Fleming is given credit for “accidently” discovering Penicillin in 1928. He shared a Nobel Prize in 1945 with the men who developed the technology to mass produce it. Penicillin saved the lives of many Allied soldiers during the Second World War and many lives since.
For more than 40 years, antibiotics approved by the Food and Drug Administration (FDA) have been used to treat sick animals, prevent illness, and maintain the health of animals. Several layers of protection have been put into place to make sure antibiotic use in livestock does not cause harm to humans.
Therapeutic uses of antibiotics by the sheep and goat industry
Therapeutic use of a drug means that it is being used to treat (sometimes prevent) a disease. Penicillin (many brand names) is probably the most widely used antibiotic in the sheep and goat industry. It is FDA-approved to treat sheep for bacterial pneumonia caused by P. multocida. Slaughter withdrawal is 9 days. Use in goats requires veterinary approval. Long-acting penicillin is not FDA-approved for sheep or goats and requires veterinary approval.
Naxcel® (Ceftiofur Sodium) is FDA-approved to treat sheep and goats for respiratory disease (pneumonia); however, its use is restricted to veterinarians. There is no slaughter withdrawal. Micotil® (tilmicosin phophate) is another prescription drug that is FDA-approved to treat sheep for pneumonia. Slaughter withdrawal is 28 days.
Though commonly administered to sheep and goats, LA-200® (oxytetracycline), Nuflor® (Florfenicol), Excenel® (ceftiofur hydrochloride), Scour-halt® (spectinomycin), Cefa-Dri® (cephapirin benzathine), and Cefa-Lak® (cephapirin sodium) are not FDA-approved for use in any class of sheep or goats. Use of these drugs constitutes extra-label drug use.
Due to the lack of approved drugs, it is often necessary to treat sheep and especially goats with extra-label drugs.
Ub-therapeutic uses of antibiotics by the sheep and goat industry
Sub-therapeutic use of a drug is when the drug is administered at a level lower than required to treat disease. The purpose of sub-therapeutic use is to prevent disease. An added benefit has been increased performance by livestock.
Aureomycin® (tetracycline) is FDA-approved for use in growing lambs to increase rate-of-gain and improve feed efficiency. It is commonly included in lamb feed lot rations. There is no slaughter withdrawal. Auromycin® is also approved for breeding sheep to prevent the incidence of abortion caused by Campylobacter fetus infection (vibriosis).
Antibiotic use under attack
For many years, the use of antibiotics in animal agricultural has been under intense scrutiny by special interest groups. The Preservation of Antibiotics for Medical Treatment Act of 2009 sought to eliminate the “sub-therapeutic” use of antibiotic drugs in livestock .
The intent of the bill is to decrease the development of antibiotic-resistant bacteria in humans. Introduced by the late Senator Edward Kennedy, the bill had the support of the president. Advocates for the bill were hoping to include the measure in the legislation to reform health care.
In addition to seeking to ban the use of “sub-therapeutic” antibiotics, in written testimony to the House Rules Committee, Dr. Joshua Sharfstein, principal deputy commissioner of food and drugs, said “farmers should no longer be able to use antibiotics in animals without the supervision of a veterinarian.
Alternatives to antibiotics
There are potential alternatives to antibiotics. Probiotic and prebiotic are the terms given to direct-fed microbial (DFM) products. Direct-fed microbials are products that claim to contain live microorganisms such as bacteria and/or yeast that are thought to aid digestion and digestive tract health.
Enzymes are protein molecules that catalyze specific chemical reactions. Several enzymes have by studied for use as additives in animal feeds.
Different Antibiotics

Our understanding of how and when probiotics, prebiotics, and enzymes improve animal health and performance is in its infancy. Time is needed to conduct the research. Products must also proven to be safe relative to animal, humans, and the environment.
The market is currently littered with products containing DFM and enzyme additives. However, many products contain only trace amounts of the active ingredients and have little or no published data to support an improvement in animal health or importance.
FAQ’s about antibiotic use in Sheep Goats and Livestock
1. Q: What are antibiotics used for in livestock?
A: To treat, prevent, and control bacterial infections.
2. Q: Can antibiotics treat viral infections in animals?
A: No, antibiotics are only effective against bacterial infections.
3. Q: What is antibiotic resistance?
A: It’s when bacteria become resistant to antibiotics, making infections harder to treat.
4. Q: What causes antibiotic resistance in livestock?
A: Overuse, misuse, and not following proper withdrawal periods.
5. Q: What is a withdrawal period?
A: The time between the last antibiotic dose and when the animal’s products (meat/milk) can be safely consumed.
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Disclaimer: This article is for educational purposes only. Always consult a licensed veterinarian for proper diagnosis and treatment.