Florfenicol is a broad-spectrum antibiotic that exhibits good inhibitory effects against both Gram-positive and Gram-negative bacteria. Therefore, many pig farms frequently use florfenicol in large quantities to prevent or treat diseases, especially during outbreaks. Some veterinarians on these farms use excessively high doses of florfenicol indiscriminately across different diseases, age groups, and stages. However, florfenicol is not a panacea and must be used rationally to achieve the desired effects.

Florfenicol is commonly used in pig farms as an antimicrobial agent. It has a broad spectrum of activity, effectively killing Gram-positive and Gram-negative bacteria, anaerobic Gram-positive bacteria and spirochetes, Leptospira, Brucella, and other parasites. Both in vitro and in vivo studies have shown that florfenicol's antibacterial activity is significantly superior to other antibiotics currently in use, such as chloramphenicol (now banned), thiamphenicol, tiamulin, tetracyclines, and ampicillin, as well as fluoroquinolones widely used today. After intramuscular injection, florfenicol reaches therapeutic concentrations in the bloodstream within one hour, with peak concentrations achieved in 1.5 to 3 hours; a single dose maintains effective blood drug levels for over 20 hours. Additionally, florfenicol can penetrate the blood-brain barrier, making it effective in treating bacterial meningitis in animals, an effect unmatched by other antibiotics. When used at recommended doses, it is non-toxic and overcomes the risks of aplastic anemia and other toxicities associated with thiamphenicol. It is used to treat systemic infections caused by bacteria in various parts of animals, including respiratory diseases, meningitis, pleurisy, mastitis, intestinal infections, and postpartum syndrome in pigs.

1. Preferred uses of florfenicol in pigs:

It is recommended as the first-choice drug for swine fever, contagious pleuropneumonia, and Actinobacillus pleuropneumoniae infection, particularly suitable for treating bacteria resistant to fluoroquinolones and other antibiotics.

2. Florfenicol can also be used to treat the following pig diseases:

It can also be used to treat respiratory diseases caused by various streptococci (pneumonia), Bordetella bronchiseptica (atrophic rhinitis), Mycoplasma hyopneumoniae (Porcine Respiratory Disease Complex), as well as intestinal diseases such as Salmonella infection (piglet paratyphoid fever), Escherichia coli infection (piglet yellow and white scours, edema disease), and other sensitive bacteria. Florfenicol can be used to treat these pig diseases, although it is not the first-choice drug for these conditions, so its use should be cautious.

Common misconceptions in pig farms:

1. Incorrect dosage—some use feed mixing to reach doses of 400 mg/kg, with injection doses ranging from 40 to 100 mg/kg or even higher, while others use doses as low as 8 to 15 mg/kg. Excessive doses can lead to toxicity, while insufficient doses are ineffective.

2. Prolonged use—a lack of restraint in long-term high-dose medication.

3. Incorrect application to the wrong subjects or stages—improper use in pregnant sows and fattening pigs can lead to toxicity or drug residues, compromising the safety of production and food.

4. Improper drug combinations—frequent combinations of florfenicol with sulfonamides or cephalosporin drugs raise questions about scientific rationality.

5. Ineffective feed mixing—poorly mixed feed administration can result in ineffective medication or drug toxicity.

Precautions for using florfenicol:

Avoid combining it with macrolides (such as tilmicosin, erythromycin, tylosin, tilmicosin, tylosin, archromycin, and clindamycin), lincosamides (such as lincomycin and clindamycin), or semi-synthetic antibiotics like pleuromutilin when used together, as antagonistic effects may occur.

Florfenicol should not be used in combination with β-lactam antibiotics (such as penicillin or cephalosporins) or fluoroquinolones (such as enrofloxacin or ciprofloxacin) because florfenicol acts as a rapid bacteriostatic agent inhibiting bacterial protein synthesis, whereas the latter act as fast bactericidal agents during the reproductive period. Under the action of the former, bacterial protein synthesis is rapidly inhibited, stopping bacterial growth and reproduction, thereby reducing the bactericidal effect of the latter. Therefore, they should not be used together when rapid bactericidal action is needed.

Avoid mixing it with sodium sulfadimidine for injection. When administered orally or by injection, it should not be used in combination with alkaline drugs to avoid decomposition and ineffectiveness. Also, avoid mixing it for intravenous injection with tetracycline hydrochloride, kanamycin, adenosine triphosphate, coenzyme A, etc., to prevent precipitation and reduce effectiveness.

After intramuscular injection, it may cause muscle degeneration and necrosis; therefore, alternate deep intramuscular injections between the neck and hip regions are advisable, avoiding repeated injections in the same area.

Due to potential embryotoxicity, it should be used with caution in pregnant and lactating sows.

In cases of high fever in sick pigs, it may be used in conjunction with antipyretic analgesics and dexamethasone for better results.

In the treatment of Porcine Respiratory Disease Complex (PRDC), some recommend combining florfenicol with amoxicillin, florfenicol with tilmicosin, or florfenicol with tiamulin. However, this approach is inappropriate from a pharmacological perspective because these combinations are not recommended. Florfenicol, however, can be used in combination with tetracyclines such as doxycycline.

Florfenicol has hematologic toxicity, although it does not cause irreversible aplastic anemia, reversible inhibition of red blood cell production is more common than chloramphenicol (now banned). It is contraindicated in animals during the vaccination period or when there is severe immunodeficiency.

Long-term use may cause digestive dysfunction and symptoms of vitamin deficiency or secondary infection.

In the prevention and treatment of pig diseases, caution should be exercised, and it should be administered according to prescribed doses and treatment regimens to avoid misuse and adverse consequences.

For animals with renal insufficiency, the dose should be reduced or the dosing interval extended.

In case of slow dissolution due to low temperature or precipitation of prepared solutions containing florfenicol, slight warming (not exceeding 45°C) can quickly dissolve the precipitate. Prepared solutions should ideally be used within 48 hours.

Following the above instructions and using appropriate formulations and recommended doses, florfenicol use is safe. Some animals may experience temporary decreased appetite, reduced water intake, diarrhea, slight pain at the injection site, or mild tissue reaction, all of which are normal and resolve after discontinuation of the medication.