Nuflor is a prescription antibiotic for cattle, used primarily to treat bovine respiratory disease (BRD) and foot rot. Its active ingredient, florfenicol, works by stopping bacteria from building the proteins they need to survive and multiply. It’s approved for use in beef cattle and non-lactating dairy cattle.
Bovine Respiratory Disease
BRD is the most common reason ranchers and veterinarians reach for Nuflor. The drug targets three bacteria responsible for most bacterial pneumonia in cattle: Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni. These organisms cause the fever, labored breathing, nasal discharge, and depression that cattle producers know as “shipping fever,” since it often hits stressed animals shortly after transport or arrival at a feedlot.
Nuflor doesn’t just treat active BRD infections. It’s also approved for controlling respiratory disease in cattle considered high risk for developing BRD, such as newly weaned calves or freshly received stockers. In lab studies, florfenicol doesn’t merely slow down the growth of M. haemolytica and H. somni; it actually kills those strains outright, which sets it apart from antibiotics that only inhibit bacterial growth without destroying the organisms.
Foot Rot Treatment
Nuflor’s second labeled use is bovine interdigital phlegmon, the condition most producers call foot rot. This painful infection between the toes causes sudden, severe lameness and swelling above the hoof. Two anaerobic bacteria drive the infection: Fusobacterium necrophorum and Bacteroides melaninogenicus. Both thrive in the muddy, wet conditions that break down the skin between a cow’s toes, giving bacteria an entry point. Nuflor targets both organisms, helping resolve the swelling and lameness that can pull weight off cattle and cut into gains.
How Florfenicol Works
Florfenicol belongs to the same antibiotic family as chloramphenicol but was specifically engineered for veterinary use. It binds to a specific part of the bacterial cell’s protein-building machinery (the 50S ribosomal subunit) and blocks an enzyme called peptidyl transferase. Without that enzyme, bacteria can’t assemble the proteins they need to function and reproduce. This mechanism is classified as bacteriostatic, meaning it stops bacterial growth. However, against certain BRD pathogens like M. haemolytica and H. somni, florfenicol crosses the line into bactericidal activity, directly killing those bacteria rather than simply holding them in check.
Important Use Restrictions
Nuflor carries several restrictions that cattle producers need to keep in mind. The most significant is a flat prohibition on use in animals intended for breeding. Toxicity studies in dogs, rats, and mice linked florfenicol to testicular degeneration and atrophy, and the effects on bovine reproductive performance, pregnancy, and lactation have never been formally evaluated. That means bulls you plan to use for breeding, replacement heifers you intend to keep, and pregnant cows should not receive Nuflor.
The drug is also not approved for use in lactating dairy cattle. If you’re running a dairy operation, Nuflor is limited to non-lactating animals such as dry cows or dairy-breed calves not yet in the milking string.
Storage and Handling
Nuflor Injectable Solution should be stored between 36°F and 86°F (2°C to 30°C) and never above that upper limit. Once you puncture a vial, it needs to be used within 30 days, and no single vial should be punctured more than 30 times. If you’re working through a large group of cattle, keeping track of when you opened the bottle matters for both efficacy and compliance. Using product past these limits risks reduced potency and potential injection site issues.