Prevail is a brand-name injectable anti-inflammatory drug used in cattle primarily to control fever, reduce inflammation, and manage pain. Its active ingredient is flunixin meglumine, a nonsteroidal anti-inflammatory drug (NSAID) that works similarly to ibuprofen in humans but is formulated specifically for livestock. In cattle, Prevail is approved for three main conditions: fever from bovine respiratory disease, inflammation caused by endotoxemia, and acute mastitis.
How Prevail Works
Flunixin meglumine, the active compound in Prevail, blocks an enzyme called cyclooxygenase (COX). This enzyme is responsible for producing prostaglandins, which are chemicals the body releases in response to infection or tissue damage. Prostaglandins drive fever, swelling, and pain. By shutting down their production, Prevail lowers body temperature, reduces inflammatory swelling, and provides pain relief, often within hours of administration.
Approved Uses in Cattle
Prevail injectable solution is labeled for three specific situations in cattle:
- Bovine respiratory disease (BRD): This is one of the most common and costly illnesses in feedlot and stocker cattle. Prevail is used to bring down the high fevers that accompany BRD, making the animal more comfortable and more likely to continue eating and drinking while antibiotics address the underlying infection.
- Endotoxemia: When gram-negative bacteria die off in large numbers (sometimes triggered by severe gut illness or infection), they release toxins into the bloodstream. This can cause dangerously high fever, shock, and widespread inflammation. Prevail controls both the fever and the inflammatory response associated with this condition.
- Acute mastitis: In dairy cows, sudden udder infections cause significant pain, swelling, and fever. Prevail is used as a single-dose treatment alongside antimicrobial therapy to reduce inflammation and discomfort in the affected quarter.
Administration and Dosing
In cattle, Prevail is approved only for intravenous (IV) administration. This is an important distinction. While some producers may be tempted to give it intramuscularly or subcutaneously for convenience, those routes are not approved and can cause tissue damage, injection-site lesions, and potential residue violations in meat.
For BRD fever and endotoxemia, the labeled dose is 1.1 to 2.2 mg/kg of body weight, which works out to about 1 to 2 mL per 100 pounds. This can be given as a single daily dose or split into two doses 12 hours apart. Treatment can continue for up to 3 days, but the total daily dose should never exceed 2.2 mg/kg (1.0 mg/lb).
For acute mastitis, the dose is 2.2 mg/kg given as a single IV injection. Unlike the respiratory or endotoxemia protocol, mastitis treatment with Prevail is a one-time dose rather than a multi-day regimen.
Withdrawal Periods for Meat and Milk
If you’re raising cattle for slaughter or milking dairy cows, withdrawal times are critical to staying in compliance with food safety regulations. Cattle treated with Prevail must not be slaughtered for human consumption within 4 days of the last treatment. For dairy operations, milk collected during treatment and for 36 hours after the final dose must be discarded and cannot enter the food supply.
These withdrawal periods exist because flunixin residues can persist in tissue and milk. Violating them is one of the more common reasons cattle producers receive residue violations at processing plants, so careful record-keeping of treatment dates and doses is essential.
Why IV-Only Matters
The IV-only restriction on Prevail in cattle is not just a technicality. Flunixin meglumine injected into muscle tissue is a well-documented cause of tissue necrosis, leaving hardened, discolored lesions that must be trimmed at slaughter. These lesions represent both an animal welfare concern and an economic loss. Beyond tissue damage, intramuscular or subcutaneous injection changes how the drug is absorbed and cleared, which can extend residue times beyond the labeled withdrawal period. The labeled 4-day meat withdrawal and 36-hour milk withdrawal only apply when the drug is given intravenously as directed.
Prevail Paste vs. Prevail Injectable
Prevail also comes in an oral paste formulation, but that product is labeled for use in horses only, not cattle. The paste and the injectable contain the same active ingredient (flunixin meglumine) but are approved for different species. If you’re treating cattle, the injectable solution administered IV is the correct product. Using the horse paste in cattle would be an off-label use with different absorption characteristics and no established withdrawal times for beef or milk.