Horse — Mustang — Flunixin Meglumine Injectable

The most commonly reported adverse reactions in horses involve NSAIDs (particularly phenylbutazone and flunixin meglumine), which can cause gastrointestinal ulcers, right dorsal colitis, and renal toxicity. Antibiotic-associated diarrhea and colitis are also serious risks in horses, as disruption of the hindgut microbiome can trigger life-threatening conditions. Sedatives and anesthetic agents carry risks unique to equine physiology, including post-anesthetic myopathy. Horses are also highly sensitive to certain compounds toxic to other species at normal doses.

Not necessarily. Adverse event reports document that a drug was given and that the animal later died — but they do not establish causation. The animal may have died from its underlying condition, from concurrent medications, or from unrelated causes. The FDA applies a structured causality assessment to each report to determine whether the drug was likely, possibly, or unlikely responsible. Still, all death reports are reviewed and tracked because they contribute to safety signal detection, even when individual causality is uncertain.

You can report a suspected adverse drug reaction to the FDA Center for Veterinary Medicine through the FDA Safety Reporting Portal at SafetyReporting.hhs.gov or by calling 1-888-FDA-VETS (1-888-332-8387). You can also contact the drug manufacturer directly — they are required to forward serious adverse event reports to the FDA. Include the drug name and dose, the animal's species, breed, age, and weight, the duration of treatment, and a detailed description of the symptoms observed and their timeline.