High Dose Firocoxib Pilot Study

Gastroscopic Evaluation of Gastric Mucosa in Horses Treated With Flunixin Meglumine or High-Dose Firocoxib: A Descriptive Pilot Study
Vet Med Sci. 2026 Jul;12(4):e71061. doi: 10.1002/vms3.71061.
Authors
Renato Abrantes de Oliveira 1 , Alexandre da Silva Correa 1 , Francisco Décio de Oliveira Monteiro 2 , Pedro Paulo Maia Teixeira 1
Affiliations

1 Veterinary Medicine Institute, Federal University of Pará, Castanhal, Pará, Brazil.
2 Federal Institute of Tocantins (IFTO), Campus Araguatins, Araguatins, Tocantins, Brazil.

PMID: 42418297
DOI: 10.1002/vms3.71061

Abstract

Background: Equine Gastric Ulcer Syndrome (EGUS) is common in horses, and nonsteroidal anti-inflammatory drugs (NSAIDs) are a known risk factor for gastrointestinal ulceration. Although COX-2 selective NSAIDs such as firocoxib theoretically offer a better safety profile, endoscopic evidence for their mucosal safety at high off-label doses is lacking.

Objectives: To compare the effects of label-dose flunixin meglumine and high-dose firocoxib on the gastric mucosa of a small selected group of horses using serial gastroscopy and histopathology in a descriptive pilot study.

Methods: Twenty mixed-breed horses were allocated non-randomly to control (n = 10), flunixin meglumine (1.1 mg/kg IM, n = 5), or firocoxib (1.0 mg/kg PO, n = 5) groups, treated once daily for 5 days. Gastroscopic evaluation and histopathological analysis were performed before (Day 1) and after treatment (Day 6).

Results: No glandular disease was observed. Low prevalence of pre-existing squamous lesions was found in all groups without progression after treatment. Histopathological scores revealed baseline incomparability, with marked cellular infiltrate present only in the flunixin group at Day 1 (60%). Within-group analyses showed no significant changes between time points (p > 0.05). The use of NSAIDs effectively resolved lameness.

Conclusions: In this small descriptive pilot study, limited by non-randomised allocation and small sample size, the study found no detectable short-term gastric mucosal injury associated with high-dose firocoxib within the limits of this study. Due to the non-randomised design, no causal conclusions can be drawn. These hypothesis-generating findings require confirmation in adequately powered randomised trials.

Keywords: NSAID; equine; firocoxib; flunixin meglumine; gastric ulcer; gastroscopy; histopathology.

© 2026 The Author(s). Veterinary Medicine and Science published by John Wiley & Sons Ltd.

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