Association Between Nonsteroidal Anti-Inflammatory Drugs and Gastric Ulceration in Horses and Ponies

Abstract

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely employed in equine medicine to treat acute and chronic inflammation in tendon, ligament and musculoskeletal injuries, as well as after surgery (Cunningham & Lees, 1994; Lees et al., 2004; Dirikolu et al., 2008). These drugs are used because of their analgesic, anti-inflammatory, and anti-pyretic properties; they are also used as adjuvant therapy in the treatment of endotoxemia and to suppress platelet aggregation (Johnstone, 1983; MacAllister, 1994; MacAllister & TaylorMacAllister, 1994; Mathews, 2002). An ideal anti-inflammatory drug is potent and has few adverse effects. In fact, several of the commonly used NSAIDs have a narrow safety margin. It is imperative, therefore, to administer a correct dose at adequate intervals. Thus, use of these drugs for controlling pain in equine is recommended for well-hydrated animals aged over six weeks with normal oncotic pressure. Kidney and liver function should be normal, there should be no signs of gastric ulcers, and the animals should not be taking corticosteroids. Furthermore, two or more NSAIDs should not be given at the same time (Mathews, 2002). It is essential to study in depth the adverse effects, the pharmacokinetics and pharmacodynamics of NSAIDs because of their side effects. The half-life of substances differs among species as a function of biotransformation pathways, drug metabolization time, associated disease (especially renal and hepatic conditions), age (younger animals have immature hepatic enzyme systems, whereas older animals have less efficient kidneys and livers), binding of NSAIDs to food components in the gastrointestinal tract, and association of NSAIDs with other drugs. Studies on the relation between NSAIDs and gastric ulcers in equid species are complex because several factors may cause gastric injury: the physiological status of the stomach; a pH often below 2 (Murray, 1997, 1999); prolonged fasting (where the pH may be as low as 1.55) (Murray & Schusser, 1993); intense exercising in sports animals [which increases abdominal pressure, decreases stomach volume, and results in reflux of small intestine acids into the nonglandular mucosa (squamous mucosa) of the stomach] (Vatistas et al., 1999a; Lorenzo-Figueira & Merritt, 2002; McClure et al., 2005); diseases that cause loss of appetite