Naproxen is similar in structure and pharmacologic profiles as ibuprofen and ketoprofen. Though it has been used in equine medicine for some time, wide spread use has not come yet. Perhaps this is due to the cheaper alternative phenylbutazone. This is a shame, as experimental work suggests it may be more effective at less toxic doses for musculoskeletal pain in horses. This article is about the contraindications, toxic effects, dosages, and association drug rules that apply to this medication.

Naproxen is a propionic acid derivative and in the same family of drugs as ketoprofen and carprofen. Like other NSAIDs, naproxen has analgesic, anti-inflammatory, and antipyrexic activity. It is used much less than phenylbutazone for musculoskeletal conditions. Though originally marketed for muscular conditions it is very useful in other painful conditions with the possible exception of colic. Naproxen has relatively close anti-inflammatory and analgesic doses and it would therefore be expected to have a greater anti-inflammatory effect than drugs such as phenylbutazone and aspirin. Work has demonstrated that naproxen does indeed seem to be more effective than phenylbutazone in an experimental model of equine myositis. In clinical cases of azoturia, naproxen produced a favorable response in 90% of horses with an average time for remission of five days.