Dipyrone for Horses

Commonly prescribed for: Fever Reduction, Mild Colic, and GI Pain

Species: Horses

Therapeutic Class: Nonsteroidal Anti-inflammatory

Dipyrone (metamizole) is a nonsteroidal anti-inflammatory drug. The mechanism of action of dipyrone is thought to be similar to that of other NSAIDs: inhibition of the production of prostaglandins. It commonly is used in the horse as an antipyretic, analgesic and anti-inflammatory.

Dipyrone is a very mild NSAID. Because of its very mild analgesic properties it is unlikely to mask abdominal pain due to a surgical problem. Traditionally, dipyrone has been thought also to have anti-spasmodic properties on the smooth muscle of the gastrointestinal tract, which has been the basis for its common use in cases of mild colic. Although research evidence does not support any claim of anti-spasmodic activity, many clinicians consider it a very useful drug precisely for this reason. Flunixin meglumine is an NSAID with stronger analgesic properties that also is used to treat GI pain.

Dipyrone may be used in foals and in adult horses to reduce fevers. It is not used commonly to treat musculoskeletal pain. Dipyrone may be given IM, IV or subcutaneously.

• The most-common side effect for dipyrone is injection-site reactions. These reactions usually respond to hot compresses and NSAIDs.
• Prolonged use of dipyrone may cause bone-marrow suppression (leukopenia, agranulocytosis). Animals receiving prolonged courses of dipyrone should be followed with regular CBCs.

• Although dipyrone is a very mild NSAID, these types of drugs should be avoided or very carefully monitored in animals with liver disease, kidney disease or GI problems. Therapy should be stopped at the first sign of any adverse reaction such as anorexiaoral ulcers, depression, decreased plasma protein, increased creatinine, anemia or leukopenia.
• Dipyrone should be given slowly when used intravenously. Rapid administration may cause seizures.
• Dipyrone should be used with caution in older or debilitated animals particularly those with cardiac disease.
• Dipyrone should not be used in animals with a history of blood or bone marrow abnormalities.
• Dipyrone once was considered a "masking drug" in racehorses. If used in racehorses, inquiry should be made with the individual racing jurisdiction regarding withdrawal periods. Older information suggests a five-day withdrawal period.

• Dipyrone should not be used concurrently with chlorpromazine due to potentially serious hypothermia.
• Dipyrone should not be used in conjunction with phenylbutazone or barbiturates.

Convulsions have been reported following acute overdose.