Bute is one of the most common medications given to horses. However, horse owners should be well aware of the health risks associated with this drug.
Very young and very old horses are at greater risk of side effects from phenylbutazone. As with any drug, caution should also be used in horses that are sick or under stress. Bute should not be combined with other anti-inflammatory drugs, such as aspirin or banamine, or used in conjunction with herbs that can influence clotting time, such as hawthorn, salvia, angelica, ginkgo, feverfew and ginger. Use bute with extreme caution in a horse with a history of kidney or bowel problems, and with medications that can have negative effects on the kidneys, such as the antibiotic gentamicin.
Bute, short for phenylbutazone, is probably the most widely used drug in horses. Bute is an inexpensive and highly effective treatment for inflammation and pain that can be injected intravenously or given orally to horses as a powder or paste. Bute works by inhibiting a class of enzymes called cyclo-oxygenases, COX for short. Activation of this system is a necessary step in the complex chain of events that leads to inflammation.