Study Hard On Bute, Aspirin

Bute can cause sores on a horse’s lips after long-term use (note white spot on lip). Aspirin may be a better choice for laminitic horses than bute.

We all know that the long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs), like bute, especially in high doses, may cause intestinal ulceration and kidney damage. However, there’s more reason for concern, and we need to take the warnings about the potentially harmful effects of treating arthritis with NSAIDs seriously.

A study at Ohio State (Beluche et al), appearing in the American Journal of Veterinary Research, examined the effect of 14 days treatment with phenylbutazone on joint cartilage proteoglycan synthesis, compared to untreated controls. Joint cartilage was biopsied from the horses before treatment, after 14 days of bute, and again 14 days after the bute stopped. The researchers found a significant depression of joint cartilage synthesis in the treated horses both at the end of two weeks of treatment and when resampled two weeks after treatment stopped. ”Phenylbutazone should be used judiciously in athletic horses with osteoarthritis,” they said, concluding that the bute can interfere with the ability of the cartilage to both repair and maintain itself.

A review of the effects of NSAIDs at the Indiana University School of Medicine states that both salicylates (aspirin) and other NSAIDs have a variety of harmful effects on cartilage that are even worse when arthritis is present because of higher concentrations of the drug occurring in inflamed joints. A similar study (Rhode et al) looked at the effects of bute on bone. It found bute decreased the rate at which mineral was deposited in bone defects and appeared to slow the rate of healing. We need to take the warning about the potentially harmful effects of treating arthritis with NSAIDs seriously.

NSAIDs inhibit the growth of new capillaries. The growth of new blood vessels into an injured area is a critical part of the repair process. In addition, NSAIDs can interfere with the natural balance between normal levels of vasodilating chemicals and vasoconstricting ones with the result being decreased perfusion of the tissues and higher vascular tone/spasm. This combination could have negative effects in conditions like chronic laminitis. Aspirin, on the other hand, can selectively block endothelin receptors and improve circulation.

Bottom Line
Both aspirin and bute can have negative effects on healing and joint cartilage. These drugs should be limited to the lowest dose possible and the shortest time frame possible.


Joint nutraceuticals and antioxidant vitamins and minerals are a better way to support the arthritic horse, combined with regular light exercise and local treatments. It remains to be seen if any herbal has a direct effect on joint metabolism, although the few that have been studied don’t have these effects.

The circulatory drawbacks of NSAIDs are of most concern with laminitis, where impaired circulation and damage to the blood supply of the foot are major considerations. Aspirin is a better choice for laminitis both for this reason and because of the mild antiplatelet effect.

A study using AspirEase (Bio-Nutrition Labs), a microencapsulated, buffered aspirin for horses, found that chronic joint pain may respond to a dose as low as 5 mg/kg twice a day, although no study was made of laminitis pain. The product is sold through Walco as EquiSpirin, and through vets as Arthraban on the Vedco label.

For horses with laminitis, we’ve found Uckele Health and Nutrition’s PhytoQuench (, 800-248-0330) may eliminate the need for bute. This herbal mixture contains a number of herbs believed to be circulation-enhancing and antiplatelet.