Painkillers and Gastric Ulcers in Horses, AAEP 2009

If you've ever given the common oral non-steroidal anti-inflammatory drug phenylbutazone (Bute) to a horse, you've probably been warned that it can cause stomach (gastric) ulcers if you give too much or give it for too long. Thus, there's always interest in pain-relieving medications for horses that work while causing less gastric irritation or none at all.

Suxibuzone is a medication often given to horses because the horse's body converts it to phenylbutazone, theoretically giving it all the anti-inflammatory and pain-relieving effects of phenylbutazone while minimizing stomach irritation. However, a study presented at the 2009 American Association of Equine Practitioners Convention, held Dec. 6-10 in Las Vegas, Nev., might have disproved that theory, at least for recommended dosages.

Frank M. Andrews, DVM, MS, director of the Equine Health Studies Program at Louisiana State University, reported that for the study, 18 horses were housed in stalls, fed sweet feed and hay twice daily, and given omeprazole for eight days before anti-inflammatory medication was given to reduce any pre-existing ulcer scores. Horses were then divided into three groups for a 15-day medication period:

  • Group 1 received 2 grams of phenylbutazone twice daily at 12-hour intervals on the first day, then one gram twice a day.
  • Group 2 received 3 grams of suxibuzone twice daily at 12-hour intervals on the first day, 1.5 grams twice daily on days 2-4, then 1.5 grams once daily for days 5-15.
  • Control group, receiving no medication.

Just before the medication phase, one horse randomly assigned to the phenylbutazone group had an ulcer score of 1, while the rest scored 0. After 15 days of treatment, all treated and control horses had similar median ulcer scores, indicating that at these dosages, suxibuzone was no better for the stomach than phenylbutazone.

"Suxibuzone protection is more likely to be observed when these drugs are administered at higher dosages or to young or debilitated animals," noted Andrews, citing a study that found fewer ulcers in horses given more than double doses of these medications.

"In conclusion, the findings of this study suggest that both top-dress formulations were readily consumed and that neither formulation resulted in excess gastric ulceration when administered per label recommendations," he noted. "Furthermore, no protective effect on gastric mucosa was seen for suxibuzone compared with phenylbutazone."

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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