Bute vs Equioxx for horses: anti-inflammatories compared
Phenylbutazone (bute) and firocoxib (Equioxx) are anti-inflammatories for pain and lameness in horses. Bute is inexpensive and powerful but more likely to cause stomach ulcers and colon damage; firocoxib is more selective, given once a day, and approved for osteoarthritis pain.
Updated October 4, 2026
At a glance
- Selectivity
- Phenylbutazone
- Non-selective
- Firocoxib
- COX-2 selective
- Approved for
- Phenylbutazone
- Musculoskeletal pain and inflammation
- Firocoxib
- Osteoarthritis pain and inflammation
- How often
- Phenylbutazone
- Once or twice a day
- Firocoxib
- Once a day
- Digestive risk
- Phenylbutazone
- Higher: ulcers and colon damage
- Firocoxib
- Lower
- Forms
- Phenylbutazone
- Paste, powder, tablets, injection
- Firocoxib
- Paste, tablets, injection
Phenylbutazone bute | Firocoxib Equioxx | |
|---|---|---|
| Selectivity | Non-selective | COX-2 selective |
| Approved for | Musculoskeletal pain and inflammation | Osteoarthritis pain and inflammation |
| How often | Once or twice a day | Once a day |
| Digestive risk | Higher: ulcers and colon damage | Lower |
| Forms | Paste, powder, tablets, injection | Paste, tablets, injection |
How they differ
Bute blocks both forms of the COX enzyme, including the one that protects the stomach and intestines, which is why high doses or long courses can cause ulcers, right dorsal colitis and kidney damage. Firocoxib targets the inflammatory form more selectively, so it is often chosen for long-term arthritis management.
Using them safely
Never give two anti-inflammatories together, including bute with banamine or firocoxib. Make sure your horse is drinking well, since dehydration raises the risk of kidney damage, and report reduced appetite, colic signs, diarrhea or swelling under the belly.
Food and competition rules
Phenylbutazone is prohibited in horses intended for food. Competition rules limit anti-inflammatory use, so check your organization’s rules and withdrawal times before an event.
Long-term arthritis care
Exercise management, weight control, hoof care and joint therapies work alongside medicine, and your vet will aim for the lowest effective dose with periodic checks.
Cost
Bute is inexpensive. Firocoxib usually costs more, so compare prices through your vet or a veterinary pharmacy.
Dosing accurately
Doses are based on weight, so estimate your horse’s weight carefully and set paste syringe rings precisely; overdosing raises the risk of ulcers and kidney damage. Ponies and foals are more sensitive to bute’s side effects. Watch for reduced appetite, dullness, colic, loose manure or swelling along the belly, and call your vet promptly if they appear.
Stomach protection
For horses on longer courses or with a history of ulcers, your vet may add omeprazole to protect the stomach while an anti-inflammatory is needed.
Questions for your vet
- Which suits my horse’s condition and length of treatment?
- Does my horse need stomach protection?
- What are the withdrawal times before competition?
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Sources
Written by the Script Unlock editorial team from the sources above. It is general information, not advice for you or your pet; your vet decides which medicine is right.
Script Unlock is a marketplace that lets licensed pharmacies quote a cash price on your prescription. It does not prescribe, dispense or sell medication, does not process patient payments, and does not give medical advice. Always follow the instructions of your prescriber and pharmacist and read the medication guide supplied with your medicine.