09/01/2026
Please read labels and STOP the “forever” meds…
The NSAID Science — What's Actually Happening Inside Your Horse's Body
The most common NSAIDs I see horses on don't all work the same way. This matters more than most owners realize.
The key is COX selectivity.
There are two COX enzymes:
COX-1 — the "housekeeping" enzyme. Protects the stomach lining, supports kidney blood flow, maintains gut integrity. You want this one working.
COX-2 — the inducible enzyme. Kicks in during injury and inflammation. This is the one medications want to block.
The problem is that older NSAIDs can't tell the difference between them.
Phenylbutazone (bute)
Non-selective. Blocks both COX-1 and COX-2 aggressively. Highest GI and kidney risk of the group. Well-established link to gastric ulcers, right dorsal colitis, and kidney stress — particularly at higher doses or with long-term use.
Flunixin meglumine (Banamine)
Also non-selective. Commonly used for colic and acute pain. Strong anti-inflammatory effect but also strong COX-1 suppression. Particularly associated with right dorsal colitis when used repeatedly.
Firocoxib (Previcox / Equioxx)
The most COX-2 selective of the group. Theoretically spares more COX-1, which is why it's often described as "easier on the gut." And relatively speaking, it is! But COX-2 selective still suppresses protective prostaglandins. It is not ulcer or kidney damage-free. And the FDA label still says 14 days.
Speaking of that label — this is not my opinion. This is the Equioxx label itself:
"Extended use beyond the label can still carry risks of side effects, including kidney and gastrointestinal damage, requiring professional health monitoring and periodic bloodwork."
And the manufacturer's own list of possible side effects:
→ Sores on the mouth, face, or lips
→ Mouth or stomach ulcers
→ Right dorsal colitis — presenting as diarrhea, dehydration, lethargy, decreased appetite, dark mucous membranes, and/or increased heart rate
→ Kidney disease
→ Diarrhea or loose stools
→ Black or tarry stools
→ Loss of appetite
→ Low blood protein levels — presenting as weight loss or limb swelling
→ Jaundice — yellowing of the gums, skin, or eyes
Read that list again.
How many of those have you noticed in your horse and attributed to something else? Ulcers. Weight loss. F***l Water/Loose stools. Lethargy. Decreased appetite. Leg swelling. Comment Below!
The label lists them because they happen often enough to document. The label also says treatment should be stopped if these signs appear — which means the expectation is that someone is watching closely enough to notice.
Is someone watching your horse that closely? In my practice I very seldom see monitoring of horses on these medications long term. I have clients who are on their 3rd gastroscope in horses that aren't "responding" to ulcer treatment but they are on daily NSAIDS. I have had clients with horses go into kidney failure in their early or mid teens. I see horses with chronic diarrhea and f***l water, and no one is considering the NSAIDS. I see horses with chronic back pain over their kidneys and when the NSAIDS are stopped, it goes away.
THIS is why I am talking about this and sharing MY experience.
"My vet switched us to Previcox because it's gentler" is a meaningful clinical decision. But it doesn't change the fundamental issue. The signal is still being turned down. The root cause is still there.
The question isn't which NSAID is safest.
The question is why your horse needs one at all — and whether that's been seriously investigated. Sometimes the answer is YES! And long term NSAIDS are the best choice. But not always, and its not what I am seeing the majority of the time in my practice. The most common use I see doing damage in my practice is for mild to moderate arthritic or "undiagnosed" pain in young to middle aged horses.
And the GOOD news is there is often things you can do to help manage your horses pain and inflammation other than long term medication- you just haven't tried it yet.
Save this and share it with your barn community. Later this week I'm getting into what some options are you may not have considered.
I support horse owners who want options beyond medication a more supported, whole‑horse approach.
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