-Katey Campbell, KC Equine Wellness
NSAIDs like Previcox and Equioxx (firocoxib) are some of the most commonly used pain medications in the equine world, yet they are also some of the most misunderstood and misused. In human medicine, we already recognize that long‑term NSAID use can damage the stomach, kidneys, and liver, and these drugs are meant for short‑term relief, not daily, indefinite use. Horses are no different. Their internal systems are even more sensitive, yet I see NSAIDs used casually, continuously, and often without owners being informed of the risks. Most owners are simply trying to help their horses feel better, but they were never told what these medications actually do inside the body. I will talk about it later on, but there are certain situations where long term use is warranted, however I see prolonged use in young horses far to often.
Although firocoxib (Previcox/Equioxx) is often promoted as “safer” than bute, it’s important to understand what that actually means. Firocoxib is a COX‑2 selective NSAID, which means it primarily targets the COX‑2 enzyme responsible for inflammation and pain, while sparing more of the COX‑1 enzyme that protects the stomach lining, kidneys, and gastrointestinal tract. This selectivity does make it easier on the stomach than bute, which is a non‑selective NSAID that blocks both COX‑1 and COX‑2 and is well‑documented to cause gastric ulcers, with research showing up to 80% of horses on long‑term bute developing some degree of gastric ulceration. But “easier on the stomach” does not mean “safe for long‑term use.” Even COX‑2 selective drugs still reduce protective prostaglandins, still impair blood flow to the kidneys, still stress the liver, and still damage the hindgut when used beyond short‑term recommendations. The manufacturer’s own label reflects this reality: Equioxx is not intended for use beyond 14 days, and prolonged use increases the risk of internal damage despite being gentler than bute on the stomach. COX‑2 selectivity reduces one category of harm, it does not eliminate the systemic risks that come with chronic NSAID exposure.
The long‑term effects of NSAIDs on the body are significant. They reduce blood flow to the kidneys, which over time can impair filtration, stress the kidneys, and contribute to chronic kidney disease. They place a heavy burden on the liver, which must metabolize the drug while also managing detoxification, hormone regulation, and nutrient processing. NSAIDs also reduce the protective mucus layer in the stomach, increasing the risk of gastric ulcers. Even COX‑2 selective drugs like firocoxib can contribute to ulcer formation, especially when used beyond recommended durations. Phenylbutazone (bute) is even harsher: studies show that long‑term bute use can cause gastric ulceration in up to 80% of horses, along with right dorsal colitis and significant hindgut irritation.
The hindgut is where NSAID damage becomes even more concerning. These drugs can disrupt microbial balance, damage the mucosal lining, and increase intestinal permeability (“leaky gut”). Hindgut pain is invisible, but it is real, and often far more severe than the musculoskeletal discomfort owners are trying to treat. This is where the emotional component comes in: humans don’t want to see their horses uncomfortable. Musculoskeletal pain is visible, stiffness, short strides, reluctance to move. Internal pain is not, ulcers, kidney stress, liver overload, microbial imbalance. So we medicate what we can see, while unintentionally worsening what we can’t.
Another major issue I see constantly is drug stacking, using NSAIDs alongside other medications that also stress the gut, liver, or kidneys. This includes stacking NSAIDs with steroids, muscle relaxants, ulcer medications, sedatives, or multiple NSAIDs at once. Every added drug increases the metabolic and toxic load and reduces the body’s ability to protect itself. The most concerning pattern is when horses are on long‑term ulcer medication while simultaneously being kept on NSAIDs. This is very detrimental. Ulcer medications suppress stomach acid, alter digestion, and change microbial balance. NSAIDs reduce protective mucus, impair blood flow, and increase inflammation internally. Together, they create a chronic cycle that wreaks havoc on the gut, liver, and kidneys. I see horses stuck in this loop for months or years, and owners have no idea why their horse never fully improves.
The truth is that long‑term NSAID use often causes more inflammation and damage than the original pain owners are trying to medicate. Over time, these drugs damage the gut, increase systemic inflammation, impair nutrient absorption, and stress detoxification pathways. The very thing owners are trying to reduce, pain and inflammation, becomes worse because the internal systems responsible for healing are being harmed.
Short‑term or intermittent use can absolutely be appropriate. Acute injuries, post‑surgical pain, flare‑ups, or palliative care are all situations where NSAIDs can be helpful. If your horse is palliative and this medication keeps them comfortable, then comfort is the priority. But even then, it’s important to understand the trade‑offs so you can support the horse in other ways.
What I find most often is that horse owners were never informed of the detrimental effects. They were not told about the 14‑day guideline, the kidney and hindgut risks, the ulcer connection, or the consequences of drug stacking. They were not given alternatives or told what to monitor. This is not the owner’s fault, this is a communication gap in the equine industry.
NSAIDs have a place, but that place is short‑term, intermittent, and carefully monitored. Long‑term use comes with significant risks to the kidneys, liver, stomach, and hindgut, and often creates more inflammation and pain than the original issue being medicated. When we understand the full picture, we can make informed decisions that support both comfort and long‑term health.