Piroxicam for Dogs and Cats

By Dr Duncan Houston

Piroxicam is an older non-steroidal anti-inflammatory drug, but it still has a very specific and important role in veterinary medicine. These days, it is used less often as a routine arthritis drug because newer veterinary NSAIDs are usually preferred for day-to-day pain control. Where piroxicam still stands out is oncology, especially in dogs with transitional cell carcinoma, now more often called urothelial carcinoma, where it has documented anti-tumor activity and may be used on its own or as part of a broader treatment plan. (Merck Veterinary Manual)

In practice, this is not a medication to use casually. Piroxicam can be genuinely useful, but it has a narrower comfort zone than many owners realize. The real issues are stomach ulceration, bleeding, kidney injury, and dangerous combinations with other NSAIDs or steroids. (Merck Veterinary Manual)

Quick Answer

Piroxicam is an NSAID used in dogs and, more cautiously, in cats for pain, inflammation, and most importantly certain cancers, especially canine urothelial carcinoma. It can be effective, but it carries significant risks, particularly gastrointestinal ulceration, bleeding, and kidney injury. The biggest safety rules are never combine it with another NSAID or corticosteroid, monitor closely for vomiting, black stool, or appetite loss, and treat any signs of gastrointestinal bleeding or severe lethargy as urgent. (Merck Veterinary Manual)

What Is Piroxicam?

Piroxicam is a prescription NSAID. Like other drugs in this class, it reduces inflammation by affecting cyclooxygenase pathways. In veterinary medicine, it has been used both for chronic pain and for certain carcinomas, particularly urothelial or transitional cell carcinoma in dogs. Merck specifically notes that piroxicam has been shown to reduce the size of tumors such as transitional cell carcinoma in dogs. (Merck Veterinary Manual)

That anti-tumor role is what makes piroxicam unusual. It is not just being used as a painkiller. In the right cancer case, it may also be part of the actual disease management strategy. (Today's Veterinary Practice)

What Is Piroxicam Used For in Pets?

In dogs

Piroxicam is used most commonly for:

• urothelial or transitional cell carcinoma

• some other carcinomas, including squamous cell carcinoma and mammary carcinoma

• selected chronic pain cases when another NSAID is not being used and the case is appropriate (Merck Veterinary Manual)

In cats

It may be used more cautiously and far less commonly. Cats are generally more sensitive to NSAID adverse effects, so the margin for error is smaller. (Today's Veterinary Practice)

In practice, if someone mentions piroxicam in a dog, my brain goes to bladder cancer before arthritis.

Why Is Piroxicam Used for Cancer?

The clearest veterinary evidence is in canine urothelial carcinoma, where piroxicam is one of the most studied NSAIDs. It may be used alone in some palliative cases or combined with chemotherapy drugs in more structured oncology plans. Merck and Today’s Veterinary Practice both describe NSAIDs, especially piroxicam, as useful primary or adjunctive treatments for some cancers in dogs and cats. (Today's Veterinary Practice)

Other tumors where NSAID use has been explored include:

• urothelial carcinoma

• squamous cell carcinoma

• mammary carcinoma

• some nasal and prostatic carcinomas (Merck Veterinary Manual)

The exact anti-tumor mechanism is not fully pinned down, but COX-2 expression and tumor-associated inflammation are part of the reason NSAIDs can be relevant in oncology. (Today's Veterinary Practice)

Is Piroxicam Still Used for Arthritis?

Sometimes, but much less commonly than before. Merck notes that piroxicam is one of the older NSAIDs and that specific COX-2 selective drugs are now generally preferred in many routine pain cases. (Merck Veterinary Manual)

That matters because owners sometimes assume all NSAIDs are interchangeable. They are not. Piroxicam may still be used in selected pain cases, but when it is chosen, there should be a clear reason.

How Is Piroxicam Usually Given?

Piroxicam is usually given by mouth and is commonly dosed once daily or every other day depending on the patient, goal, and tolerance. In dogs with urothelial carcinoma, compounded forms are often used so smaller and more accurate doses can be given, especially in small dogs. Today’s Veterinary Practice notes that compounding is often needed because the commercially available capsule strengths are too large for accurate dosing in many dogs. (Today's Veterinary Practice)

It is generally given with food to reduce stomach irritation, although giving it with food does not eliminate the risk of ulcers or gastrointestinal bleeding. That is an important distinction.

What Side Effects Are Common?

Common side effects

• vomiting

• diarrhea

• reduced appetite

• nausea

• lethargy (Veterinary Partner)

These are the side effects owners are most likely to notice first, and they matter. In a dog on piroxicam, I take appetite loss and vomiting seriously because they can be early warning signs of something more significant.

What Side Effects Are More Serious?

Serious risks include

• stomach or intestinal ulceration

• black, tarry stool

• vomiting blood or dark digested blood

• kidney injury

• bleeding problems

• severe lethargy or collapse (Merck Veterinary Manual)

This is where piroxicam earns its reputation for needing respect. These are not theoretical risks. NSAID-induced gastrointestinal injury can become life-threatening quickly. (Veterinary Partner)

How Worried Should You Be? Severity Framework

Mild

• one episode of vomiting

• mild loose stool

• slightly reduced appetite

• mild nausea but still eating

This should still be reported if it continues, but it may be monitored short term if your pet is otherwise bright and stable.

Moderate

• repeated vomiting

• poor appetite for more than a day

• diarrhea that keeps recurring

• increased thirst or urination

• obvious lethargy

This should prompt a call to your vet and usually a treatment review.

Severe

• black stool

• blood in vomit

• collapse

• severe weakness

• marked abdominal pain

• not eating and clearly deteriorating

This should be treated as urgent.

A very useful decision checkpoint is this: simple stomach upset can happen, but black stool, vomiting blood, or sudden collapse are never routine NSAID side effects. (Veterinary Partner)

Which Pets Need Extra Caution?

Piroxicam should be used much more carefully, or avoided, in pets with:

• kidney disease

• previous stomach ulcers or gastrointestinal bleeding

• dehydration

• clotting or bleeding disorders

• concurrent steroid use

• concurrent NSAID use

• fragile or medically complex cancer cases (Merck Veterinary Manual)

Cats also need more caution because NSAIDs in cats generally have a tighter safety margin.

Drug Interactions That Matter

This is one of the most important sections.

Do not combine piroxicam with:

• other NSAIDs

• corticosteroids such as prednisone or prednisolone (Merck Veterinary Manual)

That combination sharply increases ulcer and bleeding risk.

Use extra caution with:

• clopidogrel or other antiplatelet drugs

• SSRIs and tricyclics that may affect bleeding risk

• methotrexate

• cyclosporine

• some chemotherapy protocols where the interaction is intentional but needs close supervision (Today's Veterinary Practice)

In oncology, piroxicam is sometimes deliberately combined with chemo drugs. That is very different from a home owner casually mixing medications because “they all came from a vet once.”

What Could Look Like a Piroxicam Problem but Be Something Else?

Not every vomiting dog on piroxicam is having a piroxicam reaction.

Other possibilities include:

• progression of the underlying cancer

• kidney injury from another cause

• pancreatitis

• another medication causing nausea

• dietary indiscretion

• unrelated gastrointestinal disease

That said, if a pet on piroxicam develops vomiting, black stool, appetite loss, or lethargy, I would still treat the NSAID as part of the immediate concern until proven otherwise.

When Is This an Emergency?

Seek urgent veterinary care if your pet:

• vomits repeatedly

• has black or tarry stool

• vomits blood

• collapses

• becomes profoundly lethargic

• stops eating and rapidly worsens

• seems painful in the abdomen

• has much less urine output or signs of severe kidney trouble

This is especially important in cancer patients because it is easy to assume “the cancer is just progressing” and miss an NSAID complication that needs immediate action.

What Should You Do Next?

If your pet has just started piroxicam

• confirm exactly why it is being used

• ask what side effects are expected versus concerning

• make sure no other NSAID or steroid is still onboard

• ask when bloodwork should be rechecked

If your pet seems mildly off

• monitor appetite, vomiting, stool color, energy, and water intake

• give the medication exactly as prescribed

• contact your vet if signs continue or worsen over the next 24 hours

If your pet becomes clearly unwell

• stop and contact your vet promptly

• seek urgent care for black stool, vomiting blood, collapse, or major lethargy

• do not give any other pain reliever at home unless you are specifically told to

Common Mistakes Owners Make

1. Combining it with another NSAID

This is one of the biggest avoidable risks.

2. Giving it with steroids

Also a major red flag.

3. Assuming food makes it fully safe

Food may help tolerance, but it does not remove ulcer risk.

4. Ignoring reduced appetite

In a pet on piroxicam, that matters.

5. Assuming vomiting is “just the cancer”

Sometimes it is. Sometimes it is the drug. Either way, it needs review.

Can Piroxicam Be Part of a Long-Term Plan?

Yes, especially in cancer cases, but only with monitoring. Bloodwork is often recommended before and during treatment to watch kidney values and overall tolerance. In some dogs with urothelial carcinoma, piroxicam becomes a core part of palliative care or combination therapy, but it should not be treated as a casual forever drug without follow-up. (Today's Veterinary Practice)

Will My Pet Be Okay?

Many dogs do benefit from piroxicam, especially in urothelial carcinoma where it can provide meaningful anti-tumor and palliative support. But benefit has to be balanced against risk. Mild stomach upset may be manageable. Gastrointestinal bleeding, kidney injury, or severe lethargy are not. (Merck Veterinary Manual)

The practical question is not “is piroxicam good or bad?” It is “does this patient have a strong enough reason to use it safely?”

FAQs

What is piroxicam used for in dogs?

Most commonly for urothelial or transitional cell carcinoma, and less commonly for selected pain or inflammatory cases. (Merck Veterinary Manual)

Is piroxicam a pain medication or a cancer drug?

Both, but in modern veterinary practice its most distinctive role is in oncology, especially canine urothelial carcinoma. (Merck Veterinary Manual)

Can piroxicam cause stomach ulcers?

Yes. This is one of the most important risks. Black stool, vomiting blood, or appetite loss should be taken seriously. (Veterinary Partner)

Can piroxicam be used with prednisone?

No, not unless a veterinarian is managing a very specific plan. Combining NSAIDs with corticosteroids greatly increases gastrointestinal risk. (Merck Veterinary Manual)

Is piroxicam safe for cats?

It may be used more cautiously in cats, but the margin for safety is tighter and vomiting is a more common concern. (Today's Veterinary Practice)

What should I watch for at home?

Vomiting, diarrhea, appetite loss, black stool, lethargy, increased thirst, and any signs of weakness or collapse. (Veterinary Partner)

Why is piroxicam used for bladder cancer in dogs?

Because it has documented anti-tumor activity in canine urothelial carcinoma and may help on its own or alongside other cancer treatments. (Merck Veterinary Manual)

Does giving piroxicam with food make it safe?

It may reduce stomach upset, but it does not eliminate the risk of ulcers or bleeding. (Veterinary Partner)

Final Thoughts

Piroxicam still matters in veterinary medicine because it does something unusual for an NSAID. In the right dog, particularly one with urothelial carcinoma, it can be part of real cancer management rather than just pain control. That is the upside. The downside is that it is not especially forgiving when used carelessly.

If your pet is eating, comfortable, and tolerating the medication well, that is reassuring. If there is vomiting, black stool, loss of appetite, or sudden weakness, the plan needs review immediately, not tomorrow, not after “one more dose.”

If you need help deciding whether piroxicam is appropriate, whether side effects look expected, or whether your pet’s signs are crossing into urgent territory, ASK A VET™ can help you work through that more clearly.