Piroxicam is a drug used in dogs for the treatment of certain cancers. It may sometimes be used to treat pain and inflammation due to arthritis, but this is less common. Piroxicam may also be referred to by its trade name, Feldene.
What Does Piroxicam Do?
Piroxicam is a non-steroidal anti-inflammatory drug, also known as an NSAID. It is in the oxicam class of NSAIDs and is a nonselective COX inhibitor, meaning it inhibits both COX-1 and COX-2. Cyclooxygenase, or COX, is a family of enzymes called isozymes. Each type produces prostaglandins, which are lipids in the cells of the body that have hormone-like effects.
The prostaglandins produced by COX-1 impact homeostasis, a term that describes the equilibrium that supports bodily functions. COX-1 impacts kidney function, the gastrointestinal system, and blood clotting.
COX-2 prostaglandins are increased when inflammation is present in the body and facilitate pain, swelling, and fever.
The drug relieves pain and inflammation, but it can also affect processes related to homeostasis, potentially leading to undesired side effects.
In addition, piroxicam has been shown to have anti-tumor effects and is used to treat certain cancers in dogs. The process by which piroxicam affects tumors is not completely understood; it is believed that it prevents the growth of new blood vessels and promotes cell death in certain tumors.
Piroxicam is not commonly used to treat pain and inflammation in dogs as there are more effective NSAIDs available. Its most common usage is to treat responsive types of cancer.
Diseases/Issues Piroxicam Can Treat
Piroxicam is sometimes used to reduce inflammation and relieve pain associated with conditions like osteoarthritis. However, it is more commonly used to treat certain types of cancer, especially bladder cancer. Piroxicam for cancer treatment is considered "off-label" or "extra-label" usage, as the drug is labeled for treatment of pain and inflammation.
Piroxicam is most commonly used for cancer of the bladder. It may also be prescribed to treat cancers of the colon, prostate, and mammary glands. The cancer types considered most responsive to piroxicam include transitional cell carcinoma, squamous cell carcinoma, and mammary adenocarcinoma.
Dogs are typically treated with piroxicam as a once-daily dosage. It is recommended that this drug is given with food to decrease the chances of gastrointestinal upset.
Side Effects of Piroxicam Use
Typical side effects of piroxicam are much like the side effects of other NSAIDs.
- Vomiting (with or without blood)
- Diarrhea ((with or without blood)
- Loss of appetite
- Gastrointestinal ulceration and/or bleeding
- Black, tarry stools (digested blood in stool)
- Kidney damage
- Liver damage
- Prolonged or unexplained bleeding/clotting difficulty
- Central nervous system issues (uncommon)
If you notice any side effects in your dog while giving piroxicam, stop the medication and contact your veterinarian right away. If you see profuse bleeding, extreme lethargy, sudden collapse, or other serious signs of illness, you should immediately bring your dog to the nearest open veterinary facility.
Considerations Before Using Piroxicam for Dogs
Before prescribing piroxicam, your veterinarian will probably want to run lab work to assess your dog's organ functions and overall health. Dogs with elevated kidney values or elevated liver enzymes are not ideal candidates for piroxicam. In addition, existing heart problems may be worsened by piroxicam use, so your vet may want to do some specific cardiac tests.
Certain medications should not be taken at the same time as piroxicam. Other NSAIDs (like aspirin, carprofen, meloxicam, deracoxib, and others) should be stopped before starting piroxicam unless your veterinarian recommends differently. This is because the use of multiple NSAIDs at the same time can greatly increase the risks of side effects like GI upset, GI ulceration, liver or kidney damage, and abnormal bleeding. Giving steroids along with piroxicam can lead to the same adverse effects.
Other drugs to avoid include certain antibiotics (aminoglycosides), certain chemotherapy drugs (like cisplatin and methotrexate), diuretics, immunosuppressive drugs (like cyclosporine and tacrolimus), and some antidepressants. Be sure to tell your vet about any medications, supplements, and herbal remedies you are giving to your dog.
Dogs on long-term piroxicam treatment will need routine monitoring. This typically includes blood tests every three to six months to make sure there is no damage to the organs. In addition, dogs should get routine examinations as recommended by your veterinarian. Not only does this allow your vet to look for damage from piroxicam; it also lets your vet monitor the effect on your dog's cancer.
Mohammed SI, Bennett PF, Craig BA, et al. Effects of the cyclooxygenase inhibitor, piroxicam, on tumor response, apoptosis, and angiogenesis in a canine model of human invasive urinary bladder cancer. Cancer Res. 2002;62(2):356-358.