Skip to content
Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Chronic Morphine May Worsen Dog Cancer

Updated: December 21st, 2018

Well, in this post I want to give the readers some cutting edge new developments in dog cancer pain control.

For decades, morphine has been a good old standard in pain control, both in dog and human medicine.  Many oncologists and veterinarians involved in treating dogs afflicted with cancer use morphine to help these patients.

New evidence is always arising though, and I would like to share something that may influence the use of this drug.

Get a copy of the Dog Cancer Survival Guide for more helpful tools and information

An article was published that has recently started getting some attention. It contained two main pieces of information.  First, the use of morphine over 2 weeks, in rodents, caused tumors to increase in size, lowered survival times, and increased the spread of tumor cells. Secondly, the use of an anti inflammatory drug called celecoxib blocked this effect.

This is quite alarming for dog lovers giving their dog long-acting morphine to help with pain in osteosarcoma, or other tumor types.

How surprising that the very drug used for pain is likely worsening the cancer. Granted, this was not shown specifically in dogs, nor for all cancers, but it raises very large red flags.  Remember that toxicity tests for human drugs are done on rodents!

In dogs, side effects of celecoxib limit its use unfortunately.

So, what do we do??

Well, like most things, one must look at the big picture. If your loved dog is departing, and morphine is helping, use it all you want.  If you have a dog that is not immediately leaving you, or if you have a dog under its average life expectancy, consider limiting the use of morphine for pain control.

There are lots of other choices.  Talk to your vet about these options:

  • Tylenol with codeine
  • Tramadol
  • anti inflammatory drugs like piroxicam, Deramaxx, Metacam, naproxen and others
  • Gabapentin, which was originally intended for seizure control, also used for pain
  • Elavil, previously commonly used for anxiety, now also used for more chronic pain
  • Amantadine, a newer drug sometimes used for chronic pain

These can all be given at home and improve life quality for our canine companions during these difficult times.


Dr D

Leave a Comment

  1. Ronaldo on June 12, 2009 at 8:16 am

    Science today has changed, I hope you used the right way, because there are medications such as vicodin, oxycodone, Lortab, etc, are anxiolytic and although much help to soothe the pain, can be double-edged weapon to control pain, so indicate in to be confident that this discovery is beneficial to all.

  2. Sharon Festa on April 17, 2009 at 6:43 pm

    We are now grieving the loss of our beloved dog, Sammy, we had for 13 years. I am especially sadden because our Vet, who we adore, chose to give Sammy just Prednisone(as well as kidney meds)because he had liver & kidney problems. He was only suppose to live for a few weeks – that was in late November. After finding your site, I changed his diet, and we just put him down on Monday, April 13. He was such a fighter, my loving dog. I was wondering why he wasn’t on something stronger and now I’m feeling guilty and wish we had asked for stronger meds. I myself am on Morphine daily for severe chronic pain. I just pray our baby boy didn’t suffer needlessly. I trust our Vet and I guess they just didn’t see him lasting this long. He had cancer all through his body as well as hip problems. We treated him like our child and went to the store every 3 days for fresh food for him. After seeing your e-mail, I guess I feel better about the morphine. Thank you Dr. for giving us such wonderful information. We are passionate animal lovers and my husband & I thank you because we feel by changing his diet and giving him wonderful care, he lived longer. I thank you from the bottom of my heart. This puppy hit us hard. He was very special. We have another dog, Luke, who is 12 yrs. old and is totally lost right now. He just keeps going from room to room looking for his buddy. Do dogs know really what is going on? The day we took him, Luke went into the back bedroom of our home when we were leaving which has never happened. Usually, they are both busting out the door to get into the car. We think Lukey is grieving, as we are. Is this possible?? He follows me every time I get up. Lukey is amazingly pretty healthy but I’m worried he will start to fail. Sorry I went on so long. Thanks for listening. Thank you again for your invaluable information on one of “Gods Truly Beloved Creatures.” Sharon Festa & Robert Festa, Pompano Beach, Florida

Scroll To Top