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

Different Pain, Different Drugs

Updated: May 15th, 2024

drugs for dog cancer painIn some ways physicians have it easy.  An MD can ask a human patient, “Are you in pain?”

It’s a bit tougher for us animal lovers. Interestingly, we are in the same boat as pediatricians in this way.  We have to go by signs, feelings, intuition in some cases.  And sometimes the truth is that it really can be tough to tell.

The bottom line is that we do know that, obviously, dogs do feel pain.  And that cancer is capable of causing pain in some cases, and definitely later in the disease.

In humans, pain is the most common first complaint of cancer patients, seen in 20-50% of cancer patients when they are first diagnosed.  For late human cancers, 75-90% of patients report pain, often severe.  Therefore, many times a veterinarian or oncologist will prescribe pain drugs.

In light of the fact that so many readers of this blog are giving their four legged family members pain medication, I thought it might be useful to go over the most common of these drugs, at least in terms of what they are used for.

Sometimes a dog lover will get a medication with the comment, “This is for pain.” Okay, makes sense.  But as usual, there is more to the story.

There are different kinds of pain, and the medications for pain work in different ways.  Certain pain medications are better for certain kinds of pain.

One of the central themes of The Dog Cancer Survival Guide is to help you be a better Guardian for your dog. A guardian is a vigilant protector. In order for you to be a vigilant protector, you must be armed with the data and concepts you need to fulfill the job requirements.

Okay, here’s some data and concepts for you.

First, the NSAIDS (Non Steriodal Anti Inflammatory Drugs).  Examples are Metacam, Deramaxx, Previcox, Rimadyl, aspirin, and Tylenol (not often prescribed in primary care).

These drugs lessen inflammation, which is often seen as redness, swelling and discomfort.  They also have a second effect called analgesia, which is the medical word for pain reduction.

These drugs are used for pain that is mild to moderate in humans, and we should likely apply this information to dogs.  For obvious signs of pain in dogs (more severe), these drugs by themselves are often not enough.

The NSAIDS are useful for controlling what is called adaptive pain, which means the body’s response to tissue injury, in this case caused by cancer.  Adaptive pain can also be caused by trauma, surgery, and so on.

(By the way, I receive a lot of questions about the use of Apocaps with NSAIDs.  The substances in Apocaps are found in plants, but have been shown to have actions that are similar to the NSAID drugs, although they are gentler and take a week or two to build up in the system.  For this reason, in my patients, I will drop the dose of either the NSAID or the Apocaps to 1/4-1/2 the labeled dose when they are used together.  I also do not use them together if the patient has a history of a sensitive stomach.)

If the adaptive pain is more severe, vets will often combine drugs. This is called multimodal analgesia, which is a strategy to control pain using drug combinations.  This allows for more pain control while minimizing side effects that happen if we keep increasing single drug doses.

Typically, a narcotic of some kind is used with an NSAID.  Some examples would be sustained release morphine or Tramadol (pills) or Fentanyl (usually a patch delivering the drug through the skin).  Strangely, morphine has some evidence for increasing cancer cell growth.

However, there is a lot of variability in how different patients respond to these drugs, and in end-stage cancer, if the morphine is helping a lot with life quality, it may be the best choice from a humane standpoint.

It is interesting that Tramadol may have some anti-depressant effects, which is quite nice for a cancer patient, dogs included.

There are actually true anti-depressants which may help with cancer pain.  One is amitriptyline (Elavil).  This medication is not used for adaptive pain.  There is another type of  pain that has nothing to do with tissue injury per se.  It involves the reaction of the nervous system (brain, spinal cord and nerves) to the tissue injury.

This type of pain is called nueropathic pain, and is an independant part of the overall pain experienced.  It is actually the body’s response to adaptive pain, and it adds to the overall experience of pain in a real way. In some cases it is called “wind-up”. Sometimes neuropathic pain can be caused by anxiety.

In neuropathic pain, the reaction in the nervous system to the pain actually makes the pain feeling worse.  We see this more common in pain that is experienced for a long time on the order of weeks, months or years (chronic pain).

Medications like Elavil can help with this type of pain.  Other medications that help with the neuropathic part of chronic pain include Gabapentin and Amantadine.

Usually we will combine the drugs used to treat neuropathic pain with medications for adaptive pain.

Other ways to help with cancer pain include acupuncture, palliative radiation, and pamindronate. Discuss these with your conventional veterinarian, oncologist, or holistic vet to see if they are appropriate for your dog’s cancer.

For those of you having the misfortune of having Torbugesic as the med your vet first prescribes for your dog’s pain, please insist on getting something longer lasting and more potent. This drug last only about 1-2 hours in dogs and, at least in my hands, is almost useless for significant pain control.

Pain control is an important part of the full spectrum cancer plan discussed in The Dog Cancer Survival Guide.


Dr D

Leave a Comment

  1. A Dog With Bone Cancer on October 6, 2010 at 6:16 pm

    […] goodness for high quality pain control.  Thank goodness she was on Apocaps. Thank goodness she is blessed with a will to […]

  2. anne on August 28, 2010 at 9:30 am

    my maxwell(rotweiler) (MY BEST FRIEND) was diagnosed with bone cancer last Oct. and had an amputation of right front leg. The only signs I saw from him was a limp. After the surgery and even before the surgery he never showed he had pain of any kind. Now two weeks ago he was diagnosed with cancer in both back legs. One worst then the other. Obviously we can’t amputate those legs. I am having a very hard time dealing with this. My one concern is he never shows or tells me he is in pain. I just take one day at a time . I will count on him to tell me when it is time. I have had this dog since he was 4 wks old. He is 7.5 now which seems unfair being so young. This dog and I have quite a history. And to all going through or have gone through this pain My heart goes out to you. Maybe one day cancer in dogs and humans will be able to be cured. I lost both my parents to cancer. My mother most recently.

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