Is Cancer In Dogs Painful?

When I first meet a client and their dog during an oncology consultation, one question that almost always comes up is whether or not their dog is painful.

We never want our dogs to be in pain or uncomfortable, and if they are, we definitely want to know how to fix it.

This article will discuss tumors commonly associated with pain, common signs of pain in dogs, and other ways that cancer can cause dogs to feel poorly.

Knowing what to look for is the first step towards helping your dog feel better.

Tumors Commonly Associated with Pain

Tumors invading bone -

Any tumor that invades bone will be painful. The most common places to have a tumor affecting bone is on the legs, ribs, and in the mouth.

Dogs do a very good job of hiding pain and don't express pain like we do (they don't typically vocalize). If a dog has a tumor that invades bone, they should be on pain medication (even if you don't think they're obviously painful).

You can determine if there is bone involvement using x-rays (radiographs) or CT scan. There must be at least 30% loss of the bone's cortex (outer surface) for an x-ray to pick up any abnormalities. Due to this fact, x-rays might not show any bone invasion, but it might be present (x-rays are not a very sensitive test for this).

Many oral tumors (in the mouth) invade bone and cause pain. If your dog has an oral melanoma or fibrosarcoma, bone invasion is likely (unless the tumor is very small).

If your dog has a tumor near the ribs that feels firm and fixed, and x-ray might be indicated to determine if the tumor is originating from the rib itself. These are painful tumors and do require pain medication (if surgery is not pursued).

Osteosarcoma is the most common bone tumor. This tumor typically affects the extremities (legs), but it can affect any bone in the body. Dogs that have osteosarcoma will be very painful. If their family does not elect surgery, their pain should be assessed every few weeks by a veterinarian to ensure that their pain is managed appropriately. Other modalities such as radiation, bisphosphonates, and acupuncture can improve pain control for these patients.

Large ulcerated skin tumors -

Most skin tumors are not painful, however, if a dog has a very large tumor that is either stretching the skin or is open and has ulcerated, this will be uncomfortable.

Tumors of the gastrointestinal tract -

Gastric (stomach) tumors and tumors involving the esophagus and intestines can also be quite painful; pain medications are indicated for these patients. In many cases tumors involving the gastrointestinal tract cause significant nausea and decreased appetite; these patients can also benefit from a good anti-nausea medication such as Cerenia.

Tumors of the urinary tract and prostate -

If your dog has a prostate tumor, a tumor in the urethra or bladder, these can also be very uncomfortable. Pain medication will make urination and defecation more comfortable for your dog.

Tumors Not Typically Associated with Pain

Skin tumors that are soft and small (not large, open and ulcerated) should not be painful.

Dogs that have lymphoma are not typically painful unless the lymph nodes are severely enlarged or their gastrointestinal tract is affected.

Signs of Pain in Dogs

As mentioned above, dogs will not vocalize when they're painful (unless it's excruciating). We need to be able to notice some of the more subtle (but significant) signs of pain, listed below:

Oral pain: drooling more than normal, chewing using one side of the mouth, taking longer to eat, eating less, pawing at the mouth/face, rubbing the mouth/face onto the floor

Pain involving a limb (ex. bone tumor): limping, favoring the painful leg, licking the painful leg, possibly lethargy, possibly decreased appetite

Pain involving a skin tumor: licking or biting the tumor

Pain from a tumor in the prostate or urinary tract: taking longer to urinate or defecate, straining to urinate or defecate, possibly lethargy or decreased appetite

Abdominal pain: downward dog stretch, increased drooling, decreased appetite, possibly lethargy

Look at the Big Picture...

There are many types of cancers that can cause a dog not to feel well, but that are not associated with pain.

We should routinely monitor for changes that might indicate that our dog is not feeling well.

Many times, signs get brushed off due to old age and 'slowing down'. Even if the new signs and changes are due to arthritis, shouldn't we try to improve their quality of life?

There are many options to help a patient with arthritis:

Top 4 - (1) Anti-inflammatories (2) Low impact exercise to build muscle (3) Optimize weight (4) Optimize omega 3 fatty acid intake

**See The Happy Healthy Dog Guide for a comprehensive discussion

There are also many modifications that can be made at home:

(1) Place runners along hardwood floors (2) Provide soft padded bedding (3) Build muscle with walking/swimming (4) Keep nails short (5) Weight loss.

If your dog has arthritis and you feel that his quality of life is decreasing because of this condition, talk to your vet. If your vet doesn't seem on board with helping you make significant changes, get a second opinion.

Signs of "stomach upset"

Many cancers can cause nausea or soft stool. These two changes can decrease quality of life as much as pain and should be addressed.

It's important to know that vomiting is the last sign of nausea in dogs. Typically, there are more subtle signs of nausea that are displayed before vomiting. If you can learn to spot the first signs of nausea and treat them appropriately, vomiting can be prevented.

Signs of nausea include: decreased appetite, increased drooling, lip-smacking, walking to the food bowl then walking away without eating.

If your dog is exhibiting one of these signs (or more than one), talk to your vet about whether they could be nauseous. If your vet feels that this might be a possibility, they will likely have you try an anti-nausea medication such as Cerenia (maropitant) or Zofran (ondansetron). These are both good anti-nausea medications, which should be given at least 30 minutes before offering food (we want them to begin working before your dog sees/smells food). If your dog doesn't have a diagnosis, hopefully you can pursue a work-up to figure out why your dog is nauseous and fix it.

Do you think your dog might be painful? If so, reach out to your vet, describe the signs that you're seeing, let them know which medications and supplements you're giving (if any), then see what they recommend.

We always want to take the opportunity to improve quality of life if at all possible.

Dr. Lori Cesario

Board Certified Veterinary Oncologist

PS: I'm happy to now offer online oncology consultations. Learn more about how this service can help by visiting the Vet Cancer Consultants site.

A few other articles you might enjoy...

(1) Dog Breeds and Their Associated Cancers

(2) Mast Cell Tumors - The Great Imitator in Canine Cancer

(3) Canine Splenic Tumors - What You Need To Know

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