Should a Pet With Cancer Get Chemotherapy?

by Michael Fagan, DVM

“Cancer” is a word that can induce fear and other emotions.  Many people have personal experiences with cancer and chemotherapy that they don’t wish to impose on their pets.  To be sure, cancer and the many treatment options we can offer are not to be taken lightly.  However, we do have many patients that have received treatments for cancer with favorable outcomes, from cures or long term remission to improved quality of life for many months to years.

The most important factor in determining treatment options and recommendations is what type of cancer the pet has developed.  “Cancer” is a very broad term, with many different types and variable response to different kinds of treatment.  Each patient with cancer is unique.  We offer options based on the type of cancer, symptoms or lack thereof, the pet’s overall health, and owner preferences.  Some cancers are best treated by surgical removal.  Others respond best with radiation, chemotherapy, or immunotherapy.  Some have a poor prognosis regardless of treatment, and control of pain or other symptoms takes priority before opting for euthanasia. We will often consult with a veterinary oncologist as we explore the options available.

The goals of treatment are also unique to each patient, but as a general rule, we aim for a cure only if we can preserve good quality of life throughout the process.  More often, we are trying for a long term remission or control of tumor growth for many months to a few years.  The most common treatment for cancers that are not curable with surgery is chemotherapy of one form or another.

Herein lies a vital difference between veterinary and human medicine:  in human medicine, the treatment goal is often to eliminate the cancer and then recover the patient; in veterinary medicine, we want to preserve good quality of life while limiting the cancer.  In other words, we use drugs, doses, and treatment schedules that minimize side effects while still providing the benefit of remission or delayed growth of the cancer cells. 

With chemotherapy, we have had lymphoma patients live longer than two years; bladder cancer patients, one to two years; dogs with nasal tumors, over a year; most with minimal side effects from the chemotherapy and reduction or elimination of symptoms caused by their cancer.  Unfortunately, not all patients respond, and not all tolerate the chemotherapy equally.  Each patient needs to have its treatment protocol customized. 

One relatively new approach to chemotherapy is using small daily doses instead of higher intermittent doses.  This tends to reduce toxicity and has a different effect on tumor growth.  Rather than actively killing tumor cells directly, low-dose daily therapy (called metronomic therapy) may work by reducing the blood supply to the tumor and by allowing the immune system to respond more aggressively. 

The bottom line is that we have many options for treating the many kinds of cancer that we diagnose in pets, including surgery, radiation (by referral to a veterinary oncologist), traditional or metronomic chemotherapy, immunotherapy (there is a vaccine for melanoma!), and/or palliative care (control of pain and other symptoms caused by the cancer). In animals we also have the option of euthanasia when appropriate but that is a subject for another blog. 

National Pet Dental Health Month?

In doing some reading for this month’s posts, I came across a listing of National Pet Holidays.  Did you know January 14 was National Dress Up Your Pet Day, February 23 is National Dog Biscuit Day, and May 30 is Hug Your Cat Day?  These may seem silly or trivial, but there are many national pet “holidays” focused on more serious problems, too:  May 13 to 19 is National Dog Bite Prevention Week and all of April is Prevention of Cruelty to Animals Month.  What I was after, and what I think is really important – so important we’re going to devote several posts to it – is Pet Dental Health Month. Pet Dental Health Month is just around the corner in February. When I was in veterinary school, teeth and the oral health of animals was virtually ignored.  Our dental course was an elective – we weren’t required to take it – and lasted a mere 4 hours.  Compare that to the 70 hours spent studying in fine detail the Krebs or Calvin cycle and other minutia of biochemistry, information I rarely draw on in day to day decision making as a practicing veterinarian.  Fortunately, times have changed and we now recognize how common dental disease is and how significantly disease in the mouth impacts your pet’s overall health.  

So, why do we care about the teeth and disease in the mouth?

The simple answer is, without proper dental care EVERY SINGLE pet we see will develop dental disease at some point in their life.  In fact, according to the American Veterinary Dental Society, up to 85% of dogs have some degree of dental disease by 4 years of age.  Even this young, I have seen advanced periodontal disease in many of our patients.  That means that at what should be the prime of their life, many dogs and cats are already experiencing the discomfort that is common with dental disease.  We also care because of how dental disease can affect your pet as a whole.  A report released by the Surgeon General back in 2000 sums it up nicely: “The terms oral health and general health should not be interpreted as separate entities” and “you cannot be healthy without oral health.”  While the report was aimed at humans, the same holds just as true for our pets. Bacteria from inflamed, infected gums don’t stay in the mouth; they enter the blood stream and travel throughout the body.  Caught in time, this infection is treatable, but over time, potentially irreversible damage can occur to your pet’s vital organs.  Evidence is mounting about the association between infection and inflammation in the mouth and diabetes mellitus, heart disease, and chronic kidney disease.  Since these three diseases are common in pets as they age, it makes sense to take care of the mouth as best we can.  

Last week, Dr. Mike extracted nine teeth from an older cat.  

We call clients the night of the procedure to answer questions and address concerns they may have; when our technician followed up with this cat’s owner, the owner was thrilled.  After a long day of anesthesia and oral surgery, the cat had arrived home, ate an entire can of food, and was resting comfortably.  When I called her the next day, she said “I have a kitten again!”  The cat was more playful than the owner had seen in years.  I love hearing these stories!  It’s exactly why I care about teeth and disease in the mouth.  By improving the health of the mouth, we can dramatically improve our patient’s quality of life. Behavioral changes caused by dental pain often go unnoticed because of the gradual onset of dental disease. Once we eliminate the dental pain, the changes can be very dramatic!

Stay tuned and next week we’ll talk about dental disease and prevention!