Chemotherapy in Pets

The Two Scariest Words

Red tape with chemotherapy written on it

I heard it said once at a lecture by a veterinary oncologist that “cancer” was the scariest word in our language and that “chemotherapy” was the second scariest.  From many discussions over the years, I know that he was right. 

Technically speaking, the term “chemo” means simply chemicals or chemistry.  Taking an aspirin is “chemo”.  Cancer chemotherapy may involve many different drugs, in an endless mix of protocols, to treat an array of different cancers.  It is just too broad a term to consider by itself.   The details of diagnosis and drugs dictate what the experience may be like and what we can expect as an outcome.  Of course, there are also many individual variations in response and how different creatures handle the medications.  The potential benefits can be profound.  The potential side effects vary widely. 

We hope for ourselves, our families and pets to never hear either word and to never deal with a diagnosis of cancer.  The medical reality of course is that we do see cancer in pets and it is imperative that we know how to help these animals.  We have seen several cases of lymphoma, one of the most common cancers in dogs and cats, at our clinic in the past several weeks.  The diagnosis is devastating.  But, despite the aggressive nature of the disease, there is room for hope.  Chemotherapy can extend the quality and quantity of life significantly for most patients.  Toxicity and feeling sick on the chemotherapy drugs are a real concern and an important consideration.  But the vast majority of patients brave through therapy with few to no side effects.  A typical chemotherapy protocol for lymphoma involves 5 drugs used in 16 treatments given on a schedule over 24 weeks.  Two of the drugs are pills given at home and three of them require brief time at the clinic to administer.  Frequent blood tests are used to monitor patients.  We try to minimize the time animals are with us at the clinic.  

Ginger's last day of chemotherapy!  She is with part of the medical team who supported her, Maggie, Erika and Dr. Majeski.

Ginger's last day of chemotherapy!  She is with part of the medical team who supported her, Maggie, Erika and Dr. Majeski.

People commonly worry that their pet will feel sick for the whole time they are being treated.  We just would not tolerate that.  The animals can feel lethargic and even have some diarrhea or vomiting after some of the treatments but side effects are usually mild and transient.  Dogs and cats rarely lose hair.  If significant side effects occur, we may delay subsequent therapy or skip those specific medications when they come up again.  If necessary, we may even decide to forgo further chemotherapy.  Each successive treatment is an active choice based on the response to the preceding one.   It is a mantra of therapy, and cancer care in general, that we won't allow vomiting or diarrhea and we will alleviate pain.   Lymphoma is a disease we most often make a positive difference in the lives of our patients and owners.  There are many other cancers that we have effective treatments for as well.

I am also a strong advocate for complimentary medicine and alternative care.  My patients that receive acupuncture from veterinarians like Dr. Tweed or herbal medicine from Dr. Lena McCullough, along with chemotherapy, do the best.  In my experience, they have the longest survival, the fewest side effects and the best overall experience trying to combat their disease.  Visit her website,, for more information.

Should you ever face a cancer diagnosis for your pet, remember that there is hope and there are options.  I often say and truly believe that our pets have an enormous advantage over us.  They will never stop and ponder their diagnosis or prognosis.  They never look at the dog next to them and compare their good or bad fortune for the future.  They just take the next moment as it flows by and the tomorrows as they become known. 

May you never need any of this information.

Timothy R Kraabel, DVM, DABVP (Canine/Feline Practice)

President Elect, American Board of Veterinary Practitioners