The Oncologist’s Perspective on Chemotherapy and Gastrointestinal (GI) side effects: Part Two

In my last blog post, I told you that most vomiting and diarrhea associated with chemotherapy was mild and could be managed at home. Unfortunately, there are exceptions.

Typically if your dog is vomiting, you will be instructed to hold on food and water to rest the GI tract for 12 to 24 hours.  But if your dog vomits multiple times (more than five) in a few hours, he is likely dehydrated, and this will only worsen during the period that we are withholding water by mouth.  He also likely won’t respond to oral anti-vomiting medications at home if he is puking them back up, so hospitalization is typically required.

With IV fluids, we can quickly and effectively fix the dehydration while we rest the GI tract – no food and water allowed. In addition, we can give anti-vomiting medications and antibiotics in an injectable form, so we don’t upset the GI tract further with the oral forms of medications.

Hospitalization is always a bitter pill to swallow. I typically tell pet Guardians that the chance your pet will be hospitalized with serious side effects is less than 5%. But once they are getting admitted, it is 100% for your pet. And I know you don’t want to leave your pet. I would also prefer every moment to be spent at home. But there are a few things to remember:

• Chemotherapy side effects are temporary. With early intervention and comprehensive supportive care, the GI tract will heal and your dog will feel better soon, often within a day or two. I plead with you to NOT euthanize your pet now. If you have decided to treat with chemotherapy, support them through the hospitalization and then decide what to do. It is remarkable even to me what a difference a day make with IV fluids and supportive care.
• Secondly, if your pet does get sick, chemotherapy can be continued. Yes, the same drug can be given, with adjustments.  The dose will be decreased and preventative medications like antibiotics, anti-vomiting, and anti-diarrhea medications to prevent another serious complication will be used. Repeat complications are highly unlikely in my patients. That’s why your dog should be under the care of an oncologist that manages a high number of chemotherapy patients and has expertise with the drugs and their side effects.

Charlie is an awesome Golden Retriever I am treating with the UW (University of Wisconsin) protocol for lymphoma. Earlier this spring, Charlie had multiple episodes of vomiting and diarrhea in the days following his first dose of vincristine.  When he came in on emergency at my hospital the Animal Specialty Center, he was too weak to stand and quite dehydrated. He had a fever and his white blood cell count was low. Charlie was admitted and spent two days under my care on aggressive IV fluids, antibiotics, anti-vomiting, and anti-diarrhea medications.  Within a day his white blood cell count was rebounding, and Charlie recovered.  We delayed his next treatment a few days, but the good news was his lymphoma was responding.

As you would expect, Charlie’s mom was quite concerned about giving Charlie vincristine again. Dogs get 8 doses of vincristine in the protocol. I told her repeat complications are uncommon, but she was obviously nervous. Well Charlie received all subsequent 7 doses, at a reduced dose and with preventative meds, and never had another complication from vincristine.

I am happy to report Charlie completed his protocol last month and was doing great at his one month follow up recheck last week. I cannot wait to see them both next month. Mom could not believe he did not have another major complication. That is my job: as Charlie’s oncologist, I adjusted his treatments so he could successfully tolerate them. I always say the goal is for my patients to not only live longer, but live well. And Charlie is doing just that.

To learn more about GI side effects and ways to manage them, including full spectrum approaches, check out the Dog Cancer Survival Guide.