When Treating Pet's Cancer, How Much is Too Much?

Published Jul. 15, 2015

I regularly face owners who decide not to pursue therapy for pets that have what are considered treatable cancers. The reasons for this choice can stem from concerns for too many vet visits, too much strain for the pet to go through, projection of their own feelings about cancer treatments on their pets, or financial limitations.

Over the course of my career, it hasn’t become any easier to be on the receiving end of those appointments. I want to help all pets with cancer and I want all animals to be afforded the opportunity to undergo the ideal plan to afford them the best chance of survival. Logically, I know this isn’t a realistic expectation. But it’s an accepted part of my job, and it forces me to remain open-minded about my professional goals.

Consider the opposite scenario. Those owners who want to do everything for pets that have been diagnosed with a form of cancer that has no known beneficial therapeutic option, or where we’ve run out of choices with any realistic expectation of helping them fight their disease. Those cases create a different sense of anxiety for my soul.

Practically, this translates into a scenario where the “frontline” therapy fails to keep a patient cancer-free, yet they remain relatively asymptomatic for their condition. I need to be prepared with a back up plan. In those cases, most owners want to know what else can be done to help maintain their pets' quality of life.

My goal as a veterinarian is to make all decisions about my patient’s care using evidence-based information. I want to be sure the recommendations I present are medically sound and proven to be of a benefit.

Unfortunately, evidence based information is severely lacking in veterinary oncology and a startling amount of choices are made using simple inferences, experience, and logic.

The good news is that the more common cancers (e.g., lymphoma, osteosarcoma, mast cell tumors) do actually have fairly specific preliminary treatment algorithms. Different oncologists will offer subtle variations on the same theme, but for the most part we agree on the same initial plan of attack.

What many owners find confusing is that once we’ve moved past the primary recommendation, there are usually no universally agreed upon “next best” options amongst our oncology community. Just because I possess solid research-based information about how to treat one disease at the onset does not mean there’s enough evidence to support what the next best plan of action could be. The same is true for those cancers with no accepted initial standard of care. For those cases, we just face the confusion a bit earlier on in the plan.

Using an example of a dog with lymphoma, oncologists typically endorse a multi-drug injectable chemotherapy protocol that lasts about 6 months in duration. This plan offers the average patient about 1 – 2 years of survival. Many owners are willing to pursue this plan because of the low chance of side effects and the ability to maintain an excellent quality of life well beyond the treatment period.

However, despite being considered our most valuable and effective protocol, 95% percent of dogs with lymphoma are not cured with this plan. Therefore, more often than not, I need to be prepared to offer owners “something else” to help their pet when the cancer resurfaces.

There are numerous “rescue” protocols for such cases. In actuality, few owners are willing to try such second and third line protocols for their dogs with cancer. Many times they perceive the disease relapse as the real indicator that their pet truly has a fatal disease. Other times, a myriad of emotional, physical, financial, and ethical considerations factor in to the decision making process.

The most difficult scenario occurs when pets are asymptomatic for their disease and I have no suitable options to help them battle their disease. It may seem counterintuitive to feel frustrated at not being able to make an animal that already feels good any different, but it’s a core part of my work.

I want to be able to keep trying to help pets with cancer, not only for their owner’s sake, but also for their own happiness and well being. Even when a diagnosis of a cancer known to be 100% fatal is on the table, if the animal feels good, and the owners are happy with it’s quality of life, then I am always willing to try to come up with an alternative plan.

Sometimes it’s because I want to be able to give owners some form of hope. Other times it’s because I want to try a new therapy or idea and see if it can help. Mostly it’s because I want to be able to kick a patient’s cancer down as much as possible.

I can appreciate how owners might read my honesty as lack of experience, or “hedging” on telling them how we should proceed. Most people I meet prefer the simpler approach to treating their pets' cancer. They want me to make a recommendation they can agree, or not agree, to follow.

The most important point I can make in any of these scenarios is that “just because we can, doesn’t mean we should.” This is the phrase I tell all owners when making such difficult choices about their pet’s cancer care.

It’s how I remind everyone involved in the decision making process to keep the right perspective and to make sure we truly first do no harm.