What is chemotherapy?

“Chemotherapy in this context means the use of drugs that target and kill rapidly dividing cells, which, of course, cancer cells are,” said Monk.

By their nature, these drugs are “toxic,” but in this context it is a good thing as long as it is well-controlled, Monk said, because they are toxic to the cancer cells.

“Lymphoma is the most chemotherapy-responsive canine cancer that we treat,” she said.

The average patient is a middle-aged dog, but according to Monk, there are some breeds that appear to be “overrepresented,” or particularly susceptible: boxers, golden retrievers, Rottweilers, bulldogs and bull mastiffs.

The Wisconsin protocol

A number of treatment plans exist for lymphoma, but the Wisconsin protocol has one of the best remission rates. The 26-week regimen uses a combination of drugs, with 16 weeks of chemotherapy and 10 weeks of just blood tests, which keep track of levels, especially the white blood cell count.

The drugs used originally were developed for use in humans. Each has its own potentially serious side effects, which is part of the reason for close monitoring during and around treatment times.

? L-asparaginase (brand names: Elspar, Oncaspar and Erwinase). An enzyme produced by bacteria, it exploits the unusually high requirement that tumor cells have for the amino acid asparagine by destroying it outside the cell, thus depleting tumor cells of one of their main sources for growth.

? Vincristine (brand names: Oncovin and Vincasar). It is a member of the vinca alkaloid class of chemotherapy drugs and is extracted from the Vinca rosea plant. It targets abnormal cell division.

? Cyclophosphamide (brand name: Cytoxan). It is a nitrogen mustard derivative, meaning it is related to the toxic chemical weapon mustard gas used widely in World War I. It disrupts cellular DNA, especially those cells that are dividing rapidly.

? Doxorubicin (brand names: Adriamycin and Rubex). It works by impairing DNA synthesis, targeting rapidly dividing cells.

? Prednisone. A steroid designed to break down stored resources, such as fats, sugars and proteins. In chemotherapy, it is thought that Prednisone works by interfering with cell receptors that stimulate growth, thus preventing cell division.

The cost

The Veazie staff compiled estimates for Daisy’s weekly treatments, which varied between about $170 and $265, depending on the drugs and any necessary extras. The cheapest chemotherapy drug was less than $35. It would cost about $4,000 over six months, an amount my family could afford.

Other protocols are less expensive and less time-consuming. Remission times may be shorter, but “it’s not an all-or-nothing proposition,” said Monk.

“Chemotherapy is the right choice for some people and their pets,” she said, “and it’s not for others. Sometimes there are time or financial constraints, or the dog is terrified of the clinic, though that’s rare. We try to make their visits all about fawning over them and giving them treats.

“Even if pet owners choose not to go forward with drug therapy or surgery or whatever is the ‘best’ choice, there are often other things that can be done to help, whether it’s nutritional support, pain control or just to know what to watch for to help owners know when they may want to consider euthanasia.”

The providers

A telephone survey of more than a dozen veterinary clinics in the Bangor area showed that the majority don’t offer chemotherapy treatments for canine lymphoma.

Most clinics refer their lymphoma patients to Portland Veterinary Specialists, Bath-Brunswick Veterinary Associates or Boston-based clinics. These providers offer board-certified veterinarians, which means those doctors have undergone extra schooling and training and met the requirements established by that specialty board.

Bangor-area clinics that treat lymphoma with chemotherapy include Broadway Veterinary Clinic in Bangor and River Road Veterinary Hospital in Orrington.

Lucerne Veterinary Hospital in Dedham, where Stephanie Monk will be practicing, opened this week and will offer chemotherapy for canine lymphoma.

At the Veazie Veterinary Clinic, where Daisy was treated for her 26 weeks, Dr. David Cloutier said that each case would be decided depending on the individual.

Veazie may treat cases there, may offer a referral to former co-worker Monk at Lucerne Veterinary Hospital or may refer an owner to board-certified veterinary oncologist Gail Mason at Portland Veterinary Specialists.

“The important thing is to do what’s right for the patient,” he said.