Chemotherapy

Chemotherapy used at Veterinary Cancer Care

Chemotherapy is administered either intravenously, orally or locally (intralesionally). The intralesional treatment is part of an on-going clinical trial at VCC. The clinical trial uses intralesional chemotherapy mixed with sesame oil, which results in the release of a high dose of chemotherapy to the targeted area. As the body breaks down the sesame oil, the chemotherapy is released slowly, which treats the tumor without the side effects of intravenous chemotherapy. The result is similar to radiation therapy with reduced damage to healthy tissue.

Local treatment also has the advantage of being effective in treating micro-metastatic disease—when the cancer is in the early stages of spreading. Local side effects if and when they do occur, are reversible with basic care.

Injectable chemotherapy

Injectable chemotherapy agents may be given intravenously (IV), subcutaneously (SQ, under the skin), intramuscularly (IM) or intralesionally (IL, into the tumor, the region of the tumor, or the surgical site of tumor excision). Veterinary Cancer Care has an ongoing clinical trial using IL chemotherapy in place of radiation therapy.

L-Asparaginase is an enzyme derived from the bacteria E. coli. It is given SQ or IM. It may cause an immediate allergic reaction and/or pancreatitis.

Bleomycin is an antibiotic obtained from bacteria. It is given SQ or IL. It can cause an immediate fever or allergic reaction. Delayed symptoms are rashes, pneumonitis (inflammation of the lungs) and pulmonary fibrosis (scarring of the lungs) .

Carboplatin is a derivative of platinum, which is a transitional metal. It may be given to cats. It is given IV or IL, and may cause severe bone marrow suppression.

Cisplatin is a derivative of platinum, which is a transitional metal. It is not given to cats. It is given IV or IL, and may cause nephrotoxicity (toxic to kidneys).

Cytarabine was originally derived from the sponge Cryptothathya crypta, today it is synthetically made. Cytarabine can be gived as an IV and SQ injection.

Dacarbazine is a chemical developed to kill cancer cells. Dacarbazine is not used in cats. It is given as an IV injection.

Doxorubicin is an antibiotic. It is given in a slow, IV drip. The red dye may appear in your pet’s urine for a few days after treatment, which is normal and harmless. It can cause an allergic reaction. Because it is a vesicant, it can cause tissue necrosis if it gets outside the vein. It can cause heart toxicity in dogs and kidney toxicity in cats.

Fluorouracil (5-FU) is a synthesized anti-neoplastic drug. It is not given to cats. It is given as an IV or IL injection, and can cause neurotoxicity.

Mustargen is a nitrogen mustard. It can be given to both dog and cats. It is given as an IV injection, and can cause bone marrow depression, vomiting, and ototoxicity (toxic to ears).

Vincristine comes from pink periwinkle Catharanthus roseus. It is given IV through a butterfly catheter. Because it is a vesicant, it can cause tissue necrosis if it gets outside the vein. Side effects are constipation and neurotoxicity.

Vinblastine also comes from pink periwinkle Catharanthus roseus. It is given IV through a butterfly catheter. Because it is a vesicant, it can cause tissue necrosis if it gets outside the vein. Side effects are constipation and neurotoxicity.

Oral chemotherapy

Chemotherapy drugs that are given at home should be given in the morning with food and may need to be given with another support medication. Tablets should never be split and capsules should never be opened.

Cyclophosphamide is an alkylating anti-tumor drug. Tablets are usually given daily for 3-5 days at a time and tablets should not be split in half. A possible side effect can be hemorrhagic anemia.

Chlorambucil is a nitrogen mustard derivative, and can cause bone marrow suppression.

Lomustine is an alkylating agent. Capsules are usually given every 2-3 weeks, and can cause corneal complications.

Melphalan tablets are usually given daily for 7-10 days, and can cause bone marrow suppression. Melphalan is light sensitive and must be stored in a dark bottle.

Potential side effects

Unlike people, pets have relatively few side effects. However, all side effects should be monitored closely and treated immediately.

Gastrointestinal

Nausea (symptoms can be eating grass or drooling)

Vomiting

Diarrhea

Anorexia (loss of appetite)

Colitis (blood or mucous in stool or straining to defecate)

Suppression of Bone Marrow

Neutropenia: lowered white blood cell count. May lead to sepsis, a life threatening infection of the blood stream.

Anemia: lowered red blood cell count

May cause lethargy.

Thrombocytopenia: lowered platelet count. This affects the clotting process, so your pet may bruise or bleed more readily.

Alopecia (loss of hair)

Rare side effect in breeds with continuously growing hair. The hair should grow back when chemotherapy has stopped.

Side effects can occur immediately or days after treatment. With supportive care, side effects should resolve immediately. If side effects are not addressed, they can be fatal.

If your pet has side effects:

Do not wait! Be seen by us, your primary veterinarian, or an emergency clinic. A CBC (complete blood count) will be run to determine your pet’s white blood cell count.

Fever: This is an emergency and your pet needs immediate treatment. Standard treatment is obtaining a CBC, hospitalization, IV fluids, IV antibiotics and other supportive care. Neupogen, a drug that can stimulate the bone marrow to make more white blood cells, may be given.

Diarrhea: If mild and lasts less than 24 hours; give small frequent meals of a bland diet such as boiled chicken and rice. If there is scant blood and mucous in the stool (colitis), add fiber. Severe diarrhea lasts longer than 24 hours and is an emergency.

Vomiting: If mild and lasts less than 8 hours and has no other health problems such as kidney disease or diabetes; hold food and water for a few hours, then introduce water only, small amounts at a time for 12 hours. Then add small frequent feedings of a bland diet with a gradual increase in quantity. Severe or extended vomiting is an emergency.

Supporting your pet during chemotherapy

Most importantly, a pet undergoing treatment for cancer needs lots of extra love and attention. Often times, your pet will begin to look forward to their frequent visits to the veterinarian due to the extra attention and devotion they will receive from our staff.

Clinically speaking, many support medications are given along with chemotherapy to help normal cells and aid the body in processing chemotherapy drugs.

A CBC will be necessary during treatment. This will help monitor: white blood cells, which fight infection; red blood cells, which carry oxygen; and platelets, which are essential for blood clotting.

For more information about chemotherapy:

Please visit the United States National Library of Medicine/National Institute of Health’s website. Search their database for specific drug information.