What Is Chemotherapy?
Chemotherapy is the treatment of cancer with drugs that can destroy cancer cells. These drugs often are called "anticancer" drugs.
How Does Chemotherapy Work?
Normal cells grow and die in a controlled way. When cancer occurs, cells in the body that are not normal keep dividing and forming more cells without control. Anticancer drugs destroy cancer cells by stopping them from growing or multiplying. Healthy cells can also be harmed, especially those that divide quickly. Harm to healthy cells is what causes side effects. These cells usually repair themselves after chemotherapy.
Because some drugs work better together than alone, two or more drugs are often given at the same time. This is called combination chemotherapy.
What Can Chemotherapy Do?
Depending on the type of cancer and how advanced it is, chemotherapy can be used for different goals:
To cure the cancer. Cancer is considered cured when the patient remains free of evidence of cancer cells.
To control the cancer. This is done by keeping the cancer from spreading; slowing the cancer's growth; and killing cancer cells that may have spread to other parts of the body from the original tumor.
To relieve symptoms that the cancer may cause. Relieving symptoms such as pain can help patients live more comfortably.
Is Chemotherapy Used With Other Treatments?
Sometimes chemotherapy is the only treatment a patient receives. For other types of cancer chemotherapy may be used in addition to surgery and/or radiation therapy.
Which Drugs Are Given?
Some chemotherapy drugs are used for many different types of cancer, while others might be used for just one or two types of cancer. Your veterinarian recommends a treatment plan based on:
• The type of cancer your dog has.
• The part of the body the cancer is found.
• The effect of cancer on the dogs normal body functions.
• The dogs general health.
Please see list of the common chemotherapy drugs given to dogs at the bottom of the page.
Will Chemotherapy Make My Dog Sick?
Canine Lymphoma: Protocols For 2004
Gregory K. Ogilvie, DVM, DACVIM (Internal Medicine, Oncology)
Many dogs experience some form of stomach or intestinal discomfort two to seven days after a chemotherapy treatment. Your veterinarian will prescribe medication to try to prevent or treat the discomfort. Below are listed some steps you can take at home.
Upset stomach (Nausea)
1. If your dog begins to show any signs of upset stomach (drooling, 'smacking' lips) or loss of appetite, administer the medicine your doctor prescribed for nausea.
2. Offer ice cubes every few hours.
3. After 12 hours, feed your dog small, frequent meals instead of one large meal.
4. Call your veterinarian if you have concerns, or if the condition persists for more than 24 hours.
1. Do not give your dog any food or water for 12 hours.
2. After 12 hours, offer your dog ice cubes, then water, then small bland meals.
3. Call your veterinarian if you have concerns, or if the condition persists for more than 24 hours.
Loss of appetite
1. If your dog or cat begins to show any signs of upset stomach or loss of appetite, administer the medicine your doctor prescribed for nausea.
2. Offer your dog or cat four small meals a day.
3. Add warm broth, animal fats, and favorite foods to increase flavor and appeal.
1. If your dog or cat begins to show signs of diarrhea, administer the medicine your doctor
prescribed for diarrhea.
2. Keep water available at all times.
3. If your dog or cat is also not eating, offer chicken or beef broth.
4. Give Pepto Bismol® (dogs only), 1 tablespoon per 10 pounds of body weight every 4 to 6 hours.
5. Call your veterinarian if you have concerns, or if the condition persists for more than 24 hours.
Reduction in the Number of White Blood Cells (Neutropenia)
There are various types of cells in the blood. The decrease in the number of infection fighting white blood cells is known as neutropenia. Many chemotherapeutic agents impair the bone marrow's ability to produce cells. As a result, neutropenia may occur seven to ten days after chemotherapy. Neutropenia, alone, is not a danger to your dog. However, your dog to fight off infection is impaired by neutropenia. Your dog is
given a complete physical, and a blood test called a complete blood count (CBC) is performed prior to each drug treatment. Should your dog have a significant reduction in the number of white blood cells, your veterinarian may wish to perform periodic blood tests, and/or prescribe antibiotics to protect your dog from infection.
If Adriamycin®, is accidentally given outside the vein, severe tissue reactions can result. Therefore, drugs like Adriamycin is handled with the utmost care, and is only administered by highly trained professionals. If irritation of the injection site develops in the form of pain or redness, apply ice packs for 15 minutes every three hours. Call your veterinarian if you have concerns, and certainly if the condition persists for more
than 24 hours.
Allergic reaction to chemotherapeutic agents is rare, and not a problem you will have to treat at home. Should your dog or cat have an allergic reaction to any drug, it would develop upon administration, and
your veterinarian and the hospital staff are trained to treat patients for allergic reaction.
Adriamycin®, in some rare cases, can irreversibly damage the heart muscle. The dose of Adriamycin® prescribed for your dog is below the dose that usually causes heart disease. Less than 10% of our patients develop heart disease as a result of Adriamycin® chemotherapy. Your veterinarian will discontinue the use of Adriamycin® if heart disease is detected at any time.
Increased Drinking of Water, Urination and Appetite
Prednisone can cause increased drinking of water, urination, panting and enhanced appetite. This is usually mild and self limiting, but in some patients it can be quite marked.
Will Chemotherapy Make My Dog Lose His Hair (Alopecia)?
While whiskers are commonly lost, substantial hair loss is not generally experienced by dogs on chemotherapy. There are some exceptions and those are breeds that have synchronous hair follicle activity. Most breeds have hair that are in different stages of the growth-shed cycle at the same time, however a few breeds have all hairs in the same stage of growth-shed at the same time and these are the breeds that may have a baldness issue. They include the Olde English Sheepdog, Poodle, Maltese, Irish Wolfhound, Lhasa apso and Shih tzu. The hair will regrow after the chemotherapy and ended and often will come back in a different color or texture.
Chemotherapy Side Effects by Drug
Most people have an image of “the chemotherapy patient” either through experience or the media and this image typically includes lots of weakness, nausea, and hair loss. In fact, the animal experience in chemotherapy is not nearly as dramatic. After the pet has a treatment, one should expect 1-2 days of lethargy and nausea. This is often substantially palliated with medications like Zofran® (a strong antinauseal commonly used in chemotherapy patients). These side effects are worse if a combination of drugs is used but the pet is typically back to normal by the third day after treatment. Effectively, you are trading 8 days of sickness for 6-12 months of quality life.
Almost all chemotherapy drugs have the potential to cause serious side effects, fortunately, these side effects are relatively uncommon. Most pets tolerate chemotherapy very well, with minimal problems, however you need to be aware of the potential problems that can occur.
Nausea and vomiting – usually mild and self-limiting.
Diarrhea – 1-3 days of soft stools is fairly typical after Adriamycin chemotherapy, but if any fresh blood or blood with mucus is seen, please call. This can usually be controlled with medications.
Low white blood cell and/or platelet counts – when seen, occurs 7-10 days after treatment. This can cause decreased ability to fight infection and can possibly inhibit the blood’s ability to clot resulting in bleeding.
Loss of hair, darkening of skin – more common in certain breeds (curly coated breeds such as Poodles, Old English Sheepdogs).
Inflammation, pain, tissue damage if drug is injected outside of the vein.
Heart disease can be seen secondary to Adriamycin, however, in the normal heart, this only occurs after a maximum number of dosages have been exceeded. It is important that we know that your dog's heart is normal prior to the use of this drug. An echocardiogram may be necessary if underlying heart disease is suspected prior to using Adriamycin.
VINCRISTINE (Oncovin)/VINBLASTINE (Velban)
Constipation or diarrhea.
Inflammation, pain, tissue damage if drug is injected outside of the vein.
Muscle weakness (rare).
Low white blood cell and/or platelet count – usually only seen as a potential problem with vinblastine.
When seen, this occurs 7-10 days after the vinblastine treatment, and can result in decreased ability to fight infection and can possibly inhibit the blood’s ability to clot resulting in bleeding.
Nausea, vomiting, diarrhea, loss of appetite. If any of these occur, it is usually 2-5 days after treatment.
Low white blood cell counts – if seen, occurs 7-10 days after treatment, and can result in decreased ability to fight infection. Platelets are usually spared in the case of cytoxan.
Bladder irritation – encourage water intake and adequate exercise on the days you give cytoxan.
If you notice blood in the urine or straining to
urinate, please call your veterinarian.
Increased water drinking and resultant increased need to urinate.
Stomach irritation (much like aspirin can cause GI upset) – can cause vomiting, poor appetite, dark stools. Please call your veterinarian if any GI symptoms are noted.
Nausea and vomiting – usually only seen during administration of the drug or within first 24-48 hours, often controlled with medication.
Low white blood count and/or platelet count – typically not a problem with cisplatin, but can occur. Seen 7-10 days after and sometimes up to 16 days after treatment – resulting in decreased ability to fight infection, and possibly bleeding.
Kidney damage – the mechanism of this problem is not completely known, but we do know that "flushing" the kidneys (diuresing with large volumes of fluids) prior to and during the administration of the drug usually prevents kidney damage.
Increased frequency of urination – generally only lasts for several days following treatment and is due to the high volumes of fluids used during treatment.
Nausea, vomiting, diarrhea, loss of appetite – relatively uncommon, but can occur 2-5 days after treatment.
Low white blood cell and/or platelet counts – highest risk at 7-10 days after treatment.
Kidney damage DOES NOT appear to be a problem with carboplatin (as it is with cis-platin, it’s close relative).
Nausea, vomiting, loss of appetite can occur, but are extremely uncommon with Mitoxantrone.
Low white blood cell and /or platelet counts – highest risk at 7-10 days after treatment.
Nausea, vomiting, diarrhea, loss of appetite – can be quite severe in some patients. If these symptoms occur, please discontinue the drug and call your veterinarian.
Low white blood cell and/or platelet counts – can result in decreased ability to fight infection and possible secondary bleeding.
Nausea and vomiting, usually mild and self limiting.
Diarrhea – sometimes with fresh blood and mucous, can often be controlled with medication, so call your veterinarian.
Low white blood cell and/or platelet counts – highest risk 7-14 days after treatment.
Low white blood cell and/or platelet count – can occur at almost anytime during treatment, so patients on longer-term therapy must be periodically monitored. Drops in counts tend to be mild and take several weeks to several months to occur.
CYTOSINE ARABINOSIDE (Cytarabine)
Low white blood cell and/or platelet counts - highest risk 7-14 days after treatment. Degree of suppression of counts depends on route of administration. Longer IV infusions have greater risk of lowering blood counts; subcutaneous injections seem to have lower risk).
GI upset (nausea, vomiting) can occur, but tend to be rare.
Acute allergic reaction – usually seen within 30 minutes of administration of drug. Is usually prevented with administration of Benadrylâ (anti-histamine) prior to treatment.
Pancreatitis and resultant vomiting and diarrhea is possible, but uncommon.
Cannot be given if platelet counts are low prior to treatment as coagulation abnormalities could result.
Nausea and vomiting are infrequent.
Low white blood cell and/or platelet counts can occur, however, may not occur for weeks to months after being on the medication.
Primarily used for central nervous system cancers and resistant lymphomas.
Low white blood cell and/or platelet counts – can be marked, cumulative, and delayed (up to 6 weeks).
Nausea and vomiting – risk greatest 2-5 days after administration of the chemotherapy.
Significant liver toxicity has been noted, especially in patients with abnormal liver function.
If your dog is taking a drug that causes low blood counts and he/she starts feeling ill (lethargic, not eating, vomiting, and/or diarrhea) take his/her rectal temperature. Call your veterinarian IMMEDIATELY if the temperature is above 103.5° F.
If vomiting is frequent or persists longer than 24 hours, please call veterinarian.
If you are uncertain about the significance of any sign/symptom you are seeing, it is better to be safe and call us rather than waiting and watching to see if the symptom resolves.