FAQ's: Common Chemotherapy Drugs

What are the most common chemotherapy drugs used and their side effects? 

Below is a description of some of the most common chemotherapy drugs used and their typical side effects, as described in the Textbook of Veterinary Internal Medicine (2005).  You can also learn more about other chemo drugs

Prednisone Side Effects:

Although Prednisone is not officially a chemotherapy drug, and is frequently used to treat a variety of conditions, it is commonly used as part of a chemotherapy protocol, which is why it is included here.

  • Increased thirst - drinking large amounts of water
  • Increased need to urinate (from drinking so much water!)
  • Significantly increased appetite
  • Panting
  • Can cause some mild behavior changes
  • More prone to overheating/exertion during exercise

In some cases in which pet guardians could not afford the cost of chemotherapy, Prednisone has been used alone to treat Lymphoma.  Although it is generally a short-term fix, it can buy some extra time with your pup if no other options exist.

Elspar (L-asparaginase) Side Effects:

Can cause an allergic reaction.  As a result, Diphenhydramine (Benedryl) is usually given to the dog before this drug is administered.  Any reaction to this drug would normally occur within 15-20 minutes of administration.  As a result, you may be asked to wait with your dog in the lobby for a few minutes after administration to ensure that no side effects occur.

Vincristine Side Effects:

This drug was consistently the most difficult one for Georgia to tolerate, although for many, it is not a problem.  Side effects can include:

  • Diarrhea
  • Loss of Appetite
  • Low white blood cell count (WBC)
  • Tremors (usually a signal to me that her WBC count had dropped very low)
  • Tissue damage at injection site

If this drug leaks outside the vein, it will begin to kill skin tissue.  After one treatment, Georgia developed blackened skin that later became flaky and red.  It ultimately remained a grey, hairless patch on her leg and was thereafter more prone to sunburn, but didn’t bother her.

Cytoxan (Cyclophosphamide) Side Effects:

  • Low white blood cell count (usually occurs 5-7 days after administration)
  • Can be toxic to the bladder and cause bloody urine or chronic cystitis, so often lasix or a diruetic is  given along with this drug to ensure that your dog expels this drug from their bladder regularly.

We generally preferred to give Georgia a special treat of “tuna water” - the water from a can of tuna mixed with plenty of fresh water in her bowl, which she would always drink until it was gone.  I always made sure to take Georgia out at least once during the night on the day that she received this drug, to be sure that the drug wasn’t staying in her bladder overnight.  Dandelion (found at any health food store in capsule form) is also a well known and safe duretic herb and can be used instead of conventional drugs.

Adriamycin (doxorubicin) Side Effects:

This drug has a cumulative effect on the heart.  If your dog receives too much of this drug over the course of treatment, they could develop heart problem.  As a result, only so much of this drug can be given to your dog in their lifetime.  The vet should monitor your dog’s heart throughout treatment to ensure that it is not causing any problems, and if your dog has any existing heart conditions, you may want to consider an alternate drug, such as Mitoxantrone.  In some cases, you may want to consider having an x-ray or ultrasound done prior to each Adriamycin treatment to confirm that there is no heart damage present.  Using a CoQ10 supplement may help reduce the cardiotoxicity of this drug.

  • Nausea or Vomiting
  • Diarrhea (usually occurs 2-5 days after administration)
  • Loss of appetite

This drug is often the one that causes the most side effects for dogs, although Georgia was not bothered by the Doxorubicin.

This website is not intended to replace the advice of a veterinary professional, and is for informational purposes only.   Please seek the advice of your veterinarian or a veterinary specialist before giving your dog any supplements or pursuing any alternative cancer therapies. 

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