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Things to keep in mind about chemotherapy: - In most cases,
you can stop treatment even after it’s started if it is not working or you change your mind.
- Chemotherapy is expensive, but you pay for each treatment,
not in one lump sum, and some veterinarians offer payment programs such as Care Credit to further reduce the financial hardship. If you have pet insurance, that will also reimburse you for some of the costs
of treatment.
- Dogs receive a much lower dose of chemotherapy drugs,
so they tolerate it much better than humans and often have few side effects.
- Earlier
treatment often results in better outcomes.
- While chemotherapy is often
a very effective form of treatment, it is not the ONLY treatment. Be sure to find out about all treatment options for
your dog.
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What are typical side effects of chemotherapy? Although each dog will vary in their ability to handle chemotherapy, most dogs will
exhibit some side effects at one point or another during treatment. Reactions normally do not occur right after treatment
though – side effects usually appear 2-3 days after the treatment. Your dog will probably seem a bit more tired
than usual, and may not have his or her typical stamina at various points during treatment, but often this is very short lived.
Also, most dogs will experience at least one bout with diarrhea at some point during treatment. In fact, you may
want to ask your veterinarian to give you a prescription for Metronidazole (Flagyl) at the
beginning of chemotherapy treatments as a safeguard, since this is a VERY effective drug for getting diarrhea under
control. If your dog does experience this side effect at some point, you will be glad to have it on hand.
Below is a description of some of the typical side effects of the chemotherapy drugs most commonly used, as described
in the Textbook of Veterinary Internal Medicine (2005). You can also learn more about other chemo drugs HERE.
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.
Will my dog lose their hair from chemotherapy?
In people, hair grows continually throughout their lives and since chemotherapy drugs usually target rapidly dividing cells,
hair loss is common in people undergoing chemo. But in most dogs, the bulk of their fur is not continually growing,
so the vast majority of breeds are not affected significantly by this side effect. Exceptions to this are the few
breeds that do have continual hair growth such as Poodles and Old English Sheepdogs. So, while you may notice some thinning
of your dog's coat, loss of whiskers, and possibly a change in the texture of your dog's coat, it is unlikely that
they will lose much, if any, of their fur.
What do I do if my dog has diarrhea after a treatment? One of the most helpful drugs
to keep on hand is Metronidazole (Flagyl). This drug can be very helpful if your
dog experiences severe diarrhea during treatment (which is not that uncommon), and is given in pill form. A
daily dose of Pepcid can also be very helpful in preventing stomach upset, and many pet owners choose to incorporate this
into their daily routine. For those who prefer a natural solution, giving your dog a tablespoon or so of
canned pumpkin (100% pumpkin, NOT pie filling), can help mild cases of diarrhea.
If your dog does experience severe diarrhea,
make sure they continue to drink enough fluids (you may want to put some chicken broth in their water to get them to drink
more), and consider giving them a blander, easier-to-digest diet for a couple of days, such as baby food or rice and boiled
chicken.
What’s a rescue protocol? A
rescue protocol is just a name for using a different combination of chemotherapy drugs when and if your dog stops responding
to the first protocol used. Since cancer cells tend to adapt and become resistant to certain drugs after
a while, a new combination of drugs can often help your dog get back into remission. An example of
a commonly used rescue drug is CCNU or lomustine.
How much will chemotherapy cost? Cost
will vary according to the size of your dog (the bigger the dog, the more drugs that need to be administered), the type of
cancer they have, the number of extra tests that need to be conducted and your particular vet’s fee schedule.
But, generally speaking, you should be prepared to spend several thousand dollars in the course of your dog’s
treatment, especially if you go through chemotherapy. But, as you pay per appointment, not in a lump sum,
this amount is spread out over several months. Also, if you have pet insurance, they will likely reimburse
you for some of the costs of treatment.
Why do I need
to monitor my dog’s temperature during chemo treatment? You
should consider investing in an in-the-ear pet thermometer (unless you’re proficient at taking a rectal temperature),
as it’s important to monitor your dog for fever throughout treatment. Because chemotherapy drugs often affect
the bone marrow and reduce the body’s ability to produce new blood cells, including the white blood cells responsible
for fighting infection, it’s very important to identify and treat any infections that might occur as early as possible,
as this is potentially the most serious side effect of chemotherapy. A fever is a indication that your dog could
have an infection of some kind. Your dog’s white blood cell count will generally be at its lowest 5-7 days after
treatment, and this is when they are most susceptible to developing an infection. If your dog develops a temperature,
call your vet immediately. This is an emergency!
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