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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Guidelines for Dealing with Your Dog’s Chemotherapy Side Effects

Updated: December 6th, 2018

chemo-side-effectsAs I’ve discussed in other posts, chemotherapy is very well tolerated in dogs.

Yes I know that is hard to believe. I have had family members get chemo and we have all seen it on TV, but happily it’s not like that for dogs.

Approximately 80% of dogs do not have side effects at all … and about 15-20% will have mild to moderate side effects.

Today we will discuss how you can help identify and manage GI related side effects after chemotherapy treatment.


How do I tell if my pet is nauseous? Nausea is often manifested by decreased appetite, drooling, or your pet approaching the food as if he or she is hungry … but then not actually eating. (Think about how the smell of food can make you nauseous when you are not feeling well.)

What do I do?

  • First, don’t feed your dog for now, but offer ice cubes every few hours.
  • Start anti-nausea medication as prescribed. I typically send my patients home with Cerenia® at the 1st chemo visit. But other options include metaclopromide (Reglan®), mirtazapine, or Zofran®.  I think you should have these on hand at home.
  • After 12 hours, feed very small but frequent meals (not one large meal).
  • Call your veterinarian if nausea persists for more than 24 hours.


Here’s what to do if your dog is vomiting.

  • No food and water for 12-24 hours.
  • If the vomiting is mild (one or two episodes), start the anti-vomiting/anti-nausea medication as prescribed (Cerenia®, metaclopromide (Reglan®), or Zofran®).
  • If there is no vomiting for 12-24 hours, offer small amounts of water or ice cubes.
  • If your pet does not vomit after drinking the water over the next 12-24 hours, offer small amounts of bland diet.
  • What is a bland diet? Bland diet options include boiled chicken, lean meat, or cottage cheese, with rice, or a commercially prepared bland diet, such as Eukanuba Low Residue, Hills I/D.
  • If there is still no vomiting, gradually reintroduce your pet’s normal diet, mixing it in to the bland diet
  • Severe vomiting can lead to dehydration. If the vomiting is severe, persists for more than 24 hours, or is accompanied with a fever of greater than 103°F, please bring your pet to your oncologist, family veterinarian, and an emergency clinic.

Get a copy of this informative seminar to learn more about Chemotherapy Side Effects


Here’s what to do if your dog is experiencing diarrhea.

  • Offer the bland diet (as above) and fresh water.  When you switch back to your pet’s regular diet, wean them back gradually.
  • If you were sent home with an anti-diarrheal medication (such as metronidazole (Flagyl®), sulfasalzine, or Tylan®), start the medication as prescribed. Again, I think you should have these on hand, along with a probiotic.
  • I also recommend a probiotic for dogs with diarrhea.

Can I use over the counter (OTC) meds for diarrhea??

  • For dogs, Pepto-Bismol can be given. Pepto-Bismol® is also known by its generic name bismuth subsalicylate. It is a human OTC medication for diarrhea and a GI tract protectant. The dose is 2 to 2.5 ml for every 10 lbs up to every 6 hours. Do not exceed therapy for more than 5 days. There are 5 ml in a teaspoon. Side effects are uncommon, and included vomiting and stool discoloration. Refrigeration may improve palatability. This will discolor the stool (may make it black). Do not give Pepto-Bismol® to cats.
  • Loperamide, also known as Imodium®, is an opiate anti-diarrheal that decreases gut motility.  It is a human OTC medication.  It should be discontinued if diarrhea continues 48 hours after starting the medication. Contact your veterinarian if your pet experiences constipation, depression, or slowed heart or breathing rates while being treated with loperamide. It should not be used in Collies and Collie-type breeds due to sensitivity. Rarely it may cause CNS depression. Only use after approval from your veterinarian, as there are certain conditions in which this can be harmful, including respiratory disease, severe kidney disease, hypothyroidism, and Addisions. The dog dose is 0.2 mg/pound by mouth every 8 to 12 hours. It typically comes a 2 mg capsules and liquid 0.2 mg/ml.   So a 45 lb dogs should receive approximately a 2 mg tablet every 8 to 12 hours. Use in cats is controversial as may cause excessive excitement.
  • If the diarrhea is severe, bloody, or black, persists for more than 48 hours, or is accompanied with a fever of greater than 103°F,  please bring your pet to your oncologist, family veterinarian, and an emergency clinic.

Live longer, Live well,

Dr. Sue

For more helpful information, get a copy of the Dog Cancer Survival Guide


Leave a Comment

  1. Debbie Downey on March 9, 2014 at 12:15 pm

    I have a giant schnauzer diagnosed 2 weeks ago with Lymphoma. She has had the first dose of Vincristine. She has multiple LN involvement but there appears to be no spread to organs. She had no symptoms except for swollen nodes. The SM node was the side of a walnut when we had the first chemo dose. On day 4 the SM node was pecan sized on day 6 slightly smaller than almond size. Is this a normal response to therapy. No side effect…. I would like to think that this is a good sign that she is responding well???

  2. Mary Straus on March 5, 2014 at 2:31 pm

    I’m confused by something you wrote about Loperamide:

    “The dog dose is 0.2 mg/pound by mouth every 8 to 12 hours. It typically
    comes a 2 mg capsules and liquid 0.2 mg/ml. So a 45 lb dogs should
    receive approximately a 2 mg tablet every 8 to 12 hours.”

    At 0.2 mg/pound, the dosage for a 45-lb dog would be 9 mg, not 2 mg. Could you clarify?

  3. john on March 4, 2014 at 8:10 am

    my dog has had 2 treatments for anal sac carcinoma with carboplatin. her second, last dec. 2013, resulted in a severe reaction from which my dog almost died. in fact, my dogs primary vet and her oncologist expected my dog to die. she’s recovered. her white cells and t-cells were dangerously low for sometime. her platelets are in the low range of normal and may never come fully back to what thye were. in hindsight i would have gotten a second opinion regarding the carboplatin; and, knowing what i know now i at least would have asked the vet to start with low doses to see how my dog would react.

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