Medical & Radiation Oncology

Side Effects 2018-07-03T02:53:53+00:00

Side Effects

side effecdts

Although smaller doses of chemotherapy are given to pets, that doesn’t mean that your pet will not have side effects from the treatment. Changes in appetite, diarrhea, lethargy, allergic reactions and other side effects are common. There are also many options to help lessen the side effects for your pet while he or she is under going treatment.

Loss of appetite

This is one of the more common side effects and may occur after a dose of any chemotherapeutic drug. Loss of appetite may last a day or two, which would probably be indicative of some nausea. Your pet may need to be prescribed an anti-nausea medication. If your pet experiences a loss of appetite, feed him or her frequent, small meals.

It’s preferable to keep your pet on normal food, but you may need to introduce some bland food to increase your pet’s interest in eating. Bland foods mean no high fat or heavily spiced food. Some good options included:

  • Boiled chicken or hamburger or canned chicken in water (not gravy). Mix the meat with some white rice or boiled potatoes.
  • Low fat yogurt or cottage cheese.
  • Cooked eggs. These can be easily prepared in the microwave, but do not use butter.
  • Canned food (if your pet normally eats kibble). Remember to use a bland or sensitive stomach formulation.
  • Baby food. Use products that are meat only and with no onion powder.
  • Cooked fish or canned fish (in water) can entice dogs and cats
  • If you need to encourage your pet to drink for some reason, adding a little low fat, low sodium broth to water can be helpful


Drugs_optIf your pet is vomiting, pick up all food and water. Do not allow access to either for six to eight hours. Sometimes people think this may dehydrate their pet, but actually, if a pet drinks water and then proceeds to vomit it will become more dehydrated than if he or she drank nothing. After six to eight hours, offer a small amount of water or ice. If your pet does not vomit, continue to offer small amounts of water at intervals.

After four to six hours, offer a small amount of bland food. Gradually mix in the normal diet over the next few days. If your pet continues to vomit after following the above instructions, please do not hesitate to call Veterinary Specialty Center. Your pet’s oncologist may prescribe an anti-nausea medication for your pet.

Chemotherapeutic drugs which are more likely to cause vomiting are Doxorubicin (Adriamycin), Cisplatin, Streptazatocin (Zanozar), Carboplatin, and Elspar (L-asparaginase)


Diarrhea is not as serious a concern as vomiting as long as your pet maintains adequate hydration and energy levels. Sometimes there may be small drops of red (fresh) blood in the stool, which is merely a sign of irritation of the bowel. Diarrhea sometimes takes several days to a week to resolve.

One at home remedy is adding white rice to your pet’s food to bulk up the stool. Also try to avoid any food or treats besides your pet’s normal food to minimize irritation. There are some medications that can be prescribed if the diarrhea is not resolving. Do not use human products like Kaopectate or Pepto-Bismol as these contain aspirin products. Do not use products like Imodium or Lomotil as these tend to stop intestinal motility.

Veterinary Specialty Center

Increased hunger, thirst and/or urination

Increased hunger, thirst and/or urination are not side effects of chemotherapeutic drugs, but are a side effect of some of the drugs used in conjunction with the chemotherapy treatment.

  • Prednisone – This is a steroid that is often used during the treatment of cancer and can cause increased urination (volume and frequency), hunger and thirst. Keep in mind that while your pet may seem extremely hungry from this medication, he/she does not need extra food. In fact, many pets tend to gain weight while on prednisone because their owners feel they need more food. Because prednisone causes your pet to form larger volumes of urine, please do not restrict his/her water intake as this may lead to dehydration. Also, do not let your pet gorge him/herself on water as this may cause vomiting
  • Lasix (furosemide) – This medication is a diuretic, which means that it will cause more urine to be produced and your pet will drink more. If your pet is on this drug, you must leave extra water and allow extra trips outside for your dog to urinate. Dogs will be sent home with Lasix if they have received Cytoxan (cyclophosphamide), which can potentially cause a sterile cystitis, or bladder infection. Lasix isn’t prescribed for cats, but they will be given fluids under their skin to flush their bladder. The increase in drinking and urination flushes the bladder and protects it from infection.


Veterinary Specialty CenterMild lethargy – the lack of energy – is a common side effect of chemotherapy. Approximately three to six days after your pet’s treatment, he or she may seem to sleep more or be less interested in play. This should not concern you and should resolve in a few days. However, if your pet seems very lethargic (i.e. will not get up to eat, drink, or relieve him/herself) contact your oncologist immediately.

Allergic reaction

Some chemotherapeutic drugs such as Elspar (L-asparaginase), Doxorubicin (Adriamycin), and Paclataxol can trigger an anaphylactic (allergic) reaction. To prevent, pets will be given an antihistamine, an anti-emetic (anti-nausea) and sometimes a steroid prior to administration of chemotherapy to minimize the risk.

Tissue sloughing

Some drugs must be delivered directly into the vein only because they can damage other types of tissues. These drugs are called vesicants. Some vesicants will cause minor irritation (Vincristine, Vinblastine, and Mitoxantrone). Adriamycin (Doxorubicin) and Doxil can cause very severe damage, which may require surgery to repair.

Great precaution is taken when giving these drugs, including placing an indwelling intravenous catheter and diluting the drug. All cats are sedated for adriamycin to prevent movement and a few dogs also require a mild sedative to discourage movement as well. If you ever notice redness or inflammation near the administration site please contact us immediately at (847) 459- 7535.

Change in urine color

Adriamycin (Doxorubicin) may cause the color of your pet’s urine to change to reddish-brown for a few days. This should not concern you.

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