Side Effects of CeeNu Chemotherapy on Canines

Veterinary oncologists prescribe lomustine--trade name CeeNU--for the chemical treatment of lymphosarcoma and mast cell tumors in dogs. Approved by the United States Drug Administration for the treatment of brain tumors in humans, veterinarians legally use lomustine as an "extra-label" drug, reports Dr. Dawn Ruben of PetPlace.com. Lomustine destroys rapidly multiplying cancer cells by bonding with the cells' DNA but also influences other cells in the dog's body, resulting in side effects that can be dangerous.

  1. Myelosuppression

    • Veterinarians consider lomustine a myelosuppressive--the medical term for a drug that inhibits the activity of a dog's bone marrow. Since the bone marrow produces your pet's blood cells, this results in a decreased production of red blood cells that can lead to anemia. A lowered white blood cell count can predispose your pet to infections and a reduced number of platelets causes an increased risk of bruising and bleeding. According to veterinarians at Massachusetts Veterinary Referral Hospital, veterinary oncologists should run a complete blood count on their canine patients prior to beginning chemotherapy and again seven to 10 days following treatment when blood counts are typically at their lowest.

    Organ Toxicity

    • Liver disease related to lomustine use first shows during blood tests about 10 weeks into chemotherapy treatment, advise veterinarians at Mar Vista Animal Medical Center. Long before the dog develops symptoms such as vomiting, an inability to eat, blood in the urine and/or feces and jaundice--a yellowish coloring to the mucous membranes--approximately 70 to 80 percent of the liver becomes damaged. Oncologists typically monitor the patient's enzyme levels during treatment to determine the amount of damage produced and may discontinue administration of the drug.

    Gastrointestinal Disturbance

    • Lomustine may affect the gastrointestinal systems of some dogs but severe toxicity is relatively rare, according to veterinarians of the University of Georgia College of Veterinary Medicine Oncology Service. Your dog may experience incidences of vomiting, diarrhea, loss of appetite and lethargy. If your pet's symptoms persist for more than 24 hours, the veterinarians urge that you consult your veterinary oncologist immediately.

    Treatment Protocol

    • Available in 10 mg, 40 mg and 100 mg capsules, oncologists administer lomustine orally to canine patients every 21 days, reports Dr. Ruben. Veterinarians weigh and measure your dog's body then calculate the medical dose at a rate of 50 to 90 mg per square meter of your dog's body surface area.