Chlorambucil Side Effects in Cats

Chlorambucil (Leukeran) helps treat non-cancerous immune-mediated diseases. Chlorambucil targets cell division, alters protein production and causes cell death. Veterinarians prescribe Chlorambucil in chemotherapy protocols such as multiple myeloma, lymphocytic leukemia or ovarian cancer. Cats with immune-mediated conditions such as inflammatory bowel disease or immune-mediated haemolytic anemia may also benefit. Side effects relate to blood production, gastrointestinal upsets, nervous dysfunctions and alopecia, or slow re-growth of shaved hair.

  1. Myelosuppression

    • Chlorambucil may cause bone marrow suppression, or myelosuppression, as a side effect. The bone marrow, which lines the cavity of bones with a soft material, produces red and white blood cells and platelets. Myelosuppression refers to decreased blood cell production that can lead to a low blood count.

      Suppressing this source may result in anemia and/or a decrease in white cells. During the second week of therapy, this side effect may appear. Interactions with other drugs may compound bone marrow suppression and contribute other side effects such as infection.

      An overdose of Chlorambucil may cause bone marrow suppression in all cell lines. Pancytopenia refers to simultaneous blood-related deficiencies. In rare cases, pancytopenia, seizures, or infertility may result.

    Thrombocytopenia

    • Cats with pre-existing bone marrow depression or infection may develop thrombocytopenia, an abnormally low concentration of platelets in the blood. If the lining of the blood vessels suffers injury, the platelets would normally promote blood clotting or coagulation. If the cat has low blood platelet concentrations, the risk for spontaneous bleeding increases.

    Leukopenia

    • Chlorambucil may produce leukopenia or leukocytopenia as a side effect, especially in cats with pre-existing bone marrow depression. The cat would experience a decrease in white blood cell circulation, ranging between 50 and 3,000 cells per microliter. Because white cells fight infection, a decrease in white cells may lead to an increased risk for infection.

    Gastrointestinal

    • Cats may suffer from gastrointestinal side effects such as diarrhea, vomiting, stomach emptying or anorexia nervosa.

    Myoclonus

    • Chlorambucil may induce myoclonus, a rare nervous dysfunction, as a side effect. A cat's muscle, a portion or entire or groups of muscles contract involuntarily with rates up to 60 times per minute.