Feline Side Effects of Vincristine

Vincristine, a potent cancer fighting drug, comes from the vinca plant, commonly known as periwinkle. Vincristine treats tumors and cancers as well as other diseases. It is also distributed under the brand names of Oncovin and Vincasar PFS. The medication prevents cancer cells from dividing, which kills the cell. Vincristine is only available by prescription and used under the careful supervision of a licensed veterinarian because of its strength and potency as well as the side effects it can have on cats. You should discuss any side effects you believe are caused by this medication with your vet.

  1. Digestive

    • Watch cats receiving vincristine closely for gastrointestinal toxicity. The medication causes the intestines to work poorly, which can cause diarrhea, constipation and vomiting. These symptoms will normally occur anywhere from three to five days after receiving the drug. Blood may appear in the urine or stool of the cat receiving therapy. Pet owners should also watch for dehydration caused by these symptoms.

    Hair Loss

    • As with many cancer treatments, the largest side effect of using vincristine is hair loss. Since the drug kills cancer cells and keeps them from dividing, it also kills other fast dividing cells, such as the cells responsible for hair growth. Cats that take vincristine on a long term basis will most likely experience a loss of hair. This seems to worsen over time.

    Neurological

    • Cats can develop vincristine toxicity or too much of the drug in their system. This can cause anything from a mild seizure to complete system failures. Veterinarians keep a close watch on blood counts and these extreme side effects are rare. Common neurological side effects are a general weakness in the cat or lethargy. Pet owners may also see the cat walking off balance or seem to have less control over where it places its feet when walking as if its feet are asleep.