Vincristine (Oncovin®, Vincasar PFS®) for Dogs and Cats

Overview of Vincristine for Dogs and Cats

Vincristine, also known as Oncovin®, belongs to a group of medications known as vinca alkaloids and is obtained from the plant Cantharanthus roseus. It is often used for dogs and cats to treat malignant cancers of the lymphoid and blood systems.
The drug is commonly used in the treatment of cancer. One of the hallmarks of cancer is the speed at which cancer cells divide.
Vincristine will bind to the proteins of actively dividing cells, preventing cell division and resulting in cell death.
Since cancer cells tend to divide rapidly, the drug will primarily effect these cells. Unfortunately, certain other body cells also divide rapidly, such a hair and gastrointestinal lining cells, resulting in effects on these sites of the body as well.
Vincristine has been shown to induce the release of already existing platelets from the bone marrow in dogs but the exact way this accomplished is not fully understood.
Vincristine is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
This drug is not approved for use in animals by the Food and Drug Administration but it is prescribed legally by veterinarians as an extra-label drug.

Vincristine is used to treat malignant cancers of the lymphoid and blood systems. It has also been used to treat hemangiosarcoma and transmissible venereal tumor.
Vincristine is also used to treat immune-mediated platelet disorders.

While generally safe and effective when prescribed by a veterinarian, vincristine can cause side effects in some animals. As with other cancer treating drugs, vincristine is a strong drug and the potential side effects can be serious.
Vincristine should not be used in animals with known hypersensitivity or allergy to the drug.
Vincristine should be avoided in animals with liver disease, low white blood cell counts, active infections or disease of the nervous system.
Vincristine may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with vincristine.
Toxic effects of vincristine can affect the nervous system, resulting in weakness, collapse or seizure.
This drug has been shown to suppress the immune system in some animals.
Vincristine may cause hair loss, vomiting, nausea or diarrhea.
This medication should only be given intravenous. If injected outside the vein, significant inflammation, including skin necrosis or sloughing, may occur.

Vincristine is available in injectable form only at a concentration of 1 mg/ml in 1ml, 2 ml and 5 ml vials.

Medication should never be administered without first consulting your veterinarian. Due to potential for complications, this medication is only administered in a hospital setting.
Vincristine is commonly used in combination with other drugs to treat cancerous processes at a dose of 0.5 to 0.75 mg/m2 intravenous every 7 to 14 days in dogs.
In cats, vincristine is dosed at 0.125 mg per pound (0.25 mg/kg) IV every 7 to 14 days.
For immune-mediated platelet disorders, vincristine is dosed for dogs at 0.005 to 0.025 mg per pound (0.01 to 0.05 mg/kg) every 4 to 7 days.
The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects.