Vincristine: veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

Oncovin, Vincristine sulphate, Cytocristin

Species with doses

Dogs, Cats and Horses

Routes

IV

Last reviewed

1 October 2026

Indications

• Lymphoma / lymphoid leukaemia (multidrug CHOP-type protocols)
• Transmissible venereal tumour (TVT) — often curative as monotherapy
• Immune-mediated thrombocytopenia (rapid platelet increase, adjunct)
• Other vincristine-sensitive tumours (some sarcomas/carcinomas, per protocol)

Vincristine dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Lymphoma / transmissible venereal tumour: Dosed by BODY SURFACE AREA. Papich 5e: 0.5–0.75 mg/m² (or 0.025–0.05 mg/kg) IV once weekly. Plumb’s p.1168: 0.5–0.75 mg/m² IV every 1–2 weeks in combination protocols; TVT as sole therapy 0.5 mg/m² (max 1 mg) weekly for 4–6 weeks. Strict IV technique — vesicant. Consult an oncologist.
• Immune-mediated thrombocytopenia (adjunct): Plumb’s p.1168: 0.5 mg/m² IV when platelets <10–20,000/µL or bleeding (Saxon); 0.5–0.7 mg/m² bolus or 4–6 h infusion if refractory to prednisone (Trepanier); 0.02 mg/kg IV once (Cohn). Papich 5e: 0.02 mg/kg IV once a week with prednisolone.

Cats

• Lymphoma (per protocol): Dosed by BODY SURFACE AREA. Papich 5e: dogs and cats 0.5–0.75 mg/m² IV weekly. Plumb’s p.1168: cats 0.5–0.75 mg/m² IV every 1–3 weeks. Vesicant; consult an oncologist.

Horses

• Lymphoma (CAP protocol adjunct): Plumb’s p.1168 (Mair & Couto 2006): 0.5 mg/m² IV weekly, added to the cytarabine/cyclophosphamide/prednisolone protocol if there is no response. Oncologist input recommended.

Contraindications

Pre-existing significant myelosuppression (neutropenia), severe hepatic impairment (hepatic clearance — reduce dose), and peripheral neuropathy. Perivascular administration (vesicant — necrosis). Pregnancy. Known hypersensitivity. Intrathecal use is FATAL (IV only).

Species-specific warnings

Cats: Small body size makes BSA dosing error-prone — calculate carefully; cats may be sensitive to GI and marrow toxicity.

Adverse effects

• Myelosuppression (neutropenia — usually milder than other chemo agents)
• GI: vomiting, diarrhoea, anorexia, ileus (constipation)
• Peripheral neuropathy (dose-related)
• Severe tissue necrosis if extravasated (vesicant)
• Alopecia (in continuously growing coats)

Drug interactions

• Other myelosuppressive chemo: additive marrow suppression (built into protocols)
• CYP3A inhibitors (azoles, macrolides): raise vincristine levels → increased toxicity
• Drugs causing neuropathy: additive peripheral neurotoxicity
• L-asparaginase: timing affects vincristine clearance (give vincristine first per protocol)

Pregnancy and lactation

Contraindicated in pregnancy (cytotoxic/teratogenic). Handle with cytotoxic precautions; pregnant staff should not handle/administer.

Monitoring

• CBC before each dose (neutrophil count — delay/reduce if neutropenic)
• IV catheter placement/patency (clean stick; vesicant) and the site afterwards
• GI signs (ileus/constipation) and peripheral neuropathy
• Tumour response (e.g. TVT regression); cumulative dose

Toxicity and overdose

Dose-limiting toxicities are myelosuppression (neutropenia nadir), GI toxicity (including ileus/constipation), and peripheral neuropathy. EXTRAVASATION is a major hazard — severe, progressive tissue necrosis. Accidental intrathecal administration is fatal. Overdose intensifies all of these.

Management: No specific antidote. Supportive/intensive care: manage neutropenic sepsis (antibiotics, ± G-CSF), GI support, and neuropathy. For EXTRAVASATION: stop, aspirate, apply WARM compresses and (per oncology guidance) consider hyaluronidase infiltration; do not use cold. Monitor CBC closely; severe overdose has a guarded prognosis.

Clinical pearls

• Dose by BODY SURFACE AREA (mg/m²), not mg/kg — and double-check the calculation; it is a cytotoxic with a narrow margin
• The drug of choice for TVT — often curative in a few weekly doses as a single agent
• A clever adjunct in immune-mediated thrombocytopenia: it transiently boosts platelet counts
• VESICANT — a perfect, single-stick IV is essential; extravasation causes devastating necrosis (warm compress + hyaluronidase if it happens)
• Generally less myelosuppressive than other chemo agents, but still check the CBC before every dose; handle with full cytotoxic precautions

Mechanism of action

Binds tubulin and inhibits microtubule polymerisation, arresting the mitotic spindle in metaphase so dividing (cancer) cells cannot complete mitosis and undergo apoptosis — cell-cycle (M-phase) specific cytotoxicity. Its effect on megakaryocyte microtubules is thought to underlie the platelet release used in immune-mediated thrombocytopenia.

Formulations and products

• Injection 1 mg/mL
• Oncovin / Vincristine — 1 mg/mL (1 / 2 mg vial), Injection (human-label)
• Cytocristin — 1 mg / 2 mg vial, Injection (human-label)

Storage

Injection: REFRIGERATE (2–8 °C), protect from light. Handle as a hazardous cytotoxic drug (closed-system/gloves/PPE); dispose appropriately.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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Frequently asked questions