Pentobarbital (Pentobarbitone): veterinary dose and monograph

At a glance

Drug class

Sedative / anaesthetic

Also known as

Pentobarbitone, Nembutal, Euthanasia solution (component)

Species with doses

Dogs, Cats, Cattle, Horses, Goats and Sheep

Routes

IV

Last reviewed

1 October 2026

Indications

• Refractory status epilepticus / cluster seizures unresponsive to first-line drugs (anaesthetic barbiturate)
• Humane EUTHANASIA (concentrated solution)
• Short-term anaesthesia/heavy sedation (historical/specialist)

Pentobarbital (Pentobarbitone) 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

• Refractory status epilepticus (to effect): Papich 5e: status epilepticus 2–6 mg/kg IV (15–20 min for full effect); CRI 2–15 mg/kg IV to effect then 0.2–1 mg/kg/h. Plumb’s p.952: 3–15 mg/kg IV to effect — it stops the physical seizure but is not a true anticonvulsant (Platt; Fletcher). Intubate and ventilate; expect hypothermia and hypotension.
• CRI (refractory seizures / ventilator sedation): Papich 5e: 0.2–1 mg/kg/h after a 2–15 mg/kg loading dose. Plumb’s p.952 (Brainard 2008): ventilator maintenance 1–3 mg/kg/h; switch to propofol ~12 h before weaning.
• Euthanasia: Follow the specific euthanasia-solution label; sedate first if needed; confirm death. Controlled drug — record use.

Cats

• Refractory status epilepticus: Plumb’s p.952: 5–15 mg/kg IV to effect (Morgan); 3–15 mg/kg IV slowly to heavy sedation, repeat in 4–8 h if needed (Raffe). Papich 5e: 2–6 mg/kg IV. Ventilator sedation CRI 1–3 mg/kg/h. For euthanasia use the euthanasia-solution label dose.

Cattle

• Euthanasia: Carcass is a relay-toxicosis hazard to scavengers and dogs — prevent access; deep burial or incineration. Carcass must not enter the food chain.

Horses

• Euthanasia: Sedate first (e.g. xylazine or detomidine). Carcass disposal must prevent scavenger access (relay toxicosis).

Goats

• Euthanasia: Carcass relay-toxicosis hazard — dispose of appropriately.

Sheep

• Euthanasia: Carcass relay-toxicosis hazard — dispose of appropriately.

Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

• Euthanasia: Carcass is a relay-toxicosis hazard to scavengers and dogs — prevent access; deep burial or incineration. Carcass must not enter the food chain.

Contraindications

Use of the EUTHANASIA solution for anything other than euthanasia. Anticonvulsant use without airway/ventilation support (causes apnoea at anaesthetic doses). Perivascular injection (irritant). Severe hepatic disease (prolonged effect, anticonvulsant use). Known barbiturate hypersensitivity. Carcass disposal must prevent scavenger access (relay toxicosis).

Species-specific warnings

Horses: Sedate before euthanasia and use adequate volume; ensure carcass disposal prevents scavenger access (relay pentobarbital toxicosis in dogs/wildlife).

Adverse effects

• Profound respiratory depression / apnoea (anaesthetic doses)
• Hypotension, myocardial depression
• Excitement during induction/recovery without premed; prolonged recovery
• Perivascular irritation

Drug interactions

• Other CNS depressants/anaesthetics: additive, profound depression
• Hepatic enzyme INDUCER (chronic): increases metabolism of many co-drugs
• Highly protein-bound — displacement increases free drug
• Acidic/incompatible IV drugs: precipitation

Pregnancy and lactation

Crosses the placenta (neonatal depression). Used when seizure control is essential; euthanasia context aside.

Monitoring

• Seizure control vs respiratory depression (anticonvulsant use) — airway/ventilation support mandatory
• For euthanasia: confirm death (cardiac arrest, no reflexes)
• Controlled-drug accountability records
• Safe carcass disposal (prevent scavenger relay toxicity)

Toxicity and overdose

At anaesthetic/euthanasia doses it causes the intended profound respiratory and cardiovascular depression. Accidental human exposure (needlestick/ingestion) is dangerous. RELAY toxicosis is a serious hazard — scavengers (dogs, wildlife, raptors) that eat a pentobarbital-euthanised carcass can be poisoned/killed; carcasses must be disposed of to prevent access.

Management: For unintended anaesthetic overdose: support ventilation (intubate/ventilate) and circulation (fluids, vasopressors); there is no reversal agent — recovery requires time and support. (In euthanasia, profound depression is the intended effect.) Human exposure: emergency medical care.

Clinical pearls

• Two very different roles — anaesthetic-dose barbiturate for REFRACTORY status epilepticus (intubate and ventilate!), and the gold-standard EUTHANASIA agent
• Keep the concentrated EUTHANASIA solution rigorously separated and labelled to prevent a catastrophic dosing error
• Warn owners/disposal services about RELAY toxicity — a euthanised carcass can poison scavengers; bury deeply/cremate per regulations
• No reversal agent — anticonvulsant use demands full airway and ventilatory support
• A controlled drug — meticulous records are mandatory

Mechanism of action

A barbiturate that potentiates GABA-A inhibition (prolonging chloride-channel opening) and at higher doses directly opens the channel, producing dose-dependent CNS depression from sedation through anaesthesia to medullary (respiratory/cardiovascular) collapse. Anticonvulsant doses suppress seizure activity; euthanasia doses cause rapid loss of consciousness followed by respiratory and cardiac arrest.

Formulations and products

• Injection 60 mg/mL (anaesthetic/anticonvulsant grade)
• Euthanasia solution ~200–400 mg/mL (pentobarbital ± phenytoin)
• Pentobarbital euthanasia solution (Various) — ~390 mg/mL (± phenytoin), Injection (euthanasia)
• Pentobarbital (Nembutal) — 60 mg/mL injection, Injection (human-label)

Storage

Controlled-drug SECURE storage with strict records; 15–30 °C, protect from light. Clearly segregate euthanasia solution from anaesthetic/anticonvulsant stock to prevent error.

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.

Other sedatives and anaesthetics

• Isoflurane
• Ketamine HCl
• Medetomidine
• Midazolam
• Phenobarbital
• Propofol
• Romifidine
• Sevoflurane

Frequently asked questions