Major Uses

Pentobarbital is a barbiturate that is sometimes used to induce sedation or control epileptic seizures in animals. It is more often used for euthanasia. Barbiturates are central nervous system depressants.

Pentobarbital is a Class II controlled substance and is not typically prescribed or used outside of a veterinary setting. Because of the high risk of respiratory depression and other complications, animals undergoing treatment with this drug require close monitoring during use.

Common Precautions

Side effects vary based on the species being treated and the dose given. Hypothermia is one of the more common side effects associated with use. This drug may cause slowed breathing or excitement in some animals. Because of the drug's respiratory depressant effect, careful monitoring is necessary during use.

Pentobarbital should not be used in animals with porphyria, and it should not be used in the treatment of seizures associated with lidocaine toxicity. Caution is needed when using pentobarbital in animals suffering from liver disease.

A number of supplements and medications are known to interact with pentobarbital, including doxycycline, chloramphenicol, beta blockers, acetaminophen, lidocaine, phenytoin, phenylbutazone, antihistamines, opiates, rifampin, other barbiturates, and many other drugs.

Pentobarbital should not be used in animals with a known allergy or hypersensitivity to the drug. An overdose of pentobarbital can be dangerous or even fatal. Any known or suspected overdose not intended for euthanasia is a medical emergency that requires immediate veterinary attention.


Pentobarbital should be stored in its original packaging, out of the reach of children and animals.


Pentobarbital is available as 16 mg capsules and as tablets in strengths ranging from 15 mg to 100 mg. A pentobarbital elixir is available in concentrations of 15mg/5 ml and 20 mg/5 ml. An injectable form and a suppository are also available.

The typical dose of pentobarbital for oral use as an anesthetic is 14 to 15 mg/lb (28 to 30 mg/kg) on an empty stomach. When given on a full stomach, the medication is dosed at 31.5 mg/lb (63 mg/kg). When administered to control seizures, the typical dose of pentobarbital is 1 to 7.5 mg/lb (2 to 15 mg/kg) intravenously or 2.5 mg/lb/hr (5 mg/kg/hr) intravenously to effect. Two doses of this medication should not be given at once. If a dose of pentobarbital is missed, a veterinarian should be consulted.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.