This is considered a short acting barbiturate. The duration of anesthesia is dose dependent and a typical induction dose would wear off in about 10 to 30 minutes in an adult dog. The reason for this prolonged recovery is that this drug is redistributed from the blood into fat. Since puppies have very little body fat for the drug to redistribute into, they tend to suffer from a prolonged recovery period when this class of drugs is used. Barbiturates should never be used in a puppy younger than 8 weeks of age.
Barbiturates also have a depressing effect on respiration and heart rate.
Halothane was the gas of choice before isoflurane became available. Because of this, it provides slightly better pain relief in the immediate post operative period. Methoxyflurane was used by many veterinarians for a long time. This is great for pain relief, but not so good for the liver. In short nosed dogs, it can also present a problem with the airway as it takes so long for them to wake up.