The lowest effective dose should be administered, and, as with all anaesthetics, the correct dose is to effect. Isoflurane should be administered using an accurately calibrated vaporizer in association with an appropriate anaesthetic circuit; however, a non-precision, uncompensated vaporizer (eg Stephens vaporizer, Komesaroff machine) is also suitable for tile delivery of isoflurane.

Minimum Alveolar Concentration: The MAC value of isoflurane in the horse is approximately 1.31%.

Induction of anaesthesia: As it is not normally practicable to induce anaesthesia in adult horses using isoflurane, induction should usually be achieved by the use of a short acting barbiturate, such as thiopentone sodium, or ketamine and may include guaiphenesin. Concentrations of 3 to 5% isoflurane may then be used to achieve the desired depth of anaesthesia in 5 to 10 minutes.

Isoflurane at a concentration of 3 to 5% in a high flow of oxygen may be used for induction in foals.

Maintenance of anaesthesia: Anaesthesia may be maintained using 1.5% to 2.5% isoflurane.

Minimum Alveolar Concentration: Few MAC/ED50 values have been recorded. Examples are 1.34% for the Sandhill crane, 1.45% for the homing pigeon, reduced to 0.89% by the administration of midazolam and 1.44% for cockatoos, reduced to 1.08% by the administration of butorphanol analgesic.

The use of isoflurane anaesthesia has been reported for many species, from small birds such as zebra finches, to large birds such as vultures, eagles and swans.

Induction of anaesthesia: Induction with 3 to 5% isoflurane is normally rapid. Induction of anaesthesia with propofol, followed by isoflurane maintenance, has been reported for swans.

Maintenance of anaesthesia: The maintenance dose depends on the species and individual. Generally, 2 to 3% is suitable and safe.

Only 0.6 to 1% may be needed for some stork and heron species.

Up to 4 to 5% may be needed for some vultures and eagles.

Up to 3.5 to 4% may be needed for some ducks and geese.

Generally, birds respond very rapidly to changes in concentration of isoflurane.

Minimum Alveolar Concentration: The literature records its use on a wide variety of reptiles (e.g. various species of lizard, tortoise, iguanas, chameleon and snakes). The ED50 was determined in the desert iguana to be 3.14% at 35°C and 2.83% at 20°C.

Induction of anaesthesia: Induction is usually rapid at 2 to 4% isoflurane. Reptiles may be difficult to induce with inhalation agents due to breath holding.

Maintenance of anaesthesia: 1 to 3% is a typical concentration.

Minimum Alveolar Concentration: Isoflurane has been recommended for anaesthesia of a wide variety of small mammals, e.g. rat, mouse, hamster, chinchilla, gerbil, guinea pig, ferret and rabbit. The MAC value for mice has been cited as 1.34%, for rat as 1.38 to 2.4% and rabbit as 2.05%.

Induction of anaesthesia: Isoflurane concentration 2 to 3%.

Maintenance of anaesthesia: Isoflurane concentration 0.25 to 2%.

Minimum Alveolar Concentration: The MAC for isoflurane is 1.28% in the dog.

Induction of anaesthesia: Anaesthesia of dogs may be induced by inspired isoflurane concentrations between 2 and 4%. The use of common preanaesthetic agents such as acepromazine, opioids, benzodiazepines and the alpha-2-adrenoreceptor agonists, and/or concurrent use of nitrous oxide reduce the concentration of isoflurane required. If anaesthesia is induced with an injectable agent, an initial isoflurane concentration slightly above that required for maintenance should usually be administered to aid the transition onto gaseous anaesthesia.

Maintenance of anaesthesia: As a general rule, surgical anaesthesia can be maintained with end tidal concentrations of around 1.3 MAC. In practice, vaporizer settings (VOC) of 1.5 to 2.5% in the dog are used. Again, premedication and/or concurrent use of nitrous oxide or the use of sedatives and/or analgesics during anaesthesia reduces the concentration of isoflurane required. Recovery is usually smooth and rapid.

Minimum Alveolar Concentration: The MAC of isoflurane is 1.63% in the cat.

Induction of anaesthesia: Anaesthesia of cats may be induced by inspired isoflurane concentrations of between 2 and 4%. The use of common preanaesthetic agents such as acepromazine, opioids, benzodiazepines and alpha-2-adrenoreceptor agonists, and/or concurrent use of nitrous oxide reduce the concentration of isoflurane required. If anaesthesia is induced with an injectable agent, an initial isoflurane concentration slightly above that required for maintenance should usually be administered to aid the transition onto gaseous anaesthesia.

Maintenance of anaesthesia: As a general rule, surgical anaesthesia can be maintained with end tidal concentrations of around 1.3 MAC. In practice, vaporizer settings (VOC) of 1.5 to 3.0% in the cat are used. Again, premedication and/or concurrent use of nitrous oxide or the use of sedatives and/or analgesics during anaesthesia reduces the concentration of isoflurane required. Recovery is usually smooth and rapid.