POM-V Prescription Required Companion Animal

VetOne Fluriso 1000 mg/g Inhalation Vapour Liquid

Active ingredient: Isoflurane

Form

Inhalation vapour, liquid

Species

Cats Chinchilla Dogs Ferrets Gerbil Guinea Pig Hamster Horses Mouse Ornamental Birds Rat Reptiles

Manufacturer

Piramal Critical Care Limited

VMD MA No.

37071/5003

What it's used for

Induction and maintenance of general anaesthesia.

Full indications, dosage and side effects ↓

View official SPC (PDF)

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Paying less for Isoflurane

1

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2

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The CMA found online pharmacies 50–60% cheaper than practice dispensing on common medicines — typically £200–£300 a year.

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Clinical information

VetOne Fluriso 1000 mg/g Inhalation Vapour Liquid — SPC Details

Source: VMD Summary of Product Characteristics (SPC). Last updated 26 Mar 2026.

Induction and maintenance of general anaesthesia.

Inhalation use
Isoflurane should be administered using an accurately calibrated vaporiser
in an appropriate anaesthetic circuit, since levels of anaesthesia may be
altered rapidly and easily.
Isoflurane may be administered in oxygen or oxygen/nitrous oxide
mixtures.
The MAC (minimum alveolar concentration in oxygen) or effective dose
ED50 values and suggested concentrations given below for the target

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species should be used as a guide or starting point only. The actual
concentrations required in practice will depend on many variables,
including the concomitant use of other drugs during the anaesthetic
procedure and the clinical status of the patient.
Isoflurane may be used in conjunction with other drugs commonly used in
veterinary anaesthetic regimes for premedication, induction and analgesia.
Some specific examples are given in the individual species information.
The use of analgesia for painful procedures is consistent with good
veterinary practice.
Recovery from isoflurane anaesthesia is usually smooth and rapid. The
analgesic requirements of the patient should be considered before the
termination of general anaesthesia.
HORSE
The MAC for isoflurane in the horse is approximately 1.31%
Premedication
Isoflurane may be used with other drugs commonly used in veterinary
anaesthetic regimes. The following drugs have been found to be
compatible with isoflurane: acepromazine, alfentanil, atracurium,
butorphanol, detomidine, diazepam, dobutamine, dopamine,
guaiphenesin, ketamine, morphine, pentazocine, pethidine, thiamylal,
thiopentone and xylazine. Drugs used for premedication should be
selected for the individual patient. However, the potential interactions
below should be noted.
Interactions
Detomidine and xylazine have been reported to reduce the MAC for
isoflurane in horses.
Induction
As it is not normally practicable to induce anaesthesia in adult horses
using isoflurane, induction should be by the use of a short acting
barbiturate such as thiopentone sodium, ketamine or 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 oxygen may be
used for induction in foals.

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Maintenance
Anaesthesia may be maintained using 1.5% to 2.5% isoflurane.
Recovery
Recovery is usually smooth and rapid.
DOG
The MAC for isoflurane in the dog is approximately 1.28%.
Premedication
Isoflurane may be used with other drugs commonly used in veterinary
anaesthetic regimes. The following drugs have been found to be
compatible with isoflurane: acepromazine, atropine, butorphanol,
buprenorphine, bupivacaine, diazepam, dobutamine, ephedrine,
epinephrine, etomidate, glycopyrrolate, ketamine, medetomidine,
midazolam, methoxamine, oxymorphone, propofol, thiamylal, thiopentone
and xylazine. Drugs used for premedication should be selected for the
individual patient. However, the potential interactions below should be
noted.
Interactions
Morphine, oxymorphone, acepromazine, medetomidine, medetomidine
plus midazolam have been reported to reduce the MAC for isoflurane in
dogs.
The concomitant administration of midazolam/ketamine during isoflurane
anaesthesia may result in marked cardiovascular effects, particularly
arterial hypotension.
The depressant effects of propanolol on myocardial contractility are
reduced during isoflurane anaesthesia, indicating a moderate degree of
receptor activity.
Induction
Induction is possible by face mask using up to 5% isoflurane, with or
without premedication.
Maintenance
Anaesthesia may be maintained using 1.5% to 2.5% isoflurane.

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Recovery
Recovery is usually smooth and rapid.
CAT
The MAC for isoflurane in the cat is approximately 1.63%.
Premedication
Isoflurane may be used with other drugs commonly used in veterinary
anaesthetic regimes. The following drugs have been found to be
compatible with isoflurane: acepromazine, atracurium, atropine, diazepam,
ketamine, and oxymorphone. Drugs used for premedication should be
selected for the individual patient. However, the potential interactions
below should be noted.
Interactions
Intravenous administration of midazolam- butorphanol has been reported
to alter several cardio-respiratory parameters in isoflurane- induced cats
as has epidural fentanyl and medetomidine. Isoflurane has been shown to
reduce the sensitivity of the heart to adrenaline (epinephrine).
Induction
Induction is possible by face mask using up to 4% isoflurane, with or
without premedication.
Maintenance
Anaesthesia may be maintained using 1.5% to 3% isoflurane.
Recovery
Recovery is usually smooth and rapid.
ORNAMENTAL BIRDS
Few MAC/ED50 values have been recorded. Examples are 1.34% for the
Sandhill crane, 1.45% for the racing 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.

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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.
Drug interactions/compatibilities
Propofol has been demonstrated in the literature to be compatible with
isoflurane anaesthesia in swans.
Interactions
Butorphanol has been reported to reduce the MAC for isoflurane in
cockatoos. Midazolam has been reported to reduce the MAC for
isoflurane in pigeons.
Induction
Induction with 3 to 5% isoflurane is normally rapid. Induction of
anaesthesia with propofol, followed by isoflurane maintenance, has been
reported for swans.
Maintenance
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.
3.5 to 4% may be needed for some ducks and geese.
Generally, birds respond very rapidly to changes in concentration of
isoflurane.
Recovery
Recovery is usually smooth and rapid.
REPTILES
Isoflurane is considered by several authors to be the anaesthetic of choice
for many species. The literature records its use on a wide variety of
reptiles (eg. various species of lizard, tortoise, iguanas, chameleon and
snakes).
The ED50 was determined in the desert iguana to be 3.14% at
2.83% at 20˚C.

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Drug interactions/ compatibilities
No specific publications on reptiles have reviewed compatibilities or
interactions of other drugs with isoflurane anaesthesia.
Induction
Induction is usually rapid at 2 to 4% isoflurane.
Maintenance
1 to 3% is a useful concentration
Recovery
Recovery is usually smooth and rapid
RATS, MICE, HAMSTERS, CHINCHILLAS, GERBILS, GUINEA PIGS
AND FERRETS
Isoflurane has been recommended for anaesthesia of a wide variety of
small mammals.
The MAC for mice has been cited as 1.34%, and for the rat as 1.38%,
1.46% and 2.4%.
Drug interactions/ compatibilities
No specific publications on small mammals have reviewed compatibilities
or interactions of other drugs with isoflurane anaesthesia.
Induction
Isoflurane concentration 2 to 3%.
Maintenance
Isoflurane concentration 0.25 to 2%.

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Recovery
Recovery is usually smooth and rapid.
SpeciesMAC (%)Induction (%)Maintenance
(%)
RecoveryHorse1.313.0 – 5.0
(foals)
1.5 – 2.5Smooth and
rapid
Dog1.28Up to 5.01.5 – 2.5Smooth and
rapid
Cat1.63Up to 4.01.5 – 3.0Smooth and
rapid
Ornamental
birds
See posology3.0 – 5.0See posologySmooth and
rapid
ReptilesSee posology2.0 – 4.01.0 – 3.0Smooth and
rapid
Rats, mice,
hamsters,
chinchillas,
gerbils, guinea
pigs and
ferrets
1.34 (mouse)
1.38/1.46/2.40
(rat)
2.0 – 3.00.25 – 2.0
Smooth and
rapid

Do not use in cases of known susceptibility to malignant hyperthermia.
Do not use in cases of known hypersensitivity to isoflurane.

Isoflurane produces hypotension and respiratory depression in a dose-
related manner. Cardiac arrhythmias and transient bradycardia have been
reported rarely.
Cardiac and/or respiratory arrest has been very rarely reported.
Malignant hyperthermia has been reported very rarely in susceptible
animals.
The frequency of adverse reactions is defined using the following
convention:
- very common (more than 1 in 10 animals displaying adverse reaction(s)
during the course of one treatment)
- common (more than 1 but less than 10 animals in 100 animals treated)
- uncommon (more than 1 but less than 10 animals in 1,000 animals
treated)
- rare (more than 1 but less than 10 animals in 10,000 animals treated)
- very rare (less than 1 animal in 10,000 animals treated, including isolated
reports).

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Isoflurane has little or no analgesic properties. Adequate analgesia should
always be given before surgery. The analgesic requirements of the patient
should be considered before general anaesthesia is ended.
The ease and rapidity of alteration of the depth of anaesthesia with
isoflurane and its low metabolism, may be considered advantageous for

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its use in special groups of patients such as the old or young, and those
with impaired hepatic, renal or cardiac function.

Special precautions for use in animals
The use of the product in patients with cardiac disease should be
considered only after a risk/ benefit assessment by the veterinarian.
It is important to monitor breathing and pulse for the frequency and its
features. Respiratory arrest should be treated by assisted ventilation. It is
important to maintain airways free and properly oxygenate tissues during
the maintenance of anaesthesia. In the case of cardiac arrest, perform a
complete cardio pulmonary resuscitation.
The metabolism of isoflurane in birds and small mammals, can be affected
by decreases in body temperature, that may occur secondary to a high
surface area to body weight ratio. Therefore body temperature should be
monitored and kept stable during treatment.
Drug metabolism in reptiles is slow and highly dependent upon
environmental temperature. Reptiles may be difficult to induce with
inhalation agents due to breath holding.
Like other inhalation anaesthetics of this type, isoflurane depresses the
respiratory and cardiovascular systems.
When using isoflurane to anaesthetise an animal with a head injury,
consideration should be given as to whether artificial ventilation is
appropriate to help avoid increased cerebral blood flow by maintaining
normal CO2 levels.
Special precautions to be taken by the person administering the veterinary
medicinal product to animals
•
Authority for advice on Occupational Exposure Standards for isoflurane.
•
ventilation or scavenging systems to prevent the accumulation of
anaesthetic vapour.
•
•
breast- feeding women should not have any contact with the product
and should avoid operating rooms and animal recovery areas.
•
maintenance of general anaesthesia.

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•
of isoflurane during maintenance of general anaesthesia.
•
removed immediately using an inert and absorbent material e.g.
sawdust.
•
mouth.
•
exposure, seek urgent medical assistance and show this label.
•
isoflurane this is an idiosyncratic response very rarely seen after
repeated exposure.
•
supportive treatment. Note that adrenaline and catecholamines may
cause cardiac dysrhythmias.
Other Precautions
Although anaesthetics have a low potential for damage to the atmosphere,
it is good practice to use charcoal filters with scavenging equipment,
rather than to discharge them into the air.

interaction
The action of muscle relaxants in man, especially those of the
nondepolarising (competitive) type such as atracurium, pancuronium or
vecuronium, is enhanced by isoflurane. Similar potentiation might be
expected to occur in the target species, although there is little direct
evidence to this effect. Concurrent inhalation of nitrous oxide enhances
the effect of isoflurane in man and similar potentiation might be expected
in animals.
The concurrent use of sedative or analgesic drugs is likely to reduce the
level of isoflurane required to produce and maintain anaesthesia. For
example, opiates, alpha-2-agonists, acepromazine, and benzodiazepines
have been reported to reduce the MAC values.
Some examples are given in 4.9.
Isoflurane has a weaker sensitising action on the myocardium, to the
effects of circulating dysrhythmogenic catecholamines, than halothane.
Isoflurane may be degraded to carbon monoxide by dried carbon dioxide
absorbents.

Do not store above 25°C. Protect from direct sunlight & direct heat.

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Store in tightly closed original container.

(foals)
1.5 – 2.5Smooth and
rapid
Dog1.28Up to 5.01.5 – 2.5Smooth and
rapid
Cat1.63Up to 4.01.5 – 3.0Smooth and
rapid
Ornamental
birds
See posology3.0 – 5.0See posologySmooth and
rapid
ReptilesSee posology2.0 – 4.01.0 – 3.0Smooth and
rapid
Rats, mice,
hamsters,
chinchillas,
gerbils, guinea
pigs and
ferrets
1.34 (mouse)
1.38/1.46/2.40
(rat)
2.0 – 3.00.25 – 2.0
Smooth and
rapid
4.10 Overdose (symptoms, emergency procedures, antidotes) if
necessary
Isoflurane overdose may result in profound respiratory depression.
Therefore, respiration must be monitored closely and supported when
necessary with supplementary oxygen and/ or assisted ventilation.
In cases of severe cardiopulmonary depression, administration of
isoflurane should be discontinued, the breathing circuit should be flushed
with oxygen, the existence of a patent airway ensured, and assisted or
controlled ventilation with pure oxygen initiated. Cardiovascular
depression should be treated with plasma expanders, pressor agents,
antiarrhythmic agents or other appropriate techniques.
4.11 Withdrawal period(s)
Horses:
Meat and offal: 2 days
Not authorised for use in mares producing milk for human consumption.

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5.

This information is sourced from the official Summary of Product Characteristics (SPC) published by the Veterinary Medicines Directorate (VMD). It is provided for informational purposes only and does not replace professional veterinary advice. Always consult your vet before administering any medication.