Plus-Hex CLINICAL
Fish
Fish should be left immersed in an anaesthetic solution for 20 – 30 minutes. This solution can be MS-222, Aqua-Sed, clove oil( 17 mg / l) or isoflurane( 5 – 20 ml / l) [ 14 ]. Pentobarbital can then be administered via the intravenous, intracardiac or intracoelomic route.
All use of MS-222 in any species should be in conjunction with a buffer agent such as sodium bicarbonate. When using isoflurane, there must be adequate ventilation in the room and personal protective equipment should be worn to minimise risk to staff.
Alfaxalone can also be added to the water at a rate of 5 – 10 mg / l to provide anaesthesia before the pentobarbital injection [ 6 ]. Anaesthesia takes
[ 15 ].
5.4 minutes to achieve, on average
For larger fish, an injection of ketamine can be given intramuscularly, using the muscles either side of the dorsal fin and inserting the needle in between the scales; this is followed by an injection of pentobarbital.
Figure 2. Blood sampling from the tail vein of a bearded dragon.
Aqua-Sed can also be used alone according to the datasheet at a fourfold dose( 2 – 2.8 ml / l) in a small volume of water for 1 hour [ 16 ].
Death can be confirmed when the fish will no longer roll their eyes from side to side when rocked and breathing movements have ceased for a minimum of 30 minutes.
Frogs
An injection of alfaxalone can be administered intramuscularly [ 17 ], followed by an injection of pentobarbital, which ideally is administered intravenously but can be given intracoelomically.
Prolonged immersion in a high concentration of MS-222( 10 g / l) for up to 1 hour can also be used as a method of euthanasia [ 14 ].
Snakes
Alfaxalone can be administered by intramuscular injection, using the muscles located either side of the spine in the cranial half of the body, to provide sedation before the administration of pentobarbital [ 18 ]. A Doppler probe can be used to locate the heart in the cranial third of the body. An intracardiac injection of pentobarbital is given or, in smaller species, the ventral tail vein may be used.
Hedgehogs
Figure 3. Doppler being used to detect the absence of a heartbeat in a leopard gecko.
Alfaxalone can be injected to induce sedation. Subcutaneous injections can be given by lifting a small fold of skin over the flank or back region and injecting
Volume 40( 6) • December 2025
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