Anaesthesia of Pet Ferrets (part two)
by Anna Meredith MA VetMB CertLAS DZooMed MRCVS Royal [Dick] School of Veterinary Studies
Ferrets are candidates for IV induction (cephalic or jugular vein). The combination of fentanyl/fluanisone plus midazolam is probably the one of choice, although many other drugs and combinations are possible, such as ketamine plus an alpha-2 agonist (eg medetomidine) or benzodiazepine. Alphaxalone/alphadalone can be used intravenously in the ferret. This provides good surgical anaesthesia for 10 – 15 minutes.
|Drug Dose||(mg/kg)||Duration of Action|
|Alphaxalone/alphadalone||8 - 12 IV||10 - 15 minutes|
|Ketamine/ACP||25 IM + 0.25 IM||20 - 30 minutes|
|Ketamine/Diazepam||25 IM + 2 IM||20 - 30 minutes|
|Ketamine/Medetomidine*||8 IM + 0.1 IM||20 - 30 minutes|
|Dose same as for a cat||20 - 40 minutes|
|'Hypnorm'/Midazolam**||0.5ml/kg IM + 1 IV to effect||20 - 40 minutes|
* Reverse with 1mg/kg atipamezole
** Reverse with butorphanol or buprenorphine IV (for doses see under analgesia)
It is good practice to provide oxygen via face mask or ET tube to any animal when under injectable anaesthesia. A volatile agent can then be added to prolong the anaesthetic period if necessary.
Halothane, methoxyflurane and isoflurane can all be safely used to induce and maintain anaesthesia in ferrets. Induction and recovery are most rapid with isoflurane. Ferrets may be induced in a chamber, and then maintained with a mask. The author prefers to use prior sedation since without this animals become easily distressed. It should be noted that isoflurane decreases the packed cell volume in ferrets and this should be taken into account if blood samples are taken using this anaesthetic.
The circuit of choice is an Ayre's T-piece with a flow rate of 1 - 3.5 litres/minute depending on size of animal, or a commercially available concentric face masks that scavenge waste gases using a vacuum system. Ferrets can be easily intubated using a Wisconsin size 1 laryngoscope blade and a 2.5 - 3.5mm endotracheal tube. Local anaesthetic spray should be applied beforehand to the glottis to prevent laryngospasm.
A primary concern is prevention of hypothermia as previously discussed. Cooling by the flow of oxygen and anaesthetic gases can also be significant. The animal should be placed on a heat pad or an overhead heat lamp should be used, but beware of overheating. Body temperature should be monitored throughout the procedure using either a rectal probe or a digital thermometer. The ferret may be insulated using bubble wrap or tin foil.