Bolton Ferret Welfare

Anaesthesia of Pet Ferrets (part one)

by Anna Meredith MA VetMB CertLAS DZooMed MRCVS Royal [Dick] School of Veterinary Studies (2013)

Many of the same anaesthetic drugs and equipment used in small animal practice are suitable for use in ferrets, with some minor modifications. The veterinary surgeon should however, be aware of any unique anatomical or physiological differences between ferrets and more commonly encountered species such as the dog and cat.

Anatomical and Physiological Considerations

Due to their relatively small body size and fast metabolic rate drugs are rapidly metabolised and eliminated. A shorter duration of action of anaesthetic drugs should therefore be expected. Ferrets are also more susceptible to development of hypoglycaemia as a direct result of more rapid use of metabolites and in some cases underlying disease, such as insulimona. Their relatively small body size may also present difficulties with intubation and venous access. A large ratio of surface area to volume increases the heat loss from the body during anaesthesia, increasing the likelihood of hypothermia developing and prolonged recovery times. Where possible heat loss should be minimised using external heat sources, minimal hair clipping of the surgical site, warming surgical scrub solution, avoiding alcohol surgical preparations and minimising length of the surgical procedure.

Pre-anaesthetic Considerations

Prior to anaesthesia always carry out a thorough clinical examination to assess whether there is any underlying disease. This is of vital importance and appropriate diagnostic tests should be applied if disease processes are suspected. A variety of illnesses commonly occur in pet ferrets such as anaemia, lymphoma, adrenal gland disease and cardiomyopathy (deterioration of the myocardium {heart muscle}) and these will influence the anaesthetic regime to be used. If the patient is dehydrated and/or is anorexic, correct any deficits before surgery commences. Weigh the animal, so accurate drug dosages can be calculated and fluid losses can be assessed. It is a good idea to monitor pre-operative food and water intake so that recovery can be assessed. Baseline values for respiration, heart rate and temperature should be determined for reference during anaesthesia. Ferrets, like may carnivores, vomit easily. Ferrets should be fasted prior to induction for 2 - 4 hours, with water being removed 2 hours prior to induction. In older ferrets fast periods should be reduced to 2 hours since there is an increased risk of insulimona in these ferrets.

Table 1: Normal Physiological Values for Pet Ferrets

Rectal Temperature37.8 - 40oC
Heart Rate180 - 250 beats per minute
Average Blood Volume
Sulphate (umol/L)
Adult Male - 60ml
Adult Female - 40ml

Anaesthesia

Ferrets may be anaesthetised with similar anaesthetic regimes as those used in cats. Routes of administration of drugs are outlined in the following table.

Table 2: Routes for Parenteral Administration of Drugs in Ferrets

Intramuscular
SubcutaneousIntravenous
Quadriceps Muscle
Epaxial Muscles*
Scruff area
Flank area
Cephalic Vein
Jugular Vein
Lateral Saphenous Vein

* Care with this site since kidney puncture is a potential complication.

Sedation and Premedication

Ferrets readily salivate, particularly when induced with a ketamine combination and an anticholinergic premedication should be administered, for example atropine.

Ferrets are very easily stressed by physical restraint, so sedation is vital especially prior to induction by inhalation. Sedatives and premedicants commonly used in ferrets are outlined in table 3.

Table 3: Premedication and Sedation Drug doses in Ferrets

DrugDose SC or IM
(mg/kg)
Comments
Atropine0,05Anticholinergic
Acepromazine0.1 - 0.3Moderate Sedation
Diazepam2Light Sedation
Ketamine 20 - 30 Immobilisation, some analgesia
Medetomidine* 0.1 - 0.5 Good sedation, with analgesia
Midazolam 1 Light Sedation
Xylazine* 1 - 2 Good sedation, with analgesia
Fentanyl/Fluanisone
('Hypnorm')
0.5ml/kg Immobilisation, good analgesia, reversal possible
Midazolam, Ketamine,
Atropine Combination
0.3 + 5 - 10 + 0.02 respectively

* Reverse with 1mg/kg atipamezole

Alpha-2 agonists should be used with care in sick or debilitated animals or in ferrets with suspected cardiac or endocrine disease. Fentanyl/Fluanisone ('Hypnorm' - Janssen) is a good sedative for ferrets and is relatively safe in sick animals.

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