Chapter 1 Ferrets
Ferrets (Mustela putorius furo) are thought to be a domesticated form of the European polecat (M. putorius) and, not surprisingly, have a history extending back alongside the domestic rabbit. Originally kept as working animals, selective breeding for colour varieties and temperament has resulted in a significant rise in their being kept as pets and show animals.
|Average life span (years)||5–8+|
|Weight (kg) Male||1.0–2.0 kg|
|Body temperature (°C)||37.8–40|
|Respiratory rate (per min)||33–36|
|Heart rate (beats/min)||180–250|
|Age at weaning (weeks)||6–8|
|Sexual maturity||4–8 months (in the first spring following birth – typically March)|
Consultation and handling
Ferrets vary markedly in their temperament; working ferrets are perhaps slightly more unpredictable, whereas pet ferrets are usually well handled and unlikely to bite unless provoked. When handling a ferret, it can be easily restrained around the neck; a towel can be used – draped over the body before grasping the neck to protect from scratching. For those ferrets determined to bite, scruffing and holding with all four legs off the table will usually relax them to allow a reasonable examination.
Many ferrets intensely enjoy certain commercially available dietary supplements, e.g. Ferretone (8 in 1) to the extent that they will readily tolerate some procedures, e.g. ECG, so long as they are supplied with a steady stream of product to lick.
Always weigh the ferret whenever examined, to monitor weight trends. A healthy ferret above ground walks with a dorsal flexure in its back. Hind-leg paresis can be a non-specific sign of ill-health in the ferret due to weakness of the muscle groups needed to maintain this position.
Odour is a feature of ferret life and is likely to be used for transmitting and receiving information about individuals, such as identification, age, sex and sexual readiness. Most of this smell comes from the sebaceous skin glands, which regress following routine castration or ovario-hysterectomy. The anal sacs can produce a strong-smelling liquid, but this tends only to occur if the ferret is frightened. Therefore the routine anal gland removal (‘descenting’) of ferrets is largely pointless and could constitute unnecessary surgery.
Suitable sites for venepuncture are the jugular, cephalic and saphenous veins. Alternatively, the ventral tail artery and veins can be used.
Blood collection from the tail in the ferret
Note that if blood sampling is done under isoflurane anaesthetic, isoflurane has been linked with a reduction in PCV, haemoglobin level and RBC count. In addition, one may need to centrifuge for 20% longer than in other species and collect 3 × plasma volume required. This may be due to increased erythropoiesis from the spleen.
The typical WBC count is neutrophilic with <30% lymphocytes. Absolute and relative increases in lymphocyte counts may indicate lymphosarcoma.
It is not uncommon for ferrets to have two or more pathologic conditions ongoing at the same time. Combinations include variations on insulinomas, hyperadrenocortism, lymphoma and cardiomyopathy. The clinician should always be aware that the situation may be more complicated that it initially appears and be prepared to investigate several possible clinical problems simultaneously.
Avoid gentamicin, as it has been associated with nephrotoxicity and ototoxicity (deafness) in ferrets.
For general principles, see Thermoregulation under ‘Nursing Care’, in Ch. 2, Rabbits.
The normal maintenance daily water intake for ferrets is 75–100 mL/kg per day. In ferrets, the choice of fluid used is indicated as with other mammals. Fluid replacement calculations are as for other species. All fluids should be warmed to 38°C.
Recommended fluid replacement rates for ferrets
Analgesic doses for ferrets are given in Table 1.2.
|Buprenorphine||0.01–0.03 mg/kg s.c., i.m., i.v. every 8–12 h|
|Butorphanol||0.1–0.5 mg/kg s.c., i.m. or i.v. every 2–4 h|
|Carprofen||1.0–2.0 mg/kg s.c., i.m. every 12–24 h|
|Ketoprofen||1.0 mg/kg s.c., i.m. every 12–24 h|
|Meloxicam||0.1–0.3 mg/kg s.c. or p.o. every 24 h|
|Morphine||0.5–5.0 mg/kg s.c., i.m. every 2–6 h|
|Pethidine||5–10 mg/kg s.c., i.m., i.v. every 2–4 h|
|Nalbuphine||0.5–1.5 mg/kg i.m., i.v. every 2–3 h|
Ferrets have a very short gut transit time of around 3 h, therefore if starved overnight there is a high risk of hypoglycaemia. Therefore, do not starve preoperatively.
There are many anaesthetic protocols written up in the literature. The author has found the following protocols useful:
Scaling and crusting
Erosions and ulceration
Nodules and non-healing wounds
Changes in pigmentation
Findings on clinical examination
Respiratory tract disorders
Ferrets constantly investigate and monitor their environment by sniffing all available surfaces, hence sneezing is not uncommon.
Findings on clinical examination
Gastrointestinal tract disorders
The permanent incisors erupt at around 6–8 weeks while the other permanents are usually through by 10 weeks.