Ferrets

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.

Table 1.1 The ferret: Key facts

Average life span (years)		5–8+
Weight (kg) Male		1.0–2.0 kg
	Female	0.5–1.0 kg
Body temperature (°C)		37.8–40
Respiratory rate (per min)		33–36
Heart rate (beats/min)		180–250
Gestation (days)		41–42
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.

Blood sampling

Suitable sites for venepuncture are the jugular, cephalic and saphenous veins. Alternatively, the ventral tail artery and veins can be used.

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.

Nursing care

Thermoregulation

For general principles, see Thermoregulation under ‘Nursing Care’, in Ch. 2, Rabbits.

Fluid therapy

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.

Blood transfusions

Blood volume is 40–60 mL per ferret. Blood groups have not been demonstrated (Manning & Bell 1990), so there is thought to be no need for cross-matching.

Estimation of blood volume requirement

Based upon an assumption of 70 mL/kg per h maintenance fluid requirement (Orcutt 1998):

Analgesia

Analgesic doses for ferrets are given in Table 1.2.

Table 1.2 The ferret: Analgesic doses

Analgesic	Dose
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

Anaesthesia

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:

• Intraoperative care

• Keep warm (see Thermoregulation)

• Fluids (see Fluid Therapy)

Skin disorders

• Ferrets under a seasonal cycle of hair thinning occurring during the summer months. There are multiple sebaceous glands in the skin that impart both a greasy feel to the coat and the typical musky ferret smell. These glands are more numerous in males, and in some albino males they can produce a dirty, yellow appearance. Routine neutering causes some atrophy of these glands reducing the odour.

Scaling and crusting

• Canine distemper virus (CDV) (see Systemic Disorders)

• Dermatophytosis.

Erosions and ulceration

• Excoriation from self-inflicted trauma if pruritic

• Blastomyces dermatitidis

• Cryptococcus bacillisporus.

Treatment/specific therapy

• Commercial flea treatments at cat dose rates

• Lufenuron at 10 mg/kg s.c. or 30 mg/kg p.o. in food

• Topical spot on preparations of 10% (w/v) imidacloprid (Advantage, Bayer) at 10 mg/kg and 10% (w/v) imidacloprid/50% (w/v) permethrin (Advantix, Bayer) at 10 mg/kg have proven efficacious at flea control on the mink (Larsen et al 2005) and should be safe on the ferret. Environmental flea control will be required

• Sarcoptic mange

• Ivermectin at 0.2–0.4 mg/kg s.c. every 7–14 days to resolution

• Selamectin at dose for ear mites (see Ear mites below)

• Moxidectin at dose for ear mites (see Ear mites below)

• Topical antiparasitic ear preparations, although the small size of the ear canal may prevent effective treatment

• Selamectin spot-on at 6 mg/kg as a topical spot-on preparation; has proven safe at 45 mg /adult ferret (Stronghold Cat, Pfizer) (Miller et al 2006)

• 10% imidacloprid/1% moxidectin (Advocate, Bayer) at 1 drop per 100 g bodyweight (Beck 2007)

• Cross infection with dogs and cats in the same household may occur

• Removal of larvae

• Clean and debride wounds

• Systemic parasiticide, e.g. ivermectin, selectin, imidacloprid

• Covering antibiosis

• Supportive therapy if necessary

• Pyoderma, bacterial dermatitis and cellulitis

• Shave any badly infected areas

• Topical and parenteral antibiotics

• Cleaning with chlorhexidine solution may be beneficial

• Surgical removal of abscesses

• Bites and lacerations

• Clean and debride well

• Covering broad-spectrum antibiosis

• Actinomycosis

• Debride and clean lesion

• Appropriate antibiosis

• Cryptococcus

• Amphotericin B at 150 mg/kg i.v. 3 times weekly for 2–4 months

• Seasonal alopecia

• In breeding season (March to August). Will regrow

• Hair loss occurring in winter and early spring may be an early indicator of hyperadrenocortism (see Endocrine Disorders)

• Self-mutilation

• Lack of suitable hiding places or other stressors

• Females plucking hair for nesting

• Biotin deficiency

• Associated with diets >10% raw egg

• Reduce egg intake and supplement with proprietary vitamin formula

• Aggressive surgical resection

• Chemotherapy may be attempted. Accessible cutaneous tumours can be treated by injecting cisplatin directly into the tissue mass on a weekly basis as a debulking exercise.

Respiratory tract disorders

Ferrets constantly investigate and monitor their environment by sniffing all available surfaces, hence sneezing is not uncommon.

Treatment/specific therapy

• Canine distemper virus (see Systemic Disorders)

• Bacterial pneumonia

• Appropriate antibiosis

• Otherwise care as described under Management

• Mycobacteriosis

• Potential zoonosis so consider euthanasia

• M. abscessus has been successfully treated with clarithromycin (Lunn et al 2005)

• Fungal mycoses

• Ketoconazole at 10–30 mg/kg p.o. s.i.d. for 60 days.

• Amphotericin B

• 0.25–1.0 mg/kg i.v. s.i.d. or every other day until a total dose of 7–25 mg has been given

• For Cryptococcus, 150 mg/kg i.v. 3 times weekly for 2–4 months

• Itraconazole at 25–33 mg/kg p.o. s.i.d. long term

• Pneumocystis carinii

• Pentamidine isethionate at 3–4 mg/kg on alternate days for a maximum of 10 treatments

• Trimethoprim-sulfamethoxazole at 30 mg/kg p.o., s.c. b.i.d.

Gastrointestinal tract disorders

Permanent dental formula of the ferret

The permanent incisors erupt at around 6–8 weeks while the other permanents are usually through by 10 weeks.

Deciduous dental formula of the ferret

Disorders of the oral cavity

• Salivary mucocoele

• Facial swellings

• Aspirate sample for analysis including cytology (differentiate from abscess, neoplasia, haematoma)

• Surgical resection of the affected gland is best option to prevent recurrence. Zygomatic and buccal glands commonly affected – may require removal of zygomatic arch to aid surgical resection (Mullen 1997)

Differential diagnoses for gastrointestinal disorders

Viral

• Canine distemper virus (CDV) (see Systemic Disorders)

• Influenza virus (transient diarrhoea)

• Epizootic catarrhal enteritis (green slime disease) (coronavirus).

Fungal

• Cryptococcus neoformans var grubii (Malik et al 2002).

Protozoal

• Cryptosporidium.

Parasitic

• Toxascaris (uncommon)

• Toxocara (uncommon)

• Ancyclostoma (uncommon)

• Cestodes (uncommon).

Nutritional

Neoplasia

• Lymphoma/lymphosarcoma (see Systemic Disorders)

• Adenocarcinoma

• Anal gland neoplasia.

Findings on clinical examination

• Diarrhoea (with or without blood/melaena). For melaena, see also Urinary Tract Disorders)

• Green diarrhoea (epizootic catarrhal enteritis, Hepatic Disorders)

• Vomiting/gagging

• Dehydration

• Hypersalivation

• Teeth grinding and abdominal pain

• Weight loss

• Gastric distension, dyspnoea, cyanosis

• Haemorrhagic diarrhoea in young ferrets. Occasional rectal prolapse (Isospora)

• Faecal tenesmus (especially in ferrets under 1 year of age) (PBD)

• Thickened bowel palpable (PBD, EGE)

• Colitis-like signs – increased amount of mucous and frank blood in the stool (PBD, EGE)

• Vomiting (± blood from erosions or ulcers), black tarry diarrhoea (small intestine), watery diarrhoea with frank blood (large intestine) and weight loss (EGE)

• Enlarged mesenteric lymph nodes may be palpable (EGE)

• Palpable foreign body

• Gastrointestinal signs are rare with CDV, but it should be considered if accompanied by oculo-nasal discharge, hyperkeratosis and respiratory signs.

Treatment/specific therapy

a Supportive treatment only

b Usually in young ferrets at 2–6 weeks old

2 Influenza virus (see Respiratory Tract Disorders)

3 Epizootic catarrhal enteritis

a Supportive treatment plus covering antibiotics

4 Bacterial diseases including salmonellosis

a See Management, above

b Appropriate antibiosis

5 Proliferative bowel disease

a Chloramphenicol at 50 mg/kg i.m., s.c., p.o., b.i.d.

b Metronidazole at 20 mg/kg p.o. b.i.d. for 3 weeks

7 Mycobacteriosis

a Potential zoonosis

b Consider euthanasia

8 Cryptococcus

a Amphotericin B at 150 mg/kg i.v. 3 times weekly for 2–4 months

a Sulfadimethoxine at 30 mg/kg b.i.d.

b Amprolium at 100 mg/kg p.o. in food or water daily for 7–10 days

a Metronidazole at 10–20 mg/kg b.i.d. for 10 days

Tags: Exotic Animal Medicine A Quick Reference Guide

Aug 21, 2016 | Posted by admin in EXOTIC, WILD, ZOO | Comments Off

Full access? Get Clinical Tree

Get Clinical Tree app for offline access

Get Clinical Tree app for offline access