Ferrets: Domestication and Purpose

Domestic Ferret

• Domestic ferrets (Mustela putorius furo) are derived from European polecats.
• They were believed to be domesticated by Egyptians around 3000 B.C. for rabbit hunting.
• Domestic ferrets arrived in North America with early settlers in 1875.

European Polecat

• European polecats are not closely related to black-footed ferrets (Mustela nigripes), the only native ferret species in North America.

Legal Issues

• Ferrets are not recognized as domestic animals in parts of the USA and are illegal as pets in some states and Japan.
• Some states require a permit to own and/or breed ferrets.

Anatomy & Physiology

Body Shape

• Ferrets have a long, thin, and tubular body shape with short legs.
• They have a very flexible spine and a neck almost as wide as their mandible.
• Their feet have long claws for digging.

Weight

• Intact males (hobs) weigh 1-2 kg, while intact females (jills) weigh 0.5-1 kg.
• Females can grow larger if spayed before sexual maturity.
• Ferrets experience seasonal weight changes, with a 30-40% increase in fall and a decrease in spring/summer.

Hair Coat

• The normal coat color is sable (fitch).
• There are over 30 recognized color mutations, including albino, cinnamon, silver mitt, Siamese, panda, butterscotch, and chocolate.
• Ferrets shed in spring and regrow their coat in fall.

Skin

• Ferrets have no sweat glands, only sebaceous (oil) glands.
• They have anal glands that produce a powerful odor.

Skeletal System

• Ferrets have a skull and muscles developed for strength and shearing action.
• Their vertebral formula and large cervical vertebrae provide stability when capturing and subduing prey.
• Their feet have 5 digits with non-retractable claws.
• Os penis (J-shaped) is present in males.

Digestive System

• Ferrets have 34 teeth, with a dental formula of I 3/3, C1/1, P3/3, M1/2.
• Canines have a long crown and root, making extraction difficult.
• Premolars and molars (except molar 2) have multiple roots.
• The gastrointestinal tract has a simple stomach that expands greatly and can vomit or regurgitate.
• The short small intestine (182-198 cm) and large intestine (10 cm) have a short GI transit time (3-4 hours).
• There is no cecum or ileocolic valve.

Cardiovascular System

• The heart is located between the 6th and 8th ribs.
• A single central artery (innominate artery I or brachiocephalic artery) is present instead of bilateral carotid arteries.
• This may be an adaptation for maintaining blood flow to the brain when turning the head 180 degrees.

Respiratory System

• The trachea is long, with 60-70 large diameter rings.
• The lungs have 6 lobes (4 right and 2 left).
• Ferrets have decreased central airway and pulmonary resistance, with a large respiratory reserve.

Spleen

• The spleen is located along the greater curvature of the stomach and is attached to the stomach and liver by the gastrosplenic ligament.
• It is crescent-shaped and varies in size depending on age and health.

Reproduction

• The natural breeding season for males is December to July, and for females, it is March to August.
• Females are seasonally polyestrus, with the onset of estrus coinciding with increasing day length.
• Induced ovulators (30-40 hours after copulation) have a gestation period of 41-43 days.
• If bred but not pregnant, females can experience pseudopregnancy lasting 40-42 days.
• If not bred, around 50% of females will remain in estrus, leading to bone marrow toxicity due to elevated estrogen levels.

Ferret Behavior and Husbandry

• Ferrets are active and inquisitive animals that are social but have no well-defined social structure.
• Estrus females and intact males may fight, but they can get along with dogs and cats.
• However, they should not be trusted with birds, rodents, or rabbits.
• Ferrets are relatively quiet, making low-pitched mumbling, chuckling (dooking), hissing, and screaming sounds.
• They are capable of using a litter box and exhibit latrining behavior.

Ferret Proofing

• Seal all holes and openings wider than 1 inch to prevent escape and injury.
• Close cabinets and dishwasher to prevent access to hazardous items.
• Remove access to soft rubber and plastic items to prevent ingestion and GI obstruction.

Housing

• Ferrets require a minimum cage size of 24” x 24” x 18” with adequate ventilation (wire cages are best).
• The cage should provide vertical space and be at least "2 ferrets" long and deep.
• Complete shelves, solid-bottomed sleeping box or hammock, and a litter box are essential.

Outdoor Housing

• Ferrets cannot tolerate temperatures above 90°F and require shade to prevent hyperthermia and heat prostration.
• Provide a heat source in temperatures less than 20°F.
• Protect ferrets from predators and provide heartworm preventative measures.

Vaccines

• Rabies Virus vaccination is required annually, using a vaccine approved for ferrets.
• Canine Distemper Virus vaccination is also required annually, but cannot use the same vaccine used in dogs.
• Ferrets are not susceptible to Feline Panleukopenia Virus or Feline Viral Rhinotracheitis.

Vaccine Reactions

• Vaccine reactions are common in ferrets and occur within an hour after vaccination.
• Clinical signs of anaphylaxis include generalized hyperemia, ptyalism, vomiting, and piloerection of the hair on the body and tail.

Nutrition

• Ferrets are strict carnivores and require a diet rich in protein and fat.

Ferret Restraint

• Simple hold involves holding the ferret by scruffing the nape of the neck
• Scruffing the neck and holding around the waist is an alternative method
• Ferrets may object to mildly invasive procedures and can bite if necessary

Clinical Techniques

• Ultrasound, ear swab, and nail trim are common procedures
• Head control and scruffing are essential techniques for ferret restrains

Drug Therapy

• IV administration is recommended for very ill animals
• IM administration is a good route, but has limited muscle mass
• SC administration is the preferred parenteral route in most cases
• PO administration is suitable for palatable liquids, but difficult for non-palatable liquids and pills

Giving Oral Medications

• Oral medications can be challenging to administer

Venipuncture

• Large sample sites include the jugular vein, cranial vena cava, and ventral tail artery
• Smaller sample sites include the lateral saphenous vein and cephalic vein
• Gauge sizes and sample volumes vary depending on the site

Intravenous Catheter

• Lateral saphenous and cephalic veins are suitable for catheter placement
• Sedation or anesthesia is recommended for catheter placement
• Possible complications include overhydration, entanglement, and chewing the line

Fluid Therapy

• Routes of administration include SC and IV
• SC administration involves dividing the calculated volume into 2-3 sessions throughout the day
• IV administration requires an infusion pump and a pediatric drip set

Blood Transfusion

• Consider blood transfusion if the PCV is 15 or less
• Ferrets may tolerate a PCV of 12% without transfusion if anemia is chronic
• There are no detectable blood groups in ferrets
• The best donor is a large male ferret, which can safely donate 6-10 ml of blood

Ferret Diseases

Gastrointestinal Diseases

• Dental Disease:
  • Fractured Canine Teeth: common, can be smoothed off with Dremel tool if not into the pulp cavity, otherwise requires root canal or extraction
  • Dental Calculus (tartar) build-up: leads to Gingivitis & Periodontitis, common in ferrets > 1 yr old, especially if fed soft or canned foods
  • Tooth Root Abscess: occasional, check for chronic tearing, may require anesthesia and probing
• GI Foreign Body (GI FB):
  • Common, especially in ferrets < 2 yrs old, often ingested rubber or other objects
  • Clinical Signs: variable, acute or chronic, may have depression, anorexia, dehydration, absence of stools, nausea, vomiting, and GI bleeding
  • Diagnosis: palpation of gas and fluid in stomach and/or intestines, may require barium series or exploratory surgery
  • Treatment: Surgery, supportive care with fluids and antibiotics
• Gastroenteritis / GI Ulcers:
  • Causes: FB/trichobezoar, Helicobacter mustelae infection, Viral, Ulcerogenic drugs, GI neoplasia, Inflammatory Bowel Disease, Psychologic stress
  • Clinical Signs: ptyalism, bruxism, vomiting, diarrhea, weight loss
  • Gastritis: significant cause of morbidity and mortality in ferrets

Hematopoietic Diseases

• Aplastic Anemia: secondary to hyperestrogenism
• Splenomegaly
• Lymphosarcoma

Urogenital Diseases

• Chronic Interstitial Nephritis: common, especially in older ferrets
• Urinary Tract Infection / Pyelonephritis: common in females
• Dysuria & Urethral Obstruction: secondary to Prostatic Enlargement & Cysts, common in males
• Urolithiasis (Renal / Bladder Stones): uncommon

Viral Diseases

• Epizootic Catarrhal Enteritis (ECE) = Coronavirus infection = “Green Slime Disease”:
  • Causes: Coronavirus, high morbidity and mortality in kits 2-6 wks old
  • Clinical Signs: watery, dark green, foul-smelling diarrhea, anorexia, vomiting, weight loss, dehydration, death
  • Diagnosis: culture of feces during the first 3 days after seeing green diarrhea
  • Treatment: supportive care with fluids and broad-spectrum antibiotics
• Ferret Kit Disease = Rotavirus infection:
  • Causes: Rotavirus, high morbidity and mortality in kits 2-6 wks old
  • Clinical Signs: vomiting, diarrhea, anorexia, weight loss, dehydration
  • Diagnosis: Electron Microscopy (EM), serology is unreliable
  • Treatment: supportive care, treat secondary bacterial infections
• Canine Distemper Virus (CDV):
  • Causes: CDV, accelerated syndrome in ferrets with clinical signs similar to those in dogs
  • Transmission: aerosols, contact with ocular or nasal discharge, urine, feces, saliva, skin lesions, or contaminated fomites
  • Clinical Signs: anorexia, depression, pyrexia, mucopurulent oculonasal discharge, papular rash, skin hyperkeratosis, dermatitis
  • Diagnosis: characteristic clinical signs, fluorescent antibody test, immunohistochemistry, histopathology
  • Treatment: not recommended, usually fatal
  • Prevention: vaccination

Other Diseases

• Influenza Virus:
  • Family Orthomyxoviridae
  • Ferrets susceptible to human influenza