Treating Fennec Foxes

The fennec fox (Vulpes zerda) has many attributes that could allow it to become a mainstay in exotic animal practice.  These engaging little canids are clean, social, and relatively easy to care for.  As with other exotics, many of the problems encountered with fennecs appear to be husbandry-related.

Classification and Terminology

Foxes are in the Order Carnivora and the Family Canidae.  Worldwide, there are considered to be three separate lineages of “fox-like” canids:

1)     Genus Urocyon (Gray foxes)  and Genus Otocyon (Bat-eared fox)

2)     Genus Dusicyon (“zorros” such as Crab-eating fox, Small-eared fox, and 6 other species)

3)     Genus Vulpes (red fox, fennec fox, arctic fox, and 9 other species)

Formerly, the fennec was classified as a separate genus (Fennecus) due to its rounded skull and weak dentition (1).  Female foxes are referred as vixens, males as reynards, and offspring as kits.  A group of foxes may be referred to as a “skulk” or a “leash”.

Geographic Range and Habitat

Fennecs are found in the Sahara desert region of North Africa, from Morocco and Niger to Egypt and Sudan.  Two reports have been recorded from the Middle East, one from Kuwait, the other from the Sinai (2).  In these desert and sub-desert habitats, fennecs are usually found in sandy areas, where they occupy a permanent den several meters long which they dig themselves. They dig so rapidly they have earned a reputation for being able to sink into the earth.

Fennec foxes are on Appendix II of CITES and considered threatened in the wild.

Anatomy and Physiology

The fennec fox is the smallest wild canid, measuring 20 cm (8 in) at the shoulder and weighing 1-1.5 kg (2-3 lb).  They have the largest ears relative to body size in the dog family, measuring up to 15 cm (6 in) in length.  Fennecs have a soft, thick coat.  Coloration of upper parts is reddish cream or fawn, the underbody is white, and the tail tip is black.  They are fastidiously clean and, unlike other foxes, they have no odor.

The heavily furred tail (sometimes referred to as a “sweep”) helps the fox to change direction quickly, and keeps the fox’s nose and feet warm when it curls up to sleep.  The caudal (or “violet”) gland is covered in bristles and appears as a black spot proximally on the tail of all vulpine foxes.  Its function is unknown.  Foxes have three pairs of mammary glands.  They have paired anal sacs on either side of the anus.  These coat feces with scent and can be evacuated voluntarily.  There are also glands located between the toes.  Their feet are covered with fur, protecting the soles from heat and enabling the fennec to run in loose sand.

Fennecs have exceedingly large tympanic bullae, emphasizing their dependence on hearing for predation.  The fennec fox has the same dental formula as the domestic dog (I3/3, C1/1, PM4/4, M2/3).  Compared with other vulpines, their canines are reduced and their teeth are sharply cuspidate, which may facilitate insectivory (2).  The tapetum lucidum is well developed, and the pupil is eliptical.

Fennec foxes exhibit many unique physiological adaptations to desert life.  Fennec metabolism functions at only 67% of the rate predicted for an animal its size.  Similarly, resting heart rate is only 118 bpm, which is 40% lower than could be expected.  Normal body temperature is 38.2˚C (100.8˚F).  Fennec foxes will shiver when the ambient temperature drops below 20˚C (68˚F).  As air temperature rises, the fennec radiates body heat by dilating blood vessels in its feet and large, vascular ears.

The fennec lets its body temperature rise to 40.9˚C (105.6˚F) before beginning to sweat, reducing water loss.  When it pants it curls its tongue so that saliva is not wasted.  Respiratory rate at rest is 23 breaths/min.  Fennec foxes start to pant only when temperature exceeds 35˚C (95˚F), and jaws open to a full pant only at 38˚C (100˚F).  Panting rates of up to 690 breaths/min have been observed (1).  Although fennec foxes will drink freely when opportunities arise, laboratory studies suggest that fennecs can survive indefinitely without access to free water (2,3).

Reproduction and Longevity

Fennecs are unusual among wild canids in that the female is seasonally polyestrous (2,4).  If the first litter is lost, a second may be produced 2.5-3 months later.  Breeding pairs are monogamous, and will peacefully coexist year round.  In captivity, mating occurs during January and February.  Males urine-mark their territory during this period, and females may develop dorsolateral alopecia (8).  The female is in heat for 1-2 days.  Mating concludes with a copulatory tie that normally lasts up to two hours.  Gestation period is about 51 days (range: 49-63).   

Fennecs become very nervous and aggressive during breeding and rearing.  To prevent neonatal deaths, avoid disturbances until the kits reach 3-4 weeks of age.  There are usually 2-5 offspring in a litter.  Kits open their eyes at 12-14 days.   The reynard remains with his mate after she gives birth, feeding her and protecting the den.  The vixen does not allow him to interact with the kits until they are 5-6 weeks old.  Parent-raised offspring are weaned by 8-10 weeks of age.   In practice, kits are sometimes pulled at 10-12 days, and hand-raised on a fox milk replacer such as Day One® Formula 35/32 (Fox Valley Animal Nutrition).  For hand raised kits, solid food may be introduced at about 1 month, and weaning can occur as early as 6 weeks.  Fennec foxes attain adult size and sexual maturity by 9-11 months.  Lifespan is 12-16 years.

Behavior

Fennec foxes are more social than other fox species.  Though they hunt alone, fennecs live in colonies of up to 10 individuals.  When approached by someone, a fennec will normally cower, lay on his side, yelp, and wag his tail in a submissive manner.  When fennecs are content, purring may be observed (2,4).  They can be taught to fetch, which provides exercise.

Husbandry

Fennecs should be kenneled while unsupervised.  A large ferret or cat cage with shelves makes a suitable crate.  Fennec foxes can easily climb out of fenced enclosures.  Keep humidity down, provide good ventilation, and avoid dusty cage substrates.    

In the wild, fennecs practice site-specific defecation and, therefore, can be litter box trained.  Because of their digging habits, a covered litter box is recommended.  Regular clay litter is best.

They can be leash or harness trained, but will easily escape from either if startled.  A crate is better if going out among strangers.

While fennecs are primarily nocturnal, they also enjoy basking in the sun.

Diet

The diet of fennecs in the wild includes plant material, fruits, small rodents (gerbils, jerboas), birds, eggs, lizards, and insects (locusts).  Digging for plant roots (tubers, bulbs) is one important source of moisture.

In captivity, Mazuri Exotic Canine Diet is widely utilized for this species.   Other food items include high-quality dry dog or cat food, canned dog or cat food, vegetables, fruits, pinkie mice, rodents, eggs, crickets, and mealworms.  Raw meat such as Nebraska Bird of Prey can also be fed, however, fox owners report that this imparts an unpleasant odor to the urine.  Fresh water should be provided at all times.

Preventive Care

  • Annual physical examination
  • Fecal exam for internal parasites
  • Rabies vaccination (IMRAB/Merial)
  • Canine distemper virus and canine parvovirus vaccination (Recombitek/Merial)
  • Flea control (Advantage/Bayer)
  • Canine heartworm preventative
  • Discuss diet and husbandry

Blood collection

Jugular vein, cephalic vein, lateral saphenous

Restraint

Use same methods of restraint as for canines.

Anesthesia

Induction with ketamine 5.5 mg/kg + diazepam 0.28 mg/kg IV

Maintenance with isoflurane 

Clinical syndromes

  • Trauma (bite wounds)
  • Neonatal death (nervous mothering)
  • Neoplasia
  • Renal disease
  • Liver disease
  • Cardiomyopathy
  • Pneumonia
  • Dermatitis (mites, otitis)
  • Fleas
  • Conjunctivitis
  • Corneal lesions (foreign body)
  • Glaucoma
  • Histoplasmosis

Zoonotic potential

  • Tuberculosis
  • Rabies
  • Leishmania

Fennec Fox Products

Day One® Formula 35/32

Fox Valley Animal Nutrition, Inc.

PO Box 146

Lake Zurich, IL 60047

800.679.4666

www.foxvalleynutrition.com

Mazuri Exotic Canine Diet (#5M52)

Mazuri/Purina Mills, Inc.

1401 S. Hanley Rd.

St. Louise, MO 63144

800.227.8941

www.mazuri.com

Nebraska Exotic Carnivore Diets

Central Nebraska Packing, Inc.

P.O. Box 550

North Platte, NE 69103-0550

877.900.3003
www.nebraskabrand.com

References:

  1. Macdonald D (ed): The Encyclopedia of Animals. Oxfordshire, Barnes and Noble Books/Andromeda Oxford Ltd., UK , p54-61, 2001.
  2. Sheldon JW: Wild Dogs: The natural history of the nondomestic Canidae. New York, Academic Press, Inc., p91-95, 1992.
  3. Nowak RM (ed): Walker’s Mammals of the World 5th Ed, Vol. II. Baltimore/London, Johns Hopkins University Press, p1054-1055, 1991.
  4. Alderton, D: Foxes, Wolves & Wild Dogs of the World. New York, Sterling Publishing Co., Inc., p144-146, 1999.
  5. Montali, RJ et al: Clinical trials with canine distemper vaccines in exotic carnivores, JAVMA, Vol 183, No. 11, Dec 1, 1983, p1163-1167.
  6. Himes, EM et al: Tuberculosis in fennec foxes, JAVMA, Vol 177, No. 9, Nov 1,1980, p825-826.
  7. Bekoff M: Social behavior and ecology of the African Canidae: a review, In Fox MW (ed): The Wild Canids. Malabar, Florida, Krieger Publishing Company, Inc., p123-125.
  8. Nutrient Requirements of Mink and Foxes, 2nd. Ed , Nutrient Requirements of Domestic Animals Series , No. 7. Washington DC, National Academy Press, 1983.
  9. Johnson D. Introduction to Fennec Foxes, Exotic DVM, (2003), 5.4:42-45