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A guide to medicine and surgery in sugar gliders

 

GEOFFREY W. PYE, BVSc, MSc*

JAMES W. CARPENTER, MS, DVM, Dipl. ACZM

Exotic Animal. Wildlife, and Zoo Animal Medicine Service

Department of Clinical Sciences College of Veterinary Medicine Kansas State University Manhattan, KS 66506

*Current address: Wildlife and Zoological Medicine Service Department of Small Animal Clinical Sciences College of Veterinary Medicine University of Florida Gainesville, LL 32610-0126

SUGAR GLIDERS are becoming popular pets in the United States because they are cute and docile (if frequently handled).

The family tree

Sugar gliders are marsupials belonging to the superfamily Phalangeroidea (gliders and possums), which is divided into six families. The sugar glider is in the family Petauridae, which comprises striped possums (Dactylopsila trivirgata), Leadbeater's possums (Gymnobelideus leadbeateri), and wristwinged gliders (Petaurus species). There are seven species in the genus Petaurus, of which four are found in Australia-sugar gliders (Petaurus breviceps; Figure 1), squirrel gliders (Petaurus norfolcensis), mahogany gliders (Petaurus gracilis), and yellowbellied gliders (Petaurus australis). Sugar gliders, the most widespread and smallest members of the Petaurus species, are arboreal, volant (capable of flight), and nocturnal animals that normally live in eucalyptus forests in northern and eastern Australia and New Guinea. l -'' There are seven subspecies of sugar gliders, of which three (Petaurus breviceps breviceps, Petaurus breviceps longicaudatus, and Petaurus breviceps ariel) are found in Australia.3

Basic anatomy, physiology, and husbandry

Appearance and anatomy

Sugar gliders have a blue-gray coat with a dark stripe extending from the nose over the head to the lower back. The underbelly, chest, and throat are cream to white, and the eyes are ringed by black fur that extends around the ears. The weakly prehensile tail is covered with thick fur and is about 19 cm long, which is equal to or slightly longer than the head and body length together (Table 1).4 Sugar gliders are noted for the membrane, or patagium, that extends from outside the tip of the fifth finger to inside the first toe on each side (Figure 2). This membrane enables them to glide (volplane) distances up to at least 50 m.3 Each foot has five digits, and all are clawed, except the medial opposable large toe on each hind foot. The second and third digits of each hind foot are partially fused (syndactylous) and form a grooming comb. Sugar gliders do not have the ossa marsupialia or eupubic bones (located off the pelvic region for support of the pouch) characteristic of other marsupials.

Sugar gliders have many scent glands used for marking. The main scent glands are the frontal (found on the forehead), the sternal (found on the chest), and the paracloacal (found alongside the cloaca). Scent glands are also located on the surfaces of the paws, corners of the mouth, and inside surfaces of the external ears.

A sugar glider's gender is easily distinguished. Males have a pendulous scrotum located cranial to their bifurcated penis; females have a ventral abdominal pouch that opens forward. Both sexes have a cloaca into which the reproductive, urinary, and gastrointestinal tracts all open. The reproductive tracts of sugar gliders are typical of marsupials and are described in detail below. Sugar gliders possess an enlarged cecum that may assist in digesting gum from acacia trees.'

Finally, sugar gliders have avascular retinae, with only a small residual tuft of fluoresceinimpermeable vessels projecting from the optic disk into the vitreous, suggesting superior night vision.

Behavior, reproduction, and physiology

In the wild, sugar gliders typically are gregarious and live in groups of up to seven animals, with a male to female ratio of 3:4. Usually only one dominant male breeds, and all females reproduce.'

Scent marking is used to mark specific trees in a territory and also members of a family group. Typically, the dominant male marks the other members in the group with its scent; those not marked are attacked.

Family groups live in tree hollows in the wild and are vocal, communicating through a series of yaps, chatterings, and screams. They chew large holes in the bark of eucalyptus trees to get at the sap and then defend the trees from other sugar-glider groups. Predators in the wild include owls, foxes, cats, kookaburras, and lace monitors.

Females are seasonally polyestrus, while males remain spermatogenic year-round. In Australia, sugar gliders normally mate in June or July but occasionally mate as late as November. Most young are born between August and November. In captivity, there appears to be no definite breeding season.9 Either one (19%) or two (81%) young are born, even though females have four teats in the pouch. As with all marsupials, sugar glider reproduction is characterized by a short gestation period (15 to 17 days) and a much longer development period within the pouch (pouch emergence at 60 to 70 days). Because of this short gestation period, juvenile sugar gliders weigh less than 0.2 g when born and measure about 5 mm in length. Females return to estrus 12 days after the young are removed from the pouch, and the birth of two litters per season is common in the wild. Juveniles usually reach their adult weight within 12 months. Sexual maturity is reached at 8 to 12 months in females and 12 to 15 months in males. Adult males are generally larger than females, but females typically live longer in the wild. In captivity, sugar gliders may live up to 15 years. Physiologic characteristics of sugar gliders are listed in Table 1.

Housing

Sugar gliders should not be kept as solitary animals. A 2-x-2-x-2-m aviary-type cage is suitable for housing up to six sugar gliders. A 50-x50-x-75-cm cage is suitable for two sugar gliders. Wire openings should be less than 2 x 2 cm, or, if there are no cross bars, the vertical bars should be no more than 6 mm apart." owners should avoid using zinc-containing wire because it is potentially toxic if consumed. Advise the owners to include tree branches to allow three dimensional use of the cage space. They should also provide a 25-cm diameter exercise wheel in an elevated position . Make sure the wheel is constructed so the animal's long tail will not be caught (i.e. a solid wheel, not one made of wires).

Because wild sugar gliders normally spend the day in leafy nests constructed in tree hollows, either a hollow log or a small wooden box should be provided for nesting. A 25-x-10-x-15-cm nest box will easily accommodate six sugar gliders. Group size in captivity may be limited by the size of the nest box . A box with a hinged lid makes it easier to catch an animal for examination. The nest box should be well-secured in an elevated position and have a 5-cm diameter opening. Keep in mind that sugar gliders will chew wooden structures, which may allow them to escape.

No bedding needs to be supplied for nest boxes, but a piece of cloth or a sock can be provided for comfort. Advise owners to avoid using newspaper and cedar or pine shavings for bedding because of inks and aromatic oils that can be toxic. Owners should also clean the nest box on a regular basis. Sugar gliders are often kept at temperatures between 64 and 75 F (18 to 24 C), but this is at the low end of their comfort level so a supplementary heat source should be provided. They can cope with temperatures up to 88 F (31 C), but above this they will have difficulty controlling their body temperature and may suffer from hyperthermia.

 

Table1

Average life span

Male (wild)

4 years (maximum 5)

Female (wild)

5 years (maximum 7)

Maximum reported life span

(captive)

15 years

Average adult weight

Male

115-160 g (average 140 g)

Female

95-135 g (average 115 g)

Body length

16-21 cm (average 17 cm)

Tail length

16.5-21 cm (average 19 cm)

Heart rate

200-300 beats/min

Respiratory rate

16-40 breaths/min

Rectal temperature

97.2 ± 0.7 F (36.2 -+ 0.4

Basal metabolic rate

2.54 W kg

Estrous cycle

Type

Seasonally polyestrus

Length

29 days

Gestation period

15-17 days

Litter size

1-2 (usually 2)

Birth weight

0.19 g

Pouch emergence

60-70 days

Weaning age

110-120 days

Sexual maturity

8-15 months

Table 2

Dietary Components for Sugar Gliders in Captivity

Fruit

Oranges, watermelons, pawpaw, pears, kiwi, apricots, berries, bananas, apples,

mangoes, grapes, melons, and figs

Invertebrates

Mealworms, grasshoppers, moths, fly pupae, and crickets

Blossoms and branches

Eucalyptus, Banksia, Leptospermum, Grevillea, Acacia, Melaleuca. Callistemum, and Hakea species

Supplements

Sugar glider pellets or insectivore diets, nectar mix, vitamins, and minerals

Table 3

Suggested Sugar Glider Diet

Items (mixed into a slurry)

Diet by Weight (%)

Amount for One Adult Animal (g)

Chopped, mixed fruit**

40

12

Cooked. chopped vegetables`

8

2.5

Peach or apricot nectar

34

10

Ground, dry, low-iron bird diets

18

5.5

Total

100

30

Nutrition

in the wild, sugar gliders eat arthropods, Acacia species gum, Eucalyptus species phloem sap, nectar and pollen, manna (sap oozing from wounds on trees produced by other sap-sucking animals), and honeydew (the exudate produced by some sapsucking insects). Seasonal variance occurs, with plant exudates making up most of the diet in autumn and winter and invertebrates in spring and summer.

In captivity, sugar gliders have been reported to capture and consume house mice. Diets consisting of a variety of fruits, a commercial monkey diet (Mazuri® primate diets-Purina Mills) or bird pellets, crickets and mealworms, and vitamin and mineral supplements have been used with success (Tables 2 3). A source of protein appears to be essential for breeding and lactation. Sugar glider pellets and insectivore diets are now available and are a better alternative to a commercial monkey diet or bird pellets.

Fresh water should always be provided and changed at least daily. Sugar gliders can drink from sipper bottles. Artificial nectar or fresh or canned nectar and juices can be used daily. Fresh food should be offered daily at a maximum of 15% to 25% of the sugar glider's body weight. A pinch of a calcium supplement (Phosphorus-Free Calcium with Vit. D3 powder-Rep-Calms Research Labs, Los Gatos, Calif.; (800) 406-6446; www.repcal.com) and a multivitamin and mineral supplement (HerptiviteTM-Rep-Cal® Research Labs) mixed in the food can be used to prevent nutritional diseases. Because sugar gliders prefer to eat in a high place, food and water bowls should be placed in an elevated position and not on the cage floor.

Hand-raising orphans

Hand-raising orphaned sugar gliders can be difficult. Success rates in raising furless young (< 60 days old) are low unless they are raised by experienced hand-raisers. Success rates in rearing furred young, however, are much higher.' A cotton sock or sweatshirt can be used as a substitute pouch. Marsupials are born without the ability to control body temperature, so warmth needs to be provided.' Furred young require a temperature range of 86 to 93 F (30 to 34 C), which can slowly be lowered to room temperature as they develop (up to 100 days). Unfurred young need to be fed low lactose milk every one to two hours; furred young should be fed this milk every four hours (Table 4). To feed young sugar gliders, attach a small, soft catheter cut short to a syringe. When a little older, sugar gliders can be fed with a small doll's bottle that has a nipple. Monitor the juvenile's development by weighing it on a regular basis . Growth and development can also be correlated with age (Table 4). The owners should encourage the animal to defecate and urinate after each feeding by gently wiping the cloaca with moistened cotton wool. The young can be offered solid foods at about 3 months of age and can be fully weaned by 4 months.

Handling

To manually restrain a sugar glider, hold its head between your thumb and middle finger, place your index finger on top of its head, and palm the rest of the animal. Alternatively, a small cloth bag can be placed over your hand (seams inside). The animal can then be palmed and the bag pulled off your hand and over the animal (seams outside to avoid entangling the animal in the frayed edges). Once in the bag, the animal can be weighed. Exposure of the head from the bag allows you to place a facemask for anesthetic induction.

 

Table 4 Growth and Development of Sugar Gliders

Age (days)

Weight (g)

Feed (ml/day)

Developmental Characteristics

1

0.2

Mouth and forelimbs must developed features

20

0.8

Ears free from head, papillae of mystacial vibrissae (whiskers) visible

35

2

1

Mystacial vibrissae erupt, ears pigmented

40

3

1.5

Pigment an shoulders begins to appear, eye slits present

60

12

3

Detaching from teat, fur emerges, dorsal stripe develops

70

20

4

Eyes open, fully furred, left alone in nest

80

35

6

Fur lengthens

90

44

7

100

54

8

Emerging from nest, starts eating solids (Table 3)

130

78

See Table 3

Weaned

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