{"id":38917,"date":"2018-06-11T00:19:49","date_gmt":"2018-06-11T05:19:49","guid":{"rendered":"https:\/\/lafeber.com\/vet\/?p=38917"},"modified":"2021-04-27T19:56:02","modified_gmt":"2021-04-28T00:56:02","slug":"basic-information-sheet-virginia-opossum","status":"publish","type":"post","link":"https:\/\/lafeber.com\/vet\/basic-information-sheet-virginia-opossum\/","title":{"rendered":"Basic Information Sheet: Virginia Opossum"},"content":{"rendered":"

Virginia Opossum (Didelphis virginiana<\/em>)<\/h1>\n

\"Virginia<\/p>\n

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Natural history<\/h2>\n

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The Virginia opossum is the only marsupial native to North America. This New World species is correctly called an \u201copossum\u201d as opposed to the Old World \u201cpossum\u201d. 5<\/sup><\/a>,<\/sup>6<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>22<\/sup><\/a>,<\/sup>24<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/p>\n

When Europeans began to settle in North America, the range of this species extended as far north as Ohio and West Virginia. Over time, and with the introduction of the opossum into California in 1910, populations now extend into British Columbia and throughout Central America. The Virginia opossum\u2019s range extends throughout the United States, except in extremely mountainous or arid regions.\u00a02<\/sup><\/a>,<\/sup>4,<\/sup><\/a>5<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>18<\/sup><\/a>,<\/sup>22<\/sup><\/a>,<\/sup>24<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/p>\n

Unlike most wild animals, the opossum flourishes in urban areas, and the presence of human settlements actually serves to increase the opossum\u2019s habitat and population size.\u00a02<\/sup><\/a>,<\/sup>5<\/sup><\/a>,<\/sup>29,<\/sup><\/a>30<\/sup><\/a><\/p>\n

Virginia opossums are often seen as pests and in many states, it is illegal to keep this species as a pet. The opossum is not sold in the pet trade, and animals kept as companion animals or zoological specimens were often orphaned during infancy.\u00a011<\/sup><\/a>,<\/sup>21<\/sup><\/a>,<\/sup>25<\/sup><\/a>,<\/sup>29<\/sup><\/a>
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Conservation status<\/h2>\n

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\nAccording to the International Union for Conservation of Nature Red List<\/a>, the Virginia opossum is a species of least concern with growing and stable populations.\u00a025<\/sup><\/a><\/p>\n

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Taxonomy<\/h2>\n

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Class<\/strong>: Mammalia<\/em><\/p>\n

Subclass<\/strong>: Marsupialia<\/em><\/p>\n

Order<\/strong>: Didelphimorphia<\/em><\/p>\n

Family<\/strong>: Didelphidae<\/em><\/p>\n

Genus<\/strong>: Didelphis<\/em><\/p>\n

Species<\/strong>: virginiana <\/em><\/p>\n

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Physical description<\/h2>\n

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Virginia opossums are medium-sized marsupials with a long and largely hairless, prehensile tail; large, hairless ears; and short, stumpy legs with five toes that include an opposable thumb on both the front and hind feet. Opossums possess a white face, wool-type fur with a whitish undercoat, and guard hairs of varied color.\u00a06<\/sup><\/a>,<\/sup>10<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/p>\n

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Diet<\/h2>\n

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The Virginia opossum is an omnivore. Free-ranging animals consume a varied diet that includes plant material, grasses and leaves, grains, fruits, seeds and bulbs, carrion, snails, slugs, worms, insects, rats, mice, snakes, amphibians, eggs, crayfish, and fish. Opossums are highly opportunistic and a large amount of their diet consists of scavenged food items, like carrion.\u00a05<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>16<\/sup><\/a>,<\/sup>21<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/p>\n

Offer captive opossums a balanced diet consisting of small amounts of a formulated diet (omnivore diet or low fat\/low calorie cat food) supplemented with vegetables, small amounts of fruit (10-20% of the diet), and occasional (once or twice weekly) protein sources.\u00a06<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>22<\/sup><\/a>\u00a0 These sources of protein can include:\u00a0 invertebrates, such as calcium gut-loaded crickets, superworms, or other dusted adult insects, 1 small or medium whole mice, canned salmon, 1 sardine, 1\/2 hard-boiled egg or scrambled egg with the shell, 1 tablespoon yogurt, or cooked chicken liver (Kathy Duncan, written communication to author, July 5, 2018).<\/p>\n

Note: Owners may refer to \u201cPeter\u2019s Food\u201d, an adult opossum diet consisting of 1-part cat food plus 1-part blended vegetables and 0.25%-part non-fat yogurt. 14<\/sup><\/a> \u201cPeter\u2019s Food\u201d was developed for the National Opossum Society<\/a> by Dr. Anita Henness.<\/p>\n

In a rehabilitation setting or home with multiple animals, a diet that can be made up in large quantities<\/a>\u00a0may be preferable. Pacific Wildlife Care has successfully used this diet long term, and it is based on a regimen described by Gode and Ruth (Kathy Duncan, written communication to author, July 5, 2018)<\/small>.\u00a07<\/sup><\/a><\/small><\/p><\/blockquote>\n

As a general rule, metabolism in a marsupial is approximately one-third that of a similarly sized placental mammal. Pairing this slower metabolic rate with the opossum\u2019s voracious appetite, means it is easy to overfeed pet opossums. Owners should carefully monitor and control food intake while encouraging activity to minimize the risk of obesity. 6<\/sup><\/a>,<\/sup>14<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/p>\n

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Housing<\/h2>\n

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Cage design<\/td>\nA modified rabbit or ferret cage is often used for captive opossums. If housed outdoors, know that opossums can dig beneath fences. 11<\/sup><\/a>,<\/sup> 21<\/sup><\/a><\/td>\n<\/tr>\n
Cage size<\/td>\nYoung opossums, whether housed individually or together, require a cage at least 35 cm (1.1 ft.) high and 45 cm (1.5 ft.) wide by 75 cm (2.5 ft.) long.<\/p>\n

Juveniles over 350-400g should ideally be housed in large, outdoor cages, either 4\u2019x4\u2019x 8\u2019 or 4\u2019x 8\u2019x 8\u2019 with branches for climbing (Kathy Duncan, written communication to author, July 5, 2018).<\/p>\n

House adult opossums in \u201cgang yards\u201d at least 30 x 50 m.\u00a011<\/sup><\/a><\/td>\n<\/tr>\n

Cage furniture<\/td>\nVirginia opossums are agile climbers and the enclosure should ideally provide climbing structures. 6<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>21<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/p>\n

Also provide some form of visual security, such as a cardboard or wooden box filled with newspaper pellets, shredded paper, or wood shavings. The nest box should be at least 30 x 45 x 40 cm large.\u00a011<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/p>\n

Opossums tend to select a latrine area and can be trained to use a litter box or newspapers. 6<\/sup><\/a>,<\/sup> 21<\/sup><\/a><\/td>\n<\/tr>\n

Supervision<\/td>\nAlthough owners often allow pet opossums to freely roam the home, constant supervision is recommended as with other exotic pets. Fortunately, opossums do not tend to be destructive although they will attempt to nibble on houseplants.\u00a011<\/sup><\/a>,<\/sup>14<\/sup><\/a>,<\/sup>21<\/sup><\/a><\/td>\n<\/tr>\n
Environmental temperature<\/td>\nThe ideal temperature for housing an opossum is 22\u00b0C (71.6\u00b0F), with an appropriate range of 10-30\u00b0C (50-86\u00b0F).\u00a011<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/td>\n<\/tr>\n
Humidity<\/td>\n> 58% 11<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n


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Activity<\/h2>\n

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\nVirginia opossums are agile climbers. Juveniles use their prehensile tail to swing from branches. Adult opossums are too heavy to support their body weight with the tail, however adults still use their tails to grasp bundles of leaves or bedding material. Opossums are also able to swim, dig, and even run.\u00a06<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>21<\/sup><\/a>,<\/sup>29<\/sup><\/a>
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Behavior<\/h2>\n

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Nocturnal<\/td>\nFree-ranging opossums are nocturnal, however pet animals can adjust to their owner\u2019s diurnal lifestyle.\u00a06<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>21<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/td>\n<\/tr>\n
Social behavior<\/td>\nFree-ranging opossums tend to be solitary animals and are best housed singly in captivity unless the animals were reared together as juveniles. Depending on the wildlife rehabilitation facility, single juveniles weighing less than 100-150 grams are often combined\u00a0(Kathy Duncan, written communication to author, July 5, 2018).<\/p>\n

Adult opossums can display aggression or even cannibalism if housed under crowded conditions.\u00a0Also separate wounded animals, even from littermates, because of the species\u2019 tendency towards cannibalism (Kathy Duncan, written communication to author, July 5, 2018).<\/p>\n

Mating behavior is one of the few social behaviors displayed in the Virginia opossum.<\/td>\n<\/tr>\n

Grooming behavior<\/td>\nOpossums are fastidious groomers.\u00a06<\/sup><\/a>,<\/sup>21<\/sup><\/a><\/td>\n<\/tr>\n
Elimination behavior<\/td>\nOpossums tend to select a latrine area and can be trained to use a litter box or newspapers.\u00a06<\/sup><\/a>,<\/sup>21<\/sup><\/a><\/td>\n<\/tr>\n
Defensive behavior<\/td>\nIf something startles an opossum, its first reaction is to flee to a place of safety, like its cage or nest box. It is also possible for a threatened adult opossum to bare teeth and stand its ground. Normal defensive behavior that can be expected in a recently trapped opossum can include lowering the lip, drooling, growling and hissing, as well as striking and attempting to bite. The animal may empty its paracloacal glands, releasing a noxious odor that resembles death and decay. In addition to hissing, other vocalizations associated with aggression include clicking, growling, and screeching.\u00a011<\/sup><\/a>,<\/sup>21<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/p>\n

\u201cPlaying possum\u201d is a rare defensive catatonic state that occurs in response to a threat most frequently displayed in young opossums. The animal falls over and lies motionless to feign death for as little as 1 minute or up to 6 hours.\u00a011<\/sup><\/a>,<\/sup>29<\/sup><\/a>\u00a0 This collapse is often accompanied by a small release of odiferous glandular material from the paracloacal glands.<\/td>\n<\/tr>\n

Reproductive behavior<\/td>\nThe breeding season varies with the population range, lasting from February to September in Northern climates and between January to August in Southern climates. Free-ranging males roam, searching and vying for reproductive females. Intact female opossums tend to be extremely restless. They will pace and drool on household objects while making a clicking sound. Mating behavior is one of the few social behaviors displayed by the Virginia opossums. During the breeding season, mates may communicate with a series of metallic clicking sounds. After mating, females resume their aggressive, solitary behavior.\u00a011<\/sup><\/a>,<\/sup>14<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/td>\n<\/tr>\n
Parental care<\/td>\nMale opossums provide no parental care. Females with pouch young becomes very protective, frequently licking at the pouch and their offspring. Females maintain auditory contact with their young through a series of clicks, lip smacking, and bird-like sounds. Females show little interest once young leave the pouch. 29<\/sup><\/a><\/td>\n<\/tr>\n
Pet quality<\/td>\nIt is illegal to keep opossums as pets in some jurisdictions, including the state of California. Hand-raised opossums can be comfortable in captivity and bond with their caregiver, however they are relatively high-maintenance pets requiring a great deal of exercise, a special diet, and a significant time commitment from the owner. Opossums in captivity tend to be docile and can respond to their name and other verbal cues.\u00a011<\/sup><\/a>,<\/sup>14<\/sup><\/a>,<\/sup>21<\/sup><\/a>\u00a0 Pet opossums may seek human companionship, climbing into the owner\u2019s lap or onto a shoulder. They may enjoy being stroked or groomed with a small, soft brush.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Normal physiologic data<\/h2>\n

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Lifespan<\/td>\nWild opossums have a relatively short lifespan of approximately 1.5-2 years. Captive opossums normally live between 3-4 years, however up to 8-10 years has been described.\u00a06<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>21<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/td>\n<\/tr>\n
Body weight<\/td>\nAdult female<\/td>\n1.9-2.1 kg 11<\/sup><\/a>,<\/sup> 29<\/sup><\/a><\/td>\n<\/tr>\n
Adult male<\/td>\n2.1-5 kg 11<\/sup><\/a>,<\/sup> 29<\/sup><\/a><\/td>\n<\/tr>\n
Cloacal body temperature<\/td>\n32.2-35\u00b0C (90-95\u00b0F) 11<\/sup><\/a>,<\/sup> 31<\/sup><\/a><\/p>\n

Cloacal temperature is lower than true body temperature, therefore tympanic temperatures readings are more likely to accurately measure core body temperature.14<\/sup><\/a><\/td>\n<\/tr>\n

Heart rate<\/td>\nUsually between 180\u2013240 beats per minute (bpm) with a range of 70-300 bpm reported.\u00a08<\/sup><\/a>,<\/sup>11<\/sup><\/a><\/td>\n<\/tr>\n
Respiratory rate<\/td>\n25-40 breaths per minute 11<\/sup><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Anatomy\/physiology<\/h2>\n

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Dental eruption<\/strong><\/td>\nDeciduous teeth eruption is quite unique in the opossum. Incisors and canines as well as most cheek teeth begin to erupt and then are reabsorbed and replaced by adult teeth.\u00a01<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/p>\n

Permanent teeth<\/a> eruption occurs between 3-11 months.\u00a020<\/sup><\/a><\/p>\n

\"Virginia<\/a><\/td>\n<\/tr>\n

Dental formula, adult<\/strong><\/td>\nI 5\/4 C 1\/1 P 3\/3 M 4\/4 6<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>21<\/sup><\/a><\/td>\n<\/tr>\n
GI tract<\/strong><\/td>\nSimple stomach, non-fermenting gastrointestinal tract. 6<\/sup><\/a><\/td>\n<\/tr>\n
Integumentary<\/strong><\/td>\nOpossums possess a long, mostly hairless, prehensile tail and large, hairless ears. Male opossums also possess sternal scent glands (See Sexual dimorphism<\/a> below<\/em>). 10<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/td>\n<\/tr>\n
Musculoskeletal<\/strong><\/td>\nLike most marsupials, the opossum lacks an ossified patella. Opossums possess epipubic bones, which rest on and articulate with pelvic and pubic bones and serve as attachment surfaces for several abdominal muscles. 11<\/sup><\/a>,<\/sup>14<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/td>\n<\/tr>\n
<\/a>Reproduction<\/strong><\/td>\n<\/td>\n<\/tr>\n
Puberty<\/strong><\/td>\nFemales ~6 months
\nMales ~8 months
\nBreeding typically begins at ~10 months.\u00a011<\/sup><\/a>,<\/sup>13<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/td>\n<\/tr>\n
<\/a>Sexual dimorphism<\/strong><\/td>\nMales possess sternal scent glands. The secretions create a musky odor and stain the fur, particularly before the onset of the breeding season (see Reproduction<\/a> below<\/em>).\u00a029<\/sup><\/a><\/p>\n

Male opossums may also be slightly larger than females with larger canines.2<\/sup><\/a>,<\/sup>4<\/sup><\/a><\/p>\n

Males also possess a prominent scrotal sac on the mid-ventral abdomen. Females possess a pouch.<\/td>\n<\/tr>\n

Female reproductive tract<\/strong><\/td>\nOpossums are polyovular and polyestrous. Each lateral uterus opens into its own vaginal canal through its own cervix. The paired lateral vaginae open separately into the urogenital sinus at the level of the urethral opening and are separated along their length by a soft tissue median septum.\u00a011<\/sup><\/a>,<\/sup>13<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/td>\n<\/tr>\n
Estrous cycle <\/strong><\/td>\n29.5 days 29<\/sup><\/a><\/td>\n<\/tr>\n
Pouch<\/strong><\/td>\nLike many, but not all, marsupials the female opossum has a deep pouch or marsupium. The interior of the healthy pouch is sparsely haired and vascular and the surface is lightly to moderately coated with a yellow to black-brown, odorless, sebaceous secretion. The pouch contains a variable number (4-13) of teats.6<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>31<\/sup><\/a>\u00a0 Thirteen teats are most commonly observed (Johnson-Delaney, written communication to author, April 25, 2015).<\/td>\n<\/tr>\n
Males<\/strong><\/td>\nThe male opossum possesses a forked glans or bifid penis. The scrotum is prominent, pendulous, pedunculated, and pre-penile. Male opossums also possess sternal scent glands (see Sexual dimorphism<\/a> above<\/em>).\u00a013<\/sup><\/a>,<\/sup>29<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/p>\n

\"Bifid<\/a><\/p>\n

The urogenital tract of marsupials is significantly different from that of eutherian mammals. In all marsupials the urinary ducts pass mesially to the genital ducts, and in placental mammals they pass laterally. This results in male eutherians having the vas deferens loops around the inside of the ureter to reach the testes, and in male marsupials this loop is absent.\u00a013<\/sup><\/a>,<\/sup>14<\/sup><\/a><\/td>\n<\/tr>\n

Breeding season<\/strong><\/td>\nOpossums can breed year-round, but young typically emerge in the late spring.\u00a06<\/sup><\/a><\/td>\n<\/tr>\n
Internal gestation<\/strong><\/td>\n12-13 days 13<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/td>\n<\/tr>\n
Parturition<\/strong><\/td>\nDuring parturition, the fetus tunnels through the connective tissue between the median vagina and the urogenital sinus to form a central vaginal canal. Unlike most marsupials in which the birth canal is transient, in opossums this central vaginal canal becomes epithelialized and remains patent as a permanent median vagina.\u00a06<\/sup><\/a>,<\/sup>14<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/td>\n<\/tr>\n
Litter size<\/strong><\/td>\n4-25, with an average of 15, however litter survival is dependent on the number of teats. 29<\/sup><\/a><\/td>\n<\/tr>\n
Litters per year<\/strong><\/td>\nAverage one litter per year in northern regions, up to three annually in warmer climates.\u00a013<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/td>\n<\/tr>\n
Birth weight<\/strong><\/td>\n0.13-0.20 grams 29<\/sup><\/a><\/td>\n<\/tr>\n
External gestation<\/strong><\/td>\nJellybean-like embryos possess a well-developed pectoral girdle that allows the embryo to make the grueling trek from the birth canal to the pouch. Many joeys do not survive this trip. Once young reach the pouch, the ordeal may not be over. There are usually only 13 teats and some may not be functional. The nipple swells up in the neonate\u2019s mouth to secure attachment. The nipple also gradually elongates to provide increased security.<\/p>\n

Neonates possess a well-developed stomach and duodenum for digesting milk, however there are only rudimentary pelvic limbs and the kidneys are unable to concentrate urine. Young remain attached to nipples for approximately 50-70 days. Females average 8 pouch young per litter, although the number of teats determines the number that will survive. 6<\/sup><\/a>,<\/sup>14<\/sup><\/a>,<\/sup>29<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/td>\n<\/tr>\n

Lactation<\/strong><\/td>\nTo provide optimal growth, lactation varies widely throughout pouch life. Initially, marsupial milk is dilute, to support the joey\u2019s weak renal function, and protein and fat levels are low. Over pouch life, protein content doubles and fat levels quadruple. Mineral levels also vary in marsupial milk. High levels of copper and iron predominate early on, while calcium and phosphorus predominate at weaning. Marsupial milk contains only moderate levels of carbohydrates. The primary carbohydrate is not lactose, but an oligosaccharide. 6<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/p>\n

When handfeeding juvenile opossums, select a canine formula short-term\u00a022<\/sup><\/a>, then transition the joey to a commercial marsupial milk replacer (Wombaroo via Perfect Pets<\/a>) (Johnson-Delaney, written communication to author, April 25, 2015).<\/td>\n<\/tr>\n

Joey<\/strong><\/td>\n\n
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  • Eyes open at 56-64 days (~40 grams)<\/li>\n
  • Weaning begins at 70-84 days<\/li>\n
  • Fully weaned between 93-105 days<\/li>\n<\/ul>\n

    Young are usually independent after weaning, although some juveniles remain in the weaning den with their mother until they are ~120 days old. Approximately 60% of weaned free-ranging young do not survive once fully independent.\u00a029<\/sup><\/a><\/td>\n<\/tr>\n

Urinary system<\/strong><\/td>\nThe path of the ureters is unique in marsupials as they pass between the median and lateral vaginae on each side.\u00a031<\/sup><\/a><\/td>\n<\/tr>\n
Cloaca<\/strong><\/td>\nIn females, the urogenital sinus and rectum open into the common vestibule or cloaca.\u00a0The penis sits within the cloaca in males.<\/p>\n

Cloacal glands are present in both sexes and secrete a potent, viscous, green fluid.\u00a06<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/p>\n

\"Cloacal<\/a><\/p>\n

\"Expression<\/a><\/td>\n<\/tr>\n

Special senses<\/strong><\/td>\nThe retina is vascular with a tapetum lucidum. This nocturnal species has a rod to cone ratio of 50:1 (cats have 10:1). While Virginia opossums likely have keen eyesight, their ability to recognize color is limited. Opossums also possess sensitive vibrissae that assist their movement in the dark.\u00a06<\/sup><\/a>,<\/sup>29<\/sup><\/a><\/td>\n<\/tr>\n
Endocrinology<\/strong><\/td>\nThere is no thyroid function until about halfway through pouch life (see Thermoregulation<\/a> below<\/em>).\u00a06<\/sup><\/a>,<\/sup>14<\/sup><\/a><\/p>\n

The adrenal glands of normal females are twice the size of male glands. Cortisol is the most abundant corticosteroid. 14<\/sup><\/a><\/td>\n<\/tr>\n

Immunity<\/strong><\/td>\nOpossums lack true immune function until mid-pouch life, but fortunately immunoglobulin levels are concentrated in marsupial milk.\u00a06<\/sup><\/a><\/td>\n<\/tr>\n
<\/a> Thermoregulation<\/strong><\/td>\nIf the juvenile is removed from the pouch during the first half of pouch life, body temperature will closely reflect environmental temperature.<\/p>\n

The ability of young marsupials to regulate body temperature coincides with the start of thyroid function about halfway through pouch life. Thermoregulation occurs through evaporative mechanisms, such as panting, sweating, and licking.\u00a014<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/p>\n

Brown adipose tissue, which is used by eutherians to generate heat, is not found in marsupials.\u00a031<\/sup><\/a><\/td>\n<\/tr>\n

Metabolism <\/strong><\/td>\nThe metabolic rate of marsupials is lower than that of placental mammals. Opossums can enter a shallow torporous state for up to 11 hours in which body temperature drops between 11\u00b0C to 28\u00b0C.\u00a014<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/td>\n<\/tr>\n
Resistance to envenomation<\/strong><\/td>\nA remarkable resistance to envenomation by venomous snakes has been reported in the Virginia opossum.\u00a04<\/sup><\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Restraint<\/h2>\n

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The 50 teeth of the Virginia opossum can be intimidating, however opossums lunge and bite only on rare occasions (see defensive behavior above<\/em>). Instead most individuals will hiss and sit still during transfer or sedation.<\/p>\n

Most opossums can be restrained by wrapping a towel around the body or placing the animal on a flat surface with the towel draped over the head while grasping the tail base. Keep in mind that females can eject pouch young during capture and restraint.<\/p>\n

If the opossum is aggressive, wear leather gloves. Sedation or inhalant anesthesia like isoflurane or sevoflurane, is particularly useful for fractious animals or more invasive procedures.\u00a06<\/sup><\/a>,<\/sup>11<\/sup><\/a>,<\/sup>17<\/sup><\/a>,<\/sup>21<\/sup><\/a>,<\/sup>31<\/sup><\/a><\/p>\n

Juvenile opossums can be kept in a cloth pouch or pocket. 11<\/sup><\/a>
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Preventive medicine<\/h2>\n

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\nVeterinarians are permitted to provide humane veterinary care to any injured or orphaned wild animal. Further rehabilitation and eventual release of wild animals must be performed by licensed individuals.\u00a017<\/sup><\/a> Opossums that have been hand-reared, are too habituated to humans, or have permanent disabilities can be kept as pets in some cases. In many jurisdictions, this requires a permit and veterinarians should be aware of the wildlife regulations concerning the opossum in their area.<\/p>\n