Care of the Virginia Opossum

Abstract:

The Virginia opossum (Didelphis virginiana) and the striped skunk (Mephitis mephitis) are often kept as pets, although they are both wild animals. The opossum  and striped skunk are usually docile  and sociable when raised from infancy. Many states and municipalities restrict ownership, and veterinarians should familiarize themselves with local laws and regulations pertaining to these animals. The biology, husbandry, diet, and general disease information is available for both species. Vaccination recommen- dations are included for skunks. Copyright 2014 Elsevier Inc. All rights reserved.

The Virginia opossum (Didelphis virginiana) and the striped skunk (Mephitis mephitis) are often kept as pets. Both are nondomesticated animals and considered wildlife. Many states and municipalities prohibit their ownership, so veterinarians should be aware of local laws and regulations governing ownership. Although most skunks in the pet trade come from vendors that breed the animals and are sold preneutered and having had their anal scent glands

removed, most opossums are raised from infancy as orphaned wildlife. Both species, when raised from infancy, can be quite docile. Both are latrine animals and take readily to the household environment.

The Virginia opossum is the only marsupial native to North America. It is often called a “possum,” although Old World “possums” are “possums” and New World “possums” are correctly named “opossums.”1 In many areas, Virginia opossums are considered vermin or pests. Most opossums become pets when rescued as pouch babies or newly outside of the pouch owing to the dam having been killed, usually on the road. Owing to the high incidence of opossums being roadkill, they are usually thought of as unintelligent and slow. In reality, the opossum is a successful

marsupial and has increased its habitat. It was introduced into California and has since increased its range northward into British Columbia. Pet opossums respond to their names and seem to respond to basic commands such as “no.” They are fastidious in their grooming and are latrine animals, taking to newspapers or even litter boxes.

Opossums appear to enjoy being held and may curl up in their owner’s lap and enjoy riding around on their owner’s shoulders.

Opossums found as furred infants and beginning to spend time out of the pouch can be successfully hand-reared and readily bond with their human caregivers. Joeys that are unfurred in the pouch are rarely raised to full size. The National Opossum Society has published detailed

infant diets and feeding instructions and growth information for the Virginia opossum.2 The basic formula can be made using either Esbilac or Multi- Milk (PetAg, Inc., Hampshire, IL USA) at either a

1:3 or 1:5 dilution with distilled water. Added to the primary opossum infant diet are egg yolk, brewer’s yeast, apple juice, or boysenberry low-fat yogurt.3,4

House opossums should be spayed or neutered. For female animals, removal of the ovaries and reproductive tract decreases the likelihood of chronic urogenital tract infections. In males, neutering decreases scent marking and odor. As pets, the biggest challenge may be to prevent obesity by providing sufficient exercise, as opossums have a tendency to be sedentary. They startle easily and do not usually interact or play with other pets, so human supervision, when the opossum is free within the house, is recommended. A frightened pet opossum often runs back to its cage/bed or to a place of safety.

One deterrent to having opossums as pets in the eastern United States and California is the zoonotic potential of Sarcocystis spp., which opossums may carry and can cause major problems for horses, sea otters, and Old World psittacines; therefore, one needs to exercise caution when handling feces from these animals. Stools should be examined frequently for protozoa. Fecal flotation for evaluation of gastrointestinal parasites is required for newly acquired joeys as many are parasitized by nematodes.

Anatomic Variations

Virginia opossums have 5 toes, including an opposable thumb on both the front and hind feet. The brain size is one-fourth that of a cat of comparable weight and their dental formula is 5/4, 1/1, 3/3, 4/4. The female’s pouch has a variable number of nipples (Fig. 1), while the vagina has a central and 2 lateral canals with 2 separate uterine horns. Ovariohysterectomy may incorporate the lateral vaginas, but care must be taken to separate the ureters from the loop between the central and

lateral vaginas.5  Both sexes have marsupial bones,

which appear as “ribs” extending proximally from the pelvis (Fig. 2). Males have a forked glans penis (Fig. 3), with the scrotal sac having a midventral position. Castration is performed as in other marsupials by ligating the single stalk, with ablation of the excess scrotal tissue. Cloacal glands are present in both sexes and secrete a strong- smelling, thick greenish-colored fluid.

Opossum fur is wooly instead of smooth and can be found in nearly any color from black to white and, in some regions, nearly a cinnamon color. Cinnamon opossums have shorter fur than normal-colored opossums. True albinos with pink eyes, ears, feet, and tail have been identified. Another mutation has white fur but normally pigmented skin.1