The North American opossum (Didelphis virginiana) is a solitary, nocturnal scavenger often encountered in suburban and rural areas. As the only marsupial found north of Mexico, this creature is frequently misunderstood, leading to exaggerated fears about the danger it poses to people and pets. Opossums are non-aggressive opportunists that prefer to avoid conflict, relying on specialized defense mechanisms. Understanding their behavior and the actual risks clarifies that the threat they pose is minimal compared to other common wildlife. This article explores the specific risks associated with opossums, focusing on physical confrontation, disease potential, and interactions with domestic animals.
Physical Threat and Aggression
Opossums are inherently non-aggressive creatures that will rarely initiate a confrontation with humans or pets. Their primary response to danger is a passive defense mechanism known as “playing possum,” or tonic immobility. This involuntary, comatose-like state is triggered by extreme fear, causing the animal to collapse, drool, and emit a foul-smelling fluid from its anal glands. This deters predators that prefer live prey or are repelled by the smell of decay.
If unable to flee, a cornered opossum may engage in a defensive display. It will hiss loudly, screech, and bare its fifty sharp teeth, the most of any North American mammal. While this display looks intimidating, it is a bluff intended to frighten away the threat, not an offensive attack. Bites to humans or pets are extremely rare and virtually always occur only when the opossum is severely provoked, handled, or attacked.
Disease Transmission Risks
A common misconception is that opossums frequently carry the rabies virus, but their unique physiology makes this highly unlikely. The opossum’s average body temperature, which is approximately 94–97 degrees Fahrenheit, is generally too low for the rabies virus to thrive and replicate effectively. While any mammal can technically contract the virus, the rate of rabies infection in wild opossums is exceptionally low, making them a minimal vector for transmission.
Opossums can carry other pathogens and external parasites that pose a risk to humans and pets. They can transmit bacteria like Leptospira, which causes Leptospirosis, a disease spread through contact with infected urine or contaminated water sources. Opossums are also carriers of the parasitic protozoan Sarcocystis neurona, shed in their feces, which can cause Equine Protozoal Myeloencephalitis (EPM) in horses if they ingest contaminated feed or water. Furthermore, their presence introduces external parasites like fleas and ticks, which can transmit diseases such as Lyme disease to pets and people.
Impact on Household Pets
Opossums do not prey on domestic animals and will almost always prioritize escape or playing dead over fighting a dog or cat. When an interaction occurs, it is usually initiated by a curious or protective pet, most often a dog. If an opossum is cornered by a dog, it may bite defensively, and its sharp teeth can inflict puncture wounds, though serious injury to the pet is uncommon.
The greater risk to pets is indirect, stemming from secondary exposure to pathogens. Opossums can contaminate outdoor pet food and water bowls with feces or urine while scavenging, which can transmit diseases like Leptospirosis, Coccidiosis, and Salmonella. To reduce this risk, pet food should be stored indoors and bowls should be cleaned and brought inside overnight. Dogs are more likely to engage than cats, making it necessary to monitor pets during nocturnal hours.
Safe Coexistence Guidelines
The most effective way to minimize encounters is to eliminate the food and shelter sources that attract opossums to a property. All outdoor pet food and water should be removed before dusk. Garbage cans must be secured with tight-fitting, clamped lids, and attractive food sources like fallen fruit or spilled birdseed should be cleared from the ground regularly.
To prevent opossums from denning on your property, seal off all potential entry points to crawl spaces, sheds, and under porches or decks. If you encounter an opossum, the best practice is to leave it alone, as it is a transient animal that will typically move on within a few days. Never attempt to handle a wild opossum, and if one appears sick, injured, or trapped, contact local animal control or a wildlife rehabilitator for professional assistance.