The opossum is an interesting creature indeed. Whether they are heroes or villains depends on what animals you share your home with.
Commonly called "possums", they are one of the very few marsupials in North America. Marsupials bear live young but in a very immature stage. The tiny offspring then migrate their way into the pouch of the female where they attach to nurse and develop.
Opossums serve an important function in an ecosystem. Despite the impressive collection of teeth, opossums are not hunters and are not aggressive. They are true scavengers, eating carrion, berries, human trash and cat or dog food left outside.
An opossum who is attacked will almost always go into the famous "playing dead" act. They collapse, roll over and literally appear dead. They can even be picked up and carried in this state and won't react. When all is safe, they revive and run.
The hero part of the opossum story comes in the guise of tick killing. Like so many small mammals, opossums become tick hosts. The hero part is that opossums are incredibly good at grooming. They remove and eat over 90 per cent of the ticks that attach to them. That means all those ticks are removed from the Lyme Disease causing population of ticks!A healthy local opossum population means less ticks in the neighborhood.
The villain status of opossums comes from being the definitive host of an intestinal parasite called Sarcocystis neurona. This protozoa is the cause of EPM or Equine Protozoal Myelitis in horses - a very serious, often fatal disease of the equine neurologic system. The opossum becomes infected by eating an infected carcass of a raccoon, skunk, armadillo or cat. The immature protozoa are passed in opossum feces.
A horse may eat infected feces in grass, caught up during haying in a bale or in water where fecal material has collected. The goal is to discourage opossums near your barn or in your fields. Don't leave food out for barn cats where it might attract an opossum. Close up barns at night during bad weather so an opossum doesn't seek shelter there. Make sure your horses have plenty of grass to graze out in your pastures. Horses will avoid fecal contaminated grass and hay if at all possible. Encourage your horses to drink from water tubs and fence off creeks and ponds if need be.