Last night I saw my cat play with something. It turned out to be a spider—a black widow! I got it away from her, and she’s showing no problems, but how dangerous could this have been?
A: More than 20,000 species of spiders are found in North America, and all but two are venomous. Thankfully, only about 50 have fangs that can puncture mammalian skin. In general, hunting spiders (like the brown recluse) have more potent venoms than web spinners—with the notable exception of black widows. This spider is found in every state but Alaska and prefers dark, dry, draftless areas like woodpiles, garages, basements, attics, closets, cupboards, and sheds. Males are venomous but cannot deliver a toxic bite; females can be 20 times the size of males. Most bites on pets and people occur in the winter when spiders come inside houses. Clinical signs of black widow bites develop 30 to 60 minutes after a bite. Dogs and cats show severe pain, muscle cramping, tremors, vomiting, diarrhea, and abdominal tenderness. Cats are more susceptible and may howl in pain. Rarely will you see the bite punctures—or the spider. Treatments include pain management, muscle relaxants, and an antivenin. Prevent spider bites by keeping a hygienic environment clear of debris and not allowing pets to have unsupervised access to attics, garages, sheds, and basements. If you suspect your pet has been bitten by a black widow, contact your veterinarian immediately.
I live in Denver and let my dog and cat go out in my yard. I’ve seen coyotes, foxes, raccoons, skunks, bats, hawks, and owls in our neighborhood—how much danger do they pose to my pets?
A: In 1990, about 40 percent of Americans lived in urban centers; by 2030 it is expected to be up to 60 percent. This steady urban growth has had a powerful effect on animals, with some species learning to exist in cities. In Denver, we routinely find bats, squirrels, raccoons, skunks, rabbits, foxes, coyotes, deer, pigeons, hawks, owls, and occasional bears and rattlesnakes. Wild animals can transmit contagious diseases to us and our pets. In Colorado, skunks, bats, raccoons, and foxes are the major vector of rabies. Wildlife can infect streams, creeks, lakes, and ponds with the agents responsible for Leptospirosis and Giardia. Raccoons also carry distemper and a nasty parasitic worm. What can you do? Avoid any contact with wild or stray animals, and do not handle even carcasses bare-handed. Make sure your yard is secure and your animals do not wander outside of it. Secure all garbage cans with latch-able lids that do not attract scavenger wildlife. Keep pet food and water dishes inside, not on porches, where animals can find them. Finally, keep your pets’ vaccines up to date.
Kevin T. Fitzgerald, PhD, DVM, is staff veterinarian at the VCA Alameda East Veterinary Hospital.
