If it's small and moves, cats will probably try to eat it or play with it. So spiders are prime targets. Most species are harmless to cats, but not all of them. Three species in particular can be highly toxic to cats. If you suspect spider poisoning, call your vet at once.
For the most part, spiders will not hurt your cat, whether she tries to eat or ambush them. A cat's skin and fur is too thick for most spider species' fangs to penetrate. If a spider does manage to land a bite, symptoms will generally be topical -- itchy bumps or welts, similar to those ofmany other kinds of insect bites. Typically and discomfort will wane in a few hours or days, or your vet may prescribe medication.
The black widow spider is highly toxic to cats, dogs and people. Different varieties of black widow exist all over the United States. The female in particular is recognizable by her shiny black body and the red hourglass-shaped marking on her abdomen. Symptoms of a widow bite include paralysis or rigidity, severe upper body pain that causes yowling, tremors, difficulty breathing, loss of coordination, vomiting, diarrhea and heavy salivation. Antivenin treatment is needed quickly to stave off death.
The brown recluse, aka the fiddleback, is especially common in the Midwest. The recluse prefers to hide in woody areas where damp logs abound, making run-ins with cats relatively rare. But a confrontation can be painful for a cat. A bite site may sting for up to eight hours. White lesions with dark scabs may develop over several weeks. Less commonly, cats may develop fever, rash or nausea. If left untreated, a brown recluse bite can cause severe tissue damage in a cat.
Bites from the brown and shaggy hobo spider typically mimic those of the brown recluse but can have more severe results. Tissue damage begins at the bite site as an itchy red-and-white lesion. If left untreated, skin and tissue likely will die as the deterioration spreads. Though more common in Europe, American hobo spiders mostly live in the Pacific Northwest. They are most recognizable by the funnel-shaped webs they spin to catch their prey.