ABSTRACT
There are over 100,000 species of spiders. Spiders are beneficial to humankind, yet many people believe that every spider is waiting to envenomate and kill any unsuspecting person happening by. Venomous spiders may be small or large. Large, hairy spiders are universally feared as being highly venomous, but not all are so. Spiders are generally shy and will withdraw if possible. Animal spider encounters are bound to occur if an animal accidently blunders into a web or harasses a spider. Young animals are more likely to be attracted to diurnal spiders moving about an area, and may even attempt to play with them. Spider venom is complex and varies from species to species. In addition to numerous enzymes, other nonprotein substances (y-aminobutyric acid, polypeptides) may contribute to the toxic effects. The pharmacologic response of an anesthetized dog and cat to intravenous funnel-web spider venom is that of transient hypertension, tachycardia, body temperature decrease, and increased cerebrospinal fluid pressure.
