Why can so many things here kill you?

Now that Drew and I are living outside of central Tucson we are running into a lot of poisonous creatures. Already Drew saw a black widow in the garage last night. A few hours later, I walked out front and saw this guy:

It's a Colorado river toad. Their venom contains a hallucigenic tryptamine compounds that, if ingested, are poinsonous enough to kill a large dog. At our old house Scout had a tendency to chase down and then eat lizards and birds, therefore, I am a little worried about these guys. Luckily this one was in front and our dogs are never out there alone. I am hoping that a combination of the noise we make in the back and the smell of dog urine will keep most toads and snakes away. But to be on the safe side our dogs are being escorted every time they go out.