This article from eHow, "What to Do If a Dog Eats Ant Killer" allayed my fears.
"A quick response may save your pet's life, but depending on the chemical involved, home remedies may be all you need," explains writer Mary Earhart.
Her advice? Read the label. Avermectin is one of the more common and least threatening to your dog's health when ingested in small amounts. Avermectin accounts for just 0.01% of the contents of the sugar-laden bait Sadie had in her mouth. And avermectin is not all bad: It is an active ingredient in Heartgard to treat heartworms in dogs. So, it seems the situation is not critical.
Just to be sure, I phoned Sadie's vet. Sadie weighs 60 pounds and had not actually eaten the trap. She chewed it like a toy. The fact she had not swallowed the trap whole is yet another reason not to worry too much, he explained. His advice? Keep an eye on her and watch for lethargy and any foaming at the mouth. If that happens, call the ASPCA Animal Poison Control Center, which is best suited for walking pet owners through necessary steps to diagnosing and troubleshooting poisoning. Here is the number (note: there is a $65 fee, but it's cheaper than an ER visit): 888-426-4425
We'll have to do a better job of hiding these traps. Or find a dog-friendlier alternative.