If your dog eats an ant trap, it is generally not cause for concern. The Pet Poison Helpline lists ant baits as minimally toxic. The Pet Poison Helpline does, however, recommend calling your veterinarian any time your dog eats a toxin.
About Ant Bait
Ant bait traps contain an insecticide and a substance, such as peanut butter or bread crumbs, to attract the ants. Unfortunately, dogs are drawn to the attractants too, so always place traps in locations dogs can't access. Commonly used trap insecticides include boric acid, avermectin and sulfluramid. Exposure to trap insecticides does not require treatment or decontamination according to veterinarian Sharon Gwaltney-Brant of the Veterinary Support Personnel Network. She also notes that if there are reactions, they are usually mild.
About Trap Housing
A larger concern when a dog eats an ant trap is the trap's plastic housing. There is a possibility that the plastic fragments could cause intestinal obstruction and alimentary tract damage. Freelance veterinarian Scott Nimmo of Essex, UK recommends feeding your dog a few slices of bread or some mashed potatoes to cushion sharp edges of plastic fragments as they pass through your dog's system.
What to Watch For
If your dog has eaten an ant bait trap, and you notice vomiting, diarrhea, straining, lethargy and decreased appetite, call your veterinarian immediately.