Are garden snails poisonous for humans to eat?

Yes, snails may be toxic to a dog. Fresh water snails can carry rickettsial organism. The symptoms last around 5-7 days. They include fever, vomiting, diarrhea (usually bloody or bright yellow in color), and some other not so pleasant symptoms. If left untreated it has up to a 90% mortality rate. This same condition can be picked up from eating raw fish, especially salmon.