Thyme oil may have a strong effect on your dog, however, thyme plant itself is pretty safe for dogs. Unlike thyme oil, it does not have a high concentration of thyme substances and can be safely consumed by dogs. Though, thyme is not one of the dogs’ favorite plants. They leave them pretty indifferent. However, in some cases, when this plant is consumed in large quantities, it can evoke such symptoms as vomiting or diarrhea.