Worms have been with dogs before humans actually started petting them. But due to controlled feeding, weather, mental state, etc. the devil of worms increased a lot. Worms not only hinder the growth of your dog or cat, but they can also make them sick, very sick. And if left untreated it can lead to death too. Parasites like worm thrive on dog's nutrition. Which leads to mentally irritated, weak dogs. And these worms have tendency to spread to various organs of dog's body. And once they reach target organ; they can be fatal and dangerous. For example heartworm in dogs can cause issues to heart and lungs of your dog. Worms are not beneficial to dogs (I wish dogs adapt cidal effects naturally). They grow and multiply on host bodies. So why worms are bad for my dog? Well, as we said earlier; worms stay and multiply in various organs of the host (read dog here). While doing so they do some reversible (when treated earlier) and irreversible (delayed or no treatment) to ph