Worms can be a silent enemy to your furry friend. Common types of intestinal parasites include roundworms, tapeworms, hookworms, and whipworms. These parasites can affect dogs of any age but are particularly dangerous for puppies and elderly dogs, who may not have fully developed or robust immune systems. The symptoms of worm infestations can range from mild to severe, including vomiting, diarrhea, weight loss, lethargy, and even abdominal pain.