Safety is also a consideration. In September 2018 the US Food and Drug Administration (FDA) released a statement warning about the risk of tremors and seizures in animals treated with products containing drugs in the isoxazoline class, which are used to combat fleas and ticks. However, the FDA said it still considers the products "safe and effective".
Puppy Roundworms can infect humans. To prevent this infection, puppies should be wormed regularly throughout their first year of life, and owners should be thorough with their own personal hygiene after having interacted with the dog. Tapeworms, Hookworms, and Whipworms can also infect dogs, and your veterinary surgeon can advise when to worm the dog.