i work in a vet clinic, so I can accurately say, yes they can. It depends on the age of the puppy, breed and size. It should ONLY be applied by someone who knows what they're doing. Mitaban has very serious side effects in dogs AND people. It affects the nervous system. It is dangerous to breathe as well. It is easily absorbed through the skin in humans, and can cause liver damage with long term use. In dogs and cats, it is known to cause vomiting, diarrhea, vomiting, excessive urination, and neurological symptoms. A few owners reported their dogs become aggressive after using Mitaban. The chemical in Mitaban is also used in preventic tick collars and promeris for cats. Definately speak with a vet before using!!!!