Fleas are the most common external parasite of dogs and cats.  The cat flea, Ctenocephalides felis, affects both cats and dogs and in North America most dogs infested with fleas...

Heartworm disease is an increasingly prevalent condition in dogs throughout North America. Heartworm disease also affects cats, ferrets, and even humans. Transmitted by mosquitoes,...

Giardia is a protozoal parasite found worldwide. It infects many mammals, including dogs, cats, and even humans. In dogs, it commonly causes diarrhea, although many infected dogs...