Can Fleas Cause Your Dog To Get Sick?

Can Fleas Cause Your Dog To Get Sick? Within just three short weeks, a single flea can infest your dog with more than 1,000 blood-sucking descendants. While uncomfortable for your dog (and your unprotected ankles), fleas can also cause anemia, allergic reactions and infections. Fleas can also transmit tapeworms. What kills fleas on dogs instantly?