The most common external parasite found on pets is the flea. Fleas are tiny, wingless insects that feed on the blood of mammals, including dogs and cats. They can cause significant discomfort through itching and scratching, leading to skin irritations and potential infections. Fleas also serve as a vector for other parasites, such as tapeworms, and can transmit diseases. Prevention and management often involve regular grooming, topical treatments, and maintaining a clean living environment. Pet owners should be vigilant in addressing flea infestations, as they can spread quickly and become a household issue.