Friday Parasite: Dog Lovers Beware

The blue-stained roundworm on the right is the reason the veterinarian wants you to give your dog a heartworm pill each and every month. It's Dirofilaria immitis, a filarial worm that likes to take up residence in the heart and pulmonary arteries of canids. At least, adults like to live in the heart. Their babies prefer to ride the bloodstream, moving to the tiny vessels under the skin each night in the hopes of getting a ride from a hungry mosquito. After a couple of molts in the mosquito's body, they migrate to its salivary glands and wait for the insect to find them a new host.


Image: Cornell Veterinary College