Heterobilharzia americana infection in dogs | VETgirl Veterinary Continuing Education Podcasts

In this VETgirl online veterinary continuing education podcast, we review Heterobilharzia americana (HA) infections in dogs. HA is a trematode parasite that can infect our canine patients, causing a condition known as schistosomiasis and potentially severe granulomatous disease. We know that specific snails are the intermediate host, and that dogs swimming in freshwater lakes or streams are often exposed to the free cercariae that have been released by an infected snail. The organisms infect the dog by dermal penetration, and can then migrate via the bloodstream to cause damage elsewhere and eventually to mate. Specifically, the organisms move to the liver and to the lungs, where they sexually mature into adult parasites. These adults can move via the portal system, and they mate and release fertilized eggs in the mesenteric veins. Enzymes facilitate transport of the eggs into the intestines, and they are ultimately excreted in the feces. To round out this process, a new stage of the organism, the flagellated miracidia, is released from the eggs to infect snails if the feces comes in contact with fresh water. And so the cycle continues!