Heterobilharzia americana is a parasite that infects dogs causing a disease known as canine schistosomiasis. The parasite infects dogs as they spend time in freshwater such as rivers, lakes, streams, and ponds. Until recently, this parasite was thought to be limited to the Gulf and Southern Atlantic states with isolated reports of dogs being infected without traveling to regions where the parasite was known to reside. Recent outbreaks of infected dogs in California and Utah have caused significant concern among dog owners and veterinarians. In Western States, such as California and Utah, most veterinarians are not expecting to see this particular parasite and it often goes undiagnosed. The investigation into each of these two outbreaks led to the first ever documentation of the specific water source of infection. In this study, we will determine the prevalence of canine schistosomiasis in 600 dogs in the Southwestern US, a suspected new and rapidly emerging endemic region. Simultaneously, we will perform a survey of freshwater bodies along the Colorado River across California, Arizona, Utah, and Nevada. The research team’s hypothesis is that canine schistosomiasis has significant prevalence in dogs in this region and that a wide range of freshwater bodies along the Colorado River pose significant risk to dogs who reside or travel to these regions. The results of this work will inform the development of effective prevention strategies and actions to protect the health of dogs in this region.