Heartworms (Dirofilaria immitis) are a species of parasitic roundworms that primarily infect dogs, but can also infect cats, wild canids, and, in rare cases, even humans. They are found in every state in the country and spread from one host to the next through mosquito bites, which deposit larval heartworms into the new host when they feed. Since their lifecycle depends on mosquitos, infection rates are on the rise as human activities, such as irrigation and urban development, create new habitats suitable for mosquitos. Heartworm infections develop slowly, with symptoms often presenting themselves only months past since the initial transmission.
The first symptoms are innocuous enough, just a slight cough. As the worms grow and lodge themselves in the arteries leading into the heart and lungs, the coughing becomes worse and persistent. The dog will exhibit difficulty breathing and a reluctance to exercise, which gets worse as time goes on. Eventually, a severe infection