Warm summer months are the prime time for mosquito populations to thrive. With that comes the threat of mosquito-borne diseases for people and pets. It typically takes six months for the symptoms of an infected dog or cat to be noticeable. The earlier the heartworms can be detected and treated, the higher the likelihood for the animal to be healthy again. NBC's Britney Glaser finds out what's behind the summer spike in dangerous heartworm infections.