My thoughts as well.
Dogs possess a sense of smell many times more sensitive than even the most advanced man-made instrument. Just how powerful is a pupper schnoz? Powerful enough to detect substances at concentrations of one part per trillion—a single drop of liquid in 20 Olympic-size swimming pools. With training, dogs can sniff out bombs and drugs, pursue suspects, and find dead bodies. And more and more, they’re being used experimentally to detect human disease—cancer, diabetes, tuberculosis, and now, malaria—from smell alone. - https://www.wired.com/story/the-science-of-the-sniff-why-dogs-are-great-disease-detectors/
Dogs can detect dead bodies under water! (The bodies).