When Elizabeth Estes's dog, Ollie, started coughing last year, she didn't think he was seriously ill at first. But then the 3-year-old Jack Russell-chihuahua mix got much worse.
"All of a sudden, he couldn't breathe and he was coughing. It was so brutal," says Estes, who lives in Chicago. "The dog couldn't breathe. I mean, could not breathe — just kept coughing and coughing and coughing and gasping for air."