Is early detection and diagnosis of heartworm more difficult in cats?

Yeah, it’s challenging in cats. Cats often test negative for everything, but they're infected with heartworm because it does different things in a cat. If a cat has asthma-like symptoms, and cats get asthma anyway, it's an allergic lung disease, but it can also be triggered by heartworm. It's often an educated guess. The treatment is the same as treating asthma, with steroids, bronchodilators, things like that, but we’re still going to have to figure out if heartworm is the underlying cause. If we suspect heartworm, we may do antigen testing later to see if it was heartworm that caused the asthma attack, and we may never know.

The incidence in cats is much lower than a dogs because it is a dog parasite for the most part. Cats’ lifestyles and things like that make them a little less susceptible as well. But it's the cat's immune system reaction to the parasite when they get infected that causes all the cat symptoms more than anything.