For the most part, these preventives are very well tolerated. Sometimes you’ll see local site reactions where you apply the topical; they'll lose hair and get itchy. On occasion, I've had owners report cats that just don't feel well after the topical is applied. If we suspect that the heartworm preventative is causing some lethargy or depression, we'll switch products.

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.

X-rays, monitoring, and bracing owners that this cat may go into a fatal crisis when this heartworm dies (they live about two years). There's not a whole lot you can do to prevent that. Despite the best of efforts, those cats die. Sometimes specialists can surgically/manually remove heartworm, but it’s costly. How often it's done, I'm not sure. It's probably a pretty risky procedure, too, I would think.

It can prevent it. I don't think the research has been done out there yet to see if chronic prevention eventually treats or kills the heartworm. Having an adult heartworm die is often fatal to the cat, so we can’t let anything reach adulthood by prevention.

If you miss a dose, keep going. As soon as you realize you've missed it, go ahead and give the cat another one and just go on their regular monthly routine. If they are not showing any symptoms, great, we don't go any further with that.

If a cat does get an adult heartworm or two, there is no treatment available. They can't get the conventional treatment that dogs do. The medication is somewhat toxic in a cat. Then as the worm dies, the cat often dies as well, which is why prevention is so vital. If infected, the cat develops chronic asthma-like symptoms once infected with heartworm, and that lasts for life. That's treated with things like corticosteroids and bronchodilators as needed, but there's permanent damage done to the lungs.