Hey Einstein,

We’ve had so much rain lately, I’m afraid I’m going to start growing webs between my toes. My humans are even building an Ark in the backyard. I heard them say something about getting two of each kind of animal so they can repopulate the Earth. I don’t know how much repopulating I’m going to do since they neutered me. They said, “All the animals.” I hope they leave the bugs behind. There are mosquitoes buzzing all over the house. Even though I’m an inside cat and my humans keep flea stuff on me, I still get strafed. If they bring those pests along, I hope they also bring a mosquito net. What can I do to get them to stop from bugging me?

Noah from Mesquite

Ahoy there, Noah,

Tell your people, if the insects come with you, they need to double up on mosquito-eating frogs. And it couldn’t hurt to bring along a couple of cases of Raid, too. Mosquitoes are more than just annoying bugs. Those smart guys at the Central Massachusetts Mosquito Control Project told me that throughout history mosquitoes have killed more humans than all the wars, famines and natural disasters combined—that’s more people than are alive in the whole world today. Heck, you don’t have to read ancient history to know that those little suckers are bad news. This year alone, between three and six million people will die from mosquito-borne malaria. And 100 million get sick from it every year. But people aren’t the only animals who have an invisible target on them. For years vets have known that mosquitoes could give dogs heartworms, but they believed we kitties were safe. Now, they know that cats are on the menu, too. Bummer. This one vet from Beaumont, Texas did necropsies on cats put to sleep by the city shelter and learned that twenty-six percent of all the healthy cats in his area had heartworms.

You may think that doesn’t matter to you, cuz you live where it’s usually hot and dry. But with the recent monsoon, the mosquitoes have been fruitful and multiplied. I guarantee you, even if you’re folks don’t invite them on the boat, they’ll stowaway.

Kitties get heartworms the same way dogs do, by mosquito bites. They affect us differently than dogs, but they’re just as serious. And just because you’re a strictly indoor cat doesn’t mean you’re exempt from heartworm worry. The little buggers can sneak inside through a hole in the screen or when the kids run in and out. In one North Carolina study, 28 percent of the cats diagnosed with heartworms were inside-only.

Last year, this feline reporter interviewed Dr. James R. Richards, the late Director of the Cornell Feline Health Center.

“It is a very serious disease, but also, very preventable," Dr. Richards told me. He added that heartworms are a misnomer from the feline perspective; they actually cause lung disease in cats. It’s called Heartworm Associated Respiratory Disease (HARD.) And it’s a HARD row to hoe for any kitty unfortunate enough to be bit by the wrong mosquito.

New research shows that it’s not just the adult heartworms that can kill us kitties. The larvae can do us in, too.

Mosquitoes pick up heartworm larvae when they drink the blood of an infected animal like a dog, coyote, wolf, fox or kitty. Vets call that poor pooch or puss a “reservoir.” Later, while the mosquito enjoys another feast of cabernet catus, it injects the heartworm larvae into the new cat. Over the next 90 days, the nasty little larvae travel from the skin to the veins. Once they hit the circulatory superhighway the larvae get a passport stamp through the heart and into the cat’s lungs and the nearby arteries. (Not to gross you out, but they can also migrate to the brain and the eyes.) By now these larvae are a whopping two-inches long. Most of those immature heartworms meet their maker at this stage in the arteries around the lungs. Dead heartworms aren’t necessarily something to celebrate cuz the damage is already done. Dead, they still cause even more swelling of the blood vessels. Here’s the tricky part: in kitties symptoms can start showing up with only one heartworm larva. But, some heartworm cats never show any symptoms at all. Often, the first sign of HARD is when the cat dies suddenly. Numbers vary, but somewhere between ten and seventeen percent of heartworm kitties wake up dead with no symptoms at all.

When symptoms do raise their ugly head, vets often mistake them (coughing, wheezing, difficulty breathing, exhaustion, puking and loss of appetite) for asthma or another respiratory ailments. Heartworm kitties can also die from blood clots in the lungs. When the worms invade the eyes and brain, the poor cat suffers those types of symptoms.

They’re almost impossible to diagnose. Those in-office heartworm tests vets use for pooches, won’t work on cats. Vets can run the Feline Heartworm Antigen Test in just a few minutes. That test isn’t foolproof cuz it’s sexist. The antigen has to come from a mature female heartworm. Guy heartworms don’t count even if they can kill you just as dead. Immature females or male-only worm infections usually test negative. And it often takes at least four mature girls to show up in the test. Vets have to look at the big picture, (test results, X-rays, ultrasound scans, and symptoms) to diagnose heartworms in us.

Adding insult to illness, heartworm dogs can be given medicine to kill the parasites. They tried that on a few heartworm kitties, but it wasn’t a happy ending. When the dead mature heartworm lets loose and started circulating, they caused fatal clots. In killing heartworms, size matters. Since most dogs are larger than kitties (with bigger blood vessels) they can usually tolerate little chunks of dead worms circulating around their bodies. But we kitties are more delicate than our canine counterparts. If the medicine doesn’t kill us, the stroke or blood clot caused by dead worms will. The sad truth is, a dead heartworm circulating in the blood is more deadly than the live one lodged in our lungs.

Vets use steroids like prednisone to reduce inflammation and asthma inhalers to make breathing easier. The steroids help control symptoms but it’s not a “cure” for heartworms. So if you had heartworms, they’d put you on a preventative like Revolution or Advantage Multi (so you don’t get infected with more of them) and allow the heartworms to die naturally. Sometimes vets will go in and remove them surgically.

Back to statistics: Heska, a company that makes one of the heartworm tests, says that 15.9% of kitties with symptoms nationwide are actually positive. This isn’t counting cats who haven’t started showing symptoms. But that Beaumont, TX vet found 26% of healthy kitties were suffering from HARD.

According to a survey released by the American Heartworm Society, in 2004 over 250,000 dogs and cats tested positive for heartworm infection in the U.S. Some of these infected pets will move into areas that don’t have heartworm problems. Remember those “reservoir” dogs and cats? When heartworm pets move, they give those hungry mosquitoes in unaffected climates a way to spread the misery. But wait, there’s more bad news. Vets believe that 60 percent of the dogs evacuated after Hurricane Katrina were heartworm positive. Now, heartworm reservoirs have conveniently been spread all over the country. So, Noah, even if heartworms haven’t been a problem in your area, they will be.

As with most kitty illnesses, prevention is the best treatment. It’s really the ONLY treatment. Revolution, Advantage Multi™ and Heartguard for Cats all contain heartworm preventative. Revolution and Advantage Multi™ have the added advantage of being one-stop bug-icides that only have to be applied to the back of the neck once a month. These topicals get rid of most intestinal worms (except for tapeworms), ear mites and fleas. They won’t kill adult heartworms or the larvae once they’ve found their way to your bloodstream so try to talk your people into getting you on it as soon as possible, especially since the arid region called North Texas earlier this year resembled the Okefenokee Swamp.

Heartworms—they’re not just for dogs anymore. Demand equal time. If your humans have their dog on heartworm preventative, you need to be on it too.

For more information about heartworms in kitties check out www.knowheartworms.com and www.vetmed.auburn.edu/distance/cardio/all.html.

Thanks to Drs. James Richards, Jane Brunt and Tom Nelson for their help in writing this column. Also thank you to www.knowheartworms.com for the use of the heartworm incident map.