When Worms Make a Home Out of Your Cat’s Lungs

Breathing Problems from Lungworms in cats


[From Tufts May 2012 Issue]

“It’s a little bit creepy,” says Catnip Editorial Board member Elizabeth Rozanski, DVM. “Larvae migrate from the intestine into the bloodstream and, from there, to the lungs, where they set up housekeeping. They get bigger, maturing into adult worms, and then lay more eggs, or larvae.” In the meantime, the worms can cause asthma-like symptoms — difficulty breathing, coughing, and, if things become severe enough, even emphysema, fluid in the lungs, or pneumonia.

Lungworm disease usually occurs in kittens, particularly kittens “from sketchy backgrounds,” says Dr. Rozanski — those who live almost entirely outdoors and eat whatever they can find. “We’ve treated two stray kittens over the last couple of months who were trying to fend for themselves completely.”

One of them was Esme, a stray found by a family on their porch in western Massachusetts during a freak snow, ice, and wind storm last Halloween weekend. Shivering, meowing, and hungry, Esme was brought by the family to the Cummings School, where you could see her respiratory effort was increased just by watching her sides.

Kittens tend to get lungworms by eating snails and slugs that are already infected with them. “While adult cats are effective hunters who can catch a mouse or bird and sometimes become infected that way,” Dr. Rozanski says, “kittens are not. But it’s easy for them to catch a slow-going snail or other slow-going animal. A couple of years ago, we took care of three kittens with lungworms found in an old, abandoned mill. The mill was by the water,” where snails are apt to hang around.

“It’s not going to happen in a house cat that eats Fancy Feast and never goes anywhere,” Dr. Rozanski says. “It’s almost entirely feral cats” — important for those involved in cat rescue or fostering stray kittens.

Once a kitten eats an animal infected with lungworms, specifically, a species of worm called Aelurostrongylus abstrusus, larvae from those worms make it down to the small intestine during digestion, then break through the intestinal wall and travel through the blood to the lungs. After the larvae mature into adult worms, more larvae, or eggs, are laid. Some of those larvae are either coughed up or swallowed. When swallowed, they might be eliminated from the cat’s body via bowel movements. Whether coughed up or voided, they can then infect yet another animal. The worms that remain in the lungs are the ones that wreak respiratory havoc.

A veterinarian will suspect lungworms if what seems like an upper respiratory infection in a kitten or young adult cat isn’t getting any better. She will also look for evidence of lungworms in the cat’s feces to help make a definitive diagnosis, along with performing a couple of tests.

Treatment is easy. A dewormer called fenbendazole eradicates the worms, and the kitten will then breathe easy, as they say. For severely affected cats, a corticosteroid or bronchodilator may be in order.

Esme, unfortunately, required a corticosteroid but came through her ordeal fine. In fact, she was adopted by Tufts client liaison Ellen Baker just after Thanksgiving. It was Baker who gave Esme her name.

“She’s delightful and sweet,” Baker says, “and has a best friend in the house,” a male cat named Omar. “They spend all day wrestling and playing,” she reports. “They love each other.”

It’s a story we like: one with a frightful beginning but a happy ending.


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