08/13/2026
How do you treat lungworm?
Cat rescue is such an interesting arena – depending on which part of it consumes you, there will be things that are, to you, obvious and common place; to another, it is something completely unheard of! For many, lungworms fit that category. If you are one who has not encountered them before, let us tell you what we learned this time around!
Lungworms – what are they? Aelurostrongylosis abstrusus (the most common lungworm in cats) is a nasty little worm that cats can get when they eat slugs and snails, or the creatures that eat those slugs and snails - rats, mice, lizards, frogs, and birds; also appears it can be passed to kittens via the placenta or through milk during nursing. From the intestines, the larva migrates via the bloodstream to the lungs, and the larva live there until they become adults ; the adults lay their eggs in the lungs where they hatch, migrate through the lung tissue, are coughed up and swallowed – and are passed out through the f***s into the environment where they enter slugs and snails… and it starts all over. (which came first, the chicken or the egg…)
A cat gets the lungworm through eating the host of the worm (although pregnant and nursing cats can transfer the worm to the kittens), but one study estimated up to 50% of free roaming cats were infected with lungworms. What is important to know is that it is rarely fatal in cats – but the adult worm can live in the lungs for up to 2 years, and the cat can be shedding the larva for that length of time. Like most infections and problems facing cats, it is the kittens, the seniors and the immune compromised who are most at risk for complications.
While fenbendazole (Panacur) has been routinely used for treatment – and is successful – the problem can lie in the life cycle of the worm. The 3 days at 50 mg/kg dose (some say 5 days, some say 14, or 21…) may be ineffective over the long run. Reading the links listed below was eye-opening, because it is very difficult to find a consistent dose regimen for any one product. Happily, it does appear the topical medications ARE effective – the problem is finding the length of treatment needed. Advantage Multi has been shown to be effective, but it does look like 2 doses are needed, 2 weeks apart. Revolution is effective, dose recommendations though seem to vary. At one large site the trappers used Profender, because it appears a single dose may be effective, though a repeat dose in 30 days may be given as a precaution. They chose the Profender because they were treating the entire colony; with several cats displaying respiratory symptoms, and the history of lungworm in the colony, plus the inbreeding with the moms likely transferring to the kittens… it just made sense. The trappers would not be able to retreat these cats, and wanted to ensure a best chance scenario for total health.
The take away – lungworms can cause respiratory problems, but are rarely fatal, and can be treated with topical medications. To prevent this occurrence in kittens… TNR! Make sure those cats are spayed/neutered, prevent more babies, prevent more suffering! It’s worth it!
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4936016/
Lungworms in Cats: What Are They, and How Do You Treat Them? | PetMD
