The worms enter the cat by being ingested. Once in the intestines, the worms find the cat’s bloodstream and travel to the lungs. This journey takes approximately 8 or 9 days. The worms mature in the lungs and lay their eggs in lung tissue and airways. After the larvae hatch, they travel up the trachea, where they are swallowed by the cat and flushed through the digestive tract. About 40 days after the initial infection the larvae exit the cat through its feces. While in the lungs, these worms have a tendency to cause infection and damage tissue, primarily in the lower respiratory tract. Veterinary assistance is needed to eradicate a lungworm infestation.

Lungworms are hair-shaped worms that generally range from one to four centimeters in length. The females are significantly longer than the males. Two species of this worm are able to infect cats. Aelurostrongylus abstrusus , also known as Feline Lungworm, is the most common lungworm found in cats. Eucoleus aerophilus (sometimes called Capillaria aerophila) is a lungworm found in both cats and dogs. These worms were at one time thought to rarely affect cats, but after recent study, it is believed over five percent of all cats carry lungworm. 

Many cats show no symptoms when infected with lungworms. In young cats, cats with weakened immune systems, and in cases of extreme infestation, the following symptoms may be seen: 

Cats contract lungworm mainly from hunting and exploring outdoors. Adult worms can live for over 9 months in a hospitable environment. Both types of lungworm have different ways of entering the cat.

These worms infect slugs and snails. Cats come in contact with the worms by eating any small animal (birds, rodents, amphibia or reptiles) that feed on affected slugs and snails, or by eating the slugs themselves.

This type of worm mainly infects earthworms and rodents. The larvae spread from these hosts and live in small water pools. A cat can contract these worms from eating infected rodents or drinking contaminated water. 

Upon arrival at your veterinary clinic, the vet will request your cat’s full medical history. Then, a physical exam will be performed. The vet will take note of any symptoms that match signs of lungworm. The most common way to confirm an infection of lungworms is to test the cat’s feces for the presence of larvae. As it takes over a month for the larvae to pass through the cat, sometimes multiple fecal exams may be required. 

In some cases, a tracheal wash may be done to find larvae that have traveled to the trachea from the lungs. X-rays can be done to evaluate the condition of the lungs and to rule out any other causes of lung problems. A bronchoscopy may be used to get a visual on the cat’s airways. Often, the diagnosis may be made after a round of antibiotics has had no effect on the condition of the cat. It is important to note that in the case of kittens, a diagnosis needs to be made fast as the infection can be life-threatening. 

Lungworms can generally be eliminated through extensive treatment with medications. Your veterinarian will recommend the best type for the cat’s specific infection.

Many deworming medications are available for prescription through a veterinarian. To ensure all lungworms are exterminated, often the medication will be needed for up to two months. The treatment must specifically treat lungworm; not all do.

If the cat has developed a secondary infection from the lungworms, such as bacterial pneumonia, antibiotics will be prescribed for 2-4 weeks.

If any inflammation has occurred due to lungworm infestation,corticosteroids may be used to decrease it. 

Most cats make a full recovery from a lungworm infection. Kittens are at a higher risk for developing complications from lungworms that can become life threatening. If secondary infections have progressed, they need to be managed immediately before they become a threat to the cat. 

If at all possible, keep your cat indoors to prevent the possibility of infection. If a cat cannot hunt, the chance of it contracting lungworms is almost nonexistent. Maintain a regular deworming schedule through your vet. Clean the cat’s litter box daily, and disinfect it often. It is rare that lungworm can spread to humans, but not impossible.