If your cat is having difficulty breathing and experiencing coughing fits, lungworms could potentially be the cause. Although lungworms are relatively uncommon in cats compared to intestinal parasites, if they're contracted, they can negatively impact your cat's health. Therefore, it's important to understand what these microscopic invaders do. Read on to learn more about what lungworms are and what cat lungworm treatment would consist of.

Understanding Lungworms in Cats

According to CriticalCareDVM, lungworms are parasites that live in and negatively impact the respiratory system of cats. Roundworms are the most common type of lungworm seen in cats, the two main species seen being Eucoleus aerophilus and Aelurostrongylus abstrusus.

  • Eucoleus aerophilus: This species lives in the windpipe (trachea) and large airways. Cats become infected with Eucoleus aerophilus by accidentally consuming parasitic eggs or larvae.
  • Aelurostrongylus abstrusus: This species lives in the lungs, and it can infect cats if they have eaten a bird, rodent, frog or lizard that has recently eaten a snail or slug that contains the worms.

When a cat ingests the larval or egg stage of a worm, the larva develops in the intestine, migrates out of the intestines through the bloodstream and travels to the lungs, where it develops into an adult and lays more eggs. The eggs then hatch into larvae which are coughed up, swallowed and passed out in the feces where they are eaten by snails and slugs, and the cycle starts all over again.

Cats that hunt or scavenge, roam freely or live in multi-animal households are at higher risk for contracting lungworms than other cats.

Identifying the Clinical Signs

Clinical signs of lungworms in cats are usually related to the respiratory tract and associated with bronchitis or pneumonia. Some of these signs may include:

  • Coughing (which may look like retching or attempting to vomit)
  • Fast or abnormal breathing patterns
  • Pale gums
  • Wheezing
  • Nasal discharge
  • Increased sleep
  • Decreased energy
  • Decreased appetite

You may also find your cat hiding more, grooming less, or not wanting to jump or play like they normally do. In some cases, lungworms in cats may cause no signs at all and may only be diagnosed during a routine annual fecal exam by your veterinarian.

Diagnosing Lungworms in Cats

If your cat has any of the signs listed above, contact your vet to have your cat examined. It is likely that your vet will want a sample of your cat's feces so that it can be checked for worm eggs or larvae.

Your vet will conduct a full physical examination, and depending on what they learn, they may then recommend additional testing, which can include fecal exams to look for parasites or eggs, bloodwork to check for signs of infection and an evaluation of internal organ function.

In some cases, additional testing may be necessary to perform an inspection of the airways with a video camera (endoscopy), testing a sample of fluid from the lungs and following up with chest X-rays. Diagnosing a lungworm infection can be challenging for your vet because lungworms rarely shed their eggs in feces; therefore, patience and multiple fecal exams may be required.

A diagnosis of lungworms in cats is neither a life-threatening nor contagious situation. Because of this, cats that are suspected to have a lungworm infection are usually treated as outpatients. Still, it's recommended that you wear gloves while cleaning their litter box until your vet gives you the all-clear.

Cat Lungworm Treatment and Prevention

Treatment for lungworms is two-fold: Support the cat while they heal, and eliminate the parasite. Ivermectin and fenbendazole are the most common medications used to treat lungworms in cats. Topical treatments with selamectin have also been used. When treating a cat for lungworms, patience is advised. It may require up to two months of treatment to completely eliminate the infection.

If your cat has lungworms, the prognosis with treatment is usually excellent; however, the prognosis depends on the amount of damage done to the lungs as well as the age and health history of the cat. Kittens and cats with compromised immune systems are at the highest risk for developing issues with a lungworm infection, and chronic infections can cause significant inflammation in the lungs, leading to irreversible damage. To enable a full recovery, have your cat treated early.

The best way to prevent lungworms in cats is to prevent your cat from hunting or scavenging. If that's not possible, then having your cat's feces checked every six months for parasites is a good alternative. Otherwise, speak to your vet about other preventive measures to keep your cat free from internal parasites.

While lungworms can be difficult to treat, the good news is that they are relatively rare, and by working with your vet, you can maximize your cat's health and well-being — all while keeping them free of parasites.

Dr. Sarah Wooten Dr. Sarah Wooten

Dr. Sarah Wooten graduated from UC Davis School of Veterinary Medicine in 2002. A member of the American Society of Veterinary Journalists, Dr. Wooten divides her professional time between small animal practice in Greeley, Colorado, public speaking on associate issues, leadership, and client communication, and writing. She enjoys camping with her family, skiing, SCUBA, and participating in triathlons.

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