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Lungworms in Dogs

What Are Lungworms in Dogs?

Lungworms are a type of parasite that can infect the airways and lung tissue of both domestic and wild dogs, comprising various species of worm parasites, including roundworms (nematodes) and flukes (trematodes). While roundworms can be found universally without specific geographical constraints, fluke lungworms tend to be more prevalent in certain environments.

For instance, the lung fluke Paragonimus kellicotti is predominantly found in regions such as the Great Lakes area, the Midwest, and the Southern United States. This distribution is due to the fact that the fluke lungworm relies on particular species of snails and crayfish, which serve as intermediate hosts during specific phases of its life cycle, and are commonly found in these regions.


Symptoms indicating the presence of lungworms in dogs may encompass:

  • Non-productive cough (not accompanied by mucus production)
  • Elevated respiratory rate
  • Reduced exercise tolerance (manifesting as difficulties in playing as vigorously or for as long as usual)
  • Breathing difficulties

Additionally, dogs may exhibit subclinical lungworm infections, where they do not display any observable signs of illness.


Lungworms in dogs typically result from the ingestion of lungworm larvae. Additionally, puppies can acquire larvae from their mother through grooming and nursing practices. The immature larvae enter the gastrointestinal (GI) tract, penetrate the intestinal wall, and then enter the circulatory system (either blood or lymphatic), eventually reaching the heart and lungs.

Depending on the lungworm species, larvae can mature into adult worms within as little as 5 weeks after being ingested by a dog. However, in certain lungworm species, the maturation process may take up to 21 weeks. Female adult lungworms begin laying eggs, which hatch into first-stage larvae within the airways. These larvae, along with the eggs, are expelled through coughing and may be spat out or vomited by the infected dog.

Dogs that come into contact with the infected dog’s saliva or vomit can contract lungworms. Moreover, if the infected dog ingests its own spit or vomit, the lungworm eggs and larvae travel through the GI tract and are subsequently shed in the feces. Other dogs that encounter this contaminated feces can become infected.


Veterinarians typically diagnose lungworms in dogs by conducting chest x-rays, especially if the pet has a history of respiratory issues. They also collect fecal samples and might suggest an airway wash if they are unable to confirm the diagnosis through other means.


In dogs with lungworms, x-rays may reveal small areas of inflammation within the lung tissue or larger regions with signs of pneumonia. Severe lung damage can lead to a pneumothorax, where air leaks into the dog’s chest cavity. Additionally, one type of lungworm can cause thickening of the large tracheal wall (windpipe) and the development of abnormal tracheal nodules, which may be visible on x-rays.

However, x-rays alone cannot definitively diagnose lungworms in dogs, as other illnesses can produce similar effects. Nonetheless, based on factors such as geographical location or recent travel history with the dog, the veterinarian may suspect lungworm infection.

Fecal Tests

To detect lungworms, your veterinarian will utilize fecal tests to identify eggs and larvae. They might request multiple fecal samples from different days since the shedding of lungworm eggs and larvae in the feces can vary intermittently.

Airway Wash

If x-rays and fecal testing don’t provide a definitive diagnosis of lungworms, your veterinarian might suggest an airway wash, such as a transtracheal wash (TTW) or bronchoalveolar lavage (BAL). These procedures are conducted under anesthesia. The fluid collected from your dog’s airways and lungs during the wash can contain lungworm larvae, eggs, and inflammatory cells, aiding in the diagnosis process.


Treating lungworms in dogs typically involves administering a dewormer orally for a duration of 14 days. In response to the deceased worms and larvae, your dog’s immune system may trigger inflammation, for which your veterinarian might prescribe a corticosteroid anti-inflammatory medication.

During the initial phase of treatment, dogs may appear to worsen as a result of the significant number of dead or dying worms. Should you have concerns about your dog’s condition or queries regarding the treatment, it’s advisable to contact your veterinarian for potential additional interventions.

In more complex cases of lungworm infection, cysts may develop in the lung tissue. If these cysts rupture, your dog could accumulate air in the chest and around the lung, leading to a condition known as pneumothorax. In instances where breathing becomes difficult due to air accumulation, your veterinarian may need to alleviate the air pressure and insert a chest tube until the air leak resolves on its own.

In rare scenarios, surgery might be necessary to close the areas where air is escaping from the lung tissue. Without treatment, severe lung inflammation and damage can lead to fatal outcomes.

Living and Management

The majority of lungworm cases in dogs can be managed successfully with medical treatments, typically without the need for surgery. To assess your dog’s progress during treatment, your veterinarian may request additional fecal samples to monitor the presence of lungworm larvae or eggs.

If abnormalities were detected on the initial x-rays, your veterinarian might recommend follow-up imaging to evaluate the changes in the affected areas post-treatment. Scarring of the airways can be a potential complication of lungworm infestation, which may manifest as coughing or asthma-like symptoms, necessitating long-term management.

For dogs requiring surgery, a longer recovery period is expected. Depending on the duration of chest tube placement and the extent of lung surgery performed, recovery can span from 4 to 6 weeks.

Lungworms in Dogs FAQs

How does a dog get lungworms?

Dogs become infected with lungworms by ingesting lungworm eggs and/or immature larvae. Once inside the gastrointestinal tract, the larvae penetrate the intestinal wall and migrate to the dog’s airways and lung tissue, where they reside and reproduce. The eggs and larvae present in the airways are expelled through coughing and may be spat out or swallowed by the dog, leading to reinfection.

Can you see lungworms in dog poop? 

No, lungworm eggs and larvae are not visible to the naked eye in dog feces. Your veterinarian can detect both by examining your dog’s fecal sample under a microscope.

Can humans get lungworms?

No, humans cannot contract lungworms.

Nevertheless, it remains crucial to ensure your dog receives regular deworming (once or twice a year), as certain worm parasites can pose health risks to humans.

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