Lungworm in Dogs: Everything Pet Parents Should Know

Lungworm in dogs is a parasitic infection that affects the lungs and airways, often causing a persistent cough and breathing problems. While some dogs show mild or no symptoms, others can develop serious respiratory issues that require prompt veterinary care. 

Dogs typically get lungworm by ingesting contaminated food, water, or parasites like slugs and snails. Because it can be mistaken for common conditions like kennel cough, ongoing coughing or exercise intolerance should always be evaluated by a veterinarian. 

What Is Lungworm in Dogs?

Lungworm in dogs occurs when multiple species of worm parasites infect the different areas of the airway in dogs.  

 In the United States, the tracheal worm (Oslerus osleri) is the most common cause of lungworm infections in dogs. This worm causes pink nodules in the throat that have the adult worm inside.  

Lungworms are common in certain environments and depending on the underlying cause, can take some time to grow and cause symptoms.  

Lungworm in dogs can even be an incidental finding in a clinically normal dog.  

Commonly confused for kennel cough, lungworm also causes a very persistent cough that requires immediate medical attention. 

Symptoms of Lungworm in Dogs

Signs of lungworm in dogs can include: 

• Dry cough (no mucus) 

• Rapid respiratory rate 

• Exercise intolerance (becoming out of breath more easily, not able to play as hard/long as usual) 

• Difficulty breathing 

Dogs can also have a subclinical lungworm infection—meaning there will be no symptoms. 

Causes of Lungworm in Dogs

Depending on the specific parasite causing lungworm in dogs, they can obtain this disease in a variety of ways. 

Lungworm can be spread commonly from dog to dog by infected saliva or feces.  

Infected dogs cough up and then swallow lungworms that are then passed in the stool. This stool then contaminates the environment, where other dogs can ingest contaminated food or water and become infected themselves.  

Causes of lungworm in dogs: 

• Oslerus osleri (tracheal worm) 

• Crenosoma vulpis (fox lungworm) 

• Eucoleus aerophilus, also known as Capillaria aerophilus 

• Filaroides hirthi (canine lungworm) 

• Angiostrongylus vasorum (French heartworm) 

• Dirofilaria immitis (canine heartworm) 

• Angiostrongylus cantonensis (rat lungworm) 

How Veterinarians Diagnose Lungworm in Dogs

To diagnose lungworm in dogs, a vet will begin with a physical exam. They will then recommend X-rays. 

On these X-rays, vets might see small spots of inflammation within the lung tissue, or larger areas of inflammation with possible pneumonia. If the lung is severely damaged, it can break open and cause air to leak into the dog’s chest. This is called a pneumothorax.  

One species of lungworm can produce thickening of the large trachea wall (windpipe) and/or trachea nodules (abnormal trachea growths), which your vet may also be able to see. 

X-rays alone can’t be used to diagnose lungworms in dogs, as other diseases can cause similar effects. A fecal analysis and heartworm testing are also important in all coughing dogs.  

However, your vet may have a suspicion of lungworm based on your geographical location and/or a history of recent travel with your dog. 

Other diagnostics your vet may recommend include: 

• Fecal tests 

• Airway washes: An airway wash (or transtracheal wash) is a procedure in dogs where saline is put into a dogs lungs while they are intubated under anesthesia. This saline is then quickly removed during this endoscopy procedure and the fluid is analyzed for lungworms or other abnormalities like inflammatory cells.  

Treatment for Lungworm in Dogs

Treatment of lungworm in dogs can be difficult to treat but involves a dewormer that’s usually administered orally.  

Fenbendazole and ivermectin are commonly used to treat dogs with lungworm. 

Your dog’s immune system will generate inflammation as a reaction to the dead worms and larvae, so your veterinarian may also prescribe a corticosteroid anti-inflammatory medication (prednisone or prednisolone).  

It’s common for a dog’s symptoms to seem to get worse when first starting treatment, since this is the period when there will be the largest number of dead or dying worms.  

If you are concerned with how your dog is doing or have any questions, call your veterinarian in case additional treatment is needed.  

In more complicated lungworm cases, cysts can form in the lung tissue. If the cysts rupture, your dog can accumulate air that’s in the chest and outside the lung (pneumothorax).  

If enough air accumulates to cause your dog to have difficulty breathing, your vet might need to remove the air and insert a chest tube until the air leak seals on its own. 

Rarely, surgery may be needed to close the sites where air is leaking from the lung tissue.  

Untreated cases where there’s severe lung inflammation and/or lung damage can result in a dog dying.  

Recovery and Management of Lungworms in Dogs

Most cases of lungworm in dogs respond to medical management alone.  

To monitor your dog’s response to treatment, your veterinarian will want to examine more fecal samples to see if any lungworm larvae/eggs are present. 

If your vet found abnormalities on the original x-rays, they might want to retake the images to see how the abnormal areas look after treatment. 

Scarring of the airway(s) is a possible complication of lungworm infestation. If the scarring results in coughing or other asthma-like signs, this may require long-term management. 

Dogs that need surgery will require more time for recovery and healing. Depending on how long chest tubes are in place and how extensive the lung surgery is, recovery can take four to six weeks. 

During your dog’s recovery, your vet may recommend Imuquin to boost your pup’s immune system.  

Prevention of Lungworm in Dogs

Prevention of lung worm in dogs should be something you discuss with your veterinarian—especially if you live in an area where lungworm is prevalent, such as the Southeastern states and the Gulf Coast.  

Angiostrongylus cantonensis is also common in Hawaii in puppies. 

In most cases, lungworm in dogs can be prevented with prescription heartworm medication given monthly. 

Prevention is also achieved by ensuring your dog is not eating things they should not, like dog feces and dirt. 

If you leave a water bowl in your garden for your dog, clean it often to remove any snail or slug mucin that’s been left behind. Not letting them carry sticks on a hike in an endemic area would also help avoid exposure to these creatures. Ensuring they stay away from playing with slugs and snails is an important step as well, as these can also carry canine lungworm.