Parasitic Infection of the Respiratory Tract in Dogs

By PetMD Editorial on Aug. 31, 2009

Respiratory Parasites in Dogs

Respiratory parasites can be classified as worms, or as insects such as maggots or mites that live in the respiratory system. They can be found in the passages of the respiratory tract or in the blood vessels, including the upper respiratory tract (nose, throat, and windpipe), or the lower respiratory passage (bronchi, lungs).

Such parasites can affect all of the host’s systems: the respiratory system, the cardiovascular system (the heart), the circulatory system and the endocrine system (the liver and kidneys).

Households with multiple pets, and dwellings in which animals are living in unsanitary conditions have a higher risk of transmission. Exposure to the infected feces of other animals that are carriers of the parasite can also make an animal more susceptible. This can include being in an environment such as a shelter or boarding facility, but your dog is also more at risk if it goes outdoors frequently, as it has more opportunities to come into contact with other animals and their feces and urine. Sporting dogs are also at increased risk, due to exposure to wild animals and their droppings in wooded areas, and to water borne parasites in rivers and lakes.

These parasites often begin their life cycles in shellfish, crabs, lizards, and worms, spreading to other animals opportunistically.

Symptoms and Types

  • May show few or no signs
  • Sneezing
  • Runny nose
  • Bloody nose
  • Wheezing
  • Harsh lung sounds
  • Behavior changes (brain migration of parasites)
  • Coma (brain migration of parasites)


  • Eating earthworms
  • Digging or sniffing around rodent burrows
  • Touching noses and/or other mucous membranes with infected cats or dogs
  • Being sneezed upon by an infected animal
  • Eating infected rodents
  • Eating infected martens and mink or being exposed to their feces
  • Eating infected birds
  • Eating sheep offal
  • Eating infected crayfish
  • Eating snails (uncooked)
  • Eating infected ants
  • Eating infected cockroaches
  • Exposure to infected feces of other cats and dogs
  • Puppies can be infected from mother’s milk while nursing if the mother is infected


You will need to give your veterinarian a thorough history of your dog's health and recent activities, including recent history of boardings, outings, and experiences with other animals or with pests. Your veterinarian will then perform a complete physical exam on your dog. Standard laboratory work will include a blood chemical profile, a complete blood count, an electrolyte panel and a urinalysis in order to determine the exact origin of the symptoms. A differential diagnosis may find parasites, but it may also find a bacterial respiratory infection.

Your veterinarian will specifically examine your dog's urine and feces for parasite eggs or pieces of parasites. In feces, these are found by microscopically examining a solution of your dog's feces. A sample of sputum (cough discharge) can also be microscopically examined for parasite eggs.

X-ray imaging of the lungs is crucial for visualizing abnormal lung changes that may be indicative of a parasitic infestation. A rhinoscopy or bronchoscopy (direct visualization of the nose and bronchioles with a small camera) is an even better way to look for respiratory parasites.


Patients with respiratory parasites are usually treated on an outpatient basis with dewormers. Anti-inflammatory agents are also given to the patients to decrease their body’s negative immune reaction to so many dead parasites. In some cases, the parasites can only be removed surgically one at a time.

If your dog is having trouble breathing, it should be hospitalized and given oxygen therapy until the parasite infestation has been resolved.

Living and Management

Your veterinarian will schedule follow-up appointments to examine your dog's respiratory passages with a bronchoscope and to reexamine fecal and urine samples for parasite eggs. Preventing your dog from eating insects, rodents, and wild animals is the best way of protecting your dog against parasite infections. Also, avoiding contact with unknown cats and dogs, or even separating your own pets (if you have others) when they appear to be ill are some ways in which you can prevent or mitigate a parasitic infection.

There may be some more preventive methods for avoiding parasites. If your dog is a sporting dog, or if you live in a wooded area, or near a body of water, talk to your veterinarian about the local parasites and what you can do to protect your dog from an infestation.

Most animals recover well from respiratory parasites, unless the infection has been chronic (long term). If parasites have migrated to the brain, causing your dog to show symptoms of neurological impairment, a cure will not be possible.

If you suspect that your dog is infected with parasites, schedule an appointment with your veterinarian as soon as possible. If your dog has already begun to show symptoms of neurological change or degeneration, call your veterinarian for an emergency appointment.

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