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Parasitic Respiratory Infections in Dogs

Lungworms are a parasitic worm (nematode) that settles in the lungs and windpipe (trachea), causing severe respiratory problems. Dogs that spend a lot of time roaming in the woods and/or on fields are at higher risk of developing this type of parasitic infections.

Symptoms and Types

There are several species of worm that can migrate to the lungs of animals, causing coughing and shortness of breath. The parasite most commonly seen in dogs is the Oslerus osleri.

Adult worms create nodules in the windpipe of the animal and lay eggs. The larvae that hatch cause reactions in the airways, leading to obstruction of breathing. Complications can lead to more serious problems such as shortness of breath (dyspnea), bronchitis, emphysema, fluid build-up in the lungs, and even pneumonia.

Signs are not severe unless there are large numbers of larvae living in the airways. Minor infections that do not cause any signs are also possible. Dogs that have been previously infected with lungworms have a degree of immunity and may be able to fight off a re-infection if the load is not too great.

Causes

Dogs become infected with lungworms when they drink water or eat prey infected with the larval stage of the worm. The larvae then migrate out of the intestines via the bloodstream to the lungs, where they develop into adult worms and lay eggs in the host's lungs. The eggs are then coughed up by the animal or passed in feces, which may then be eaten by birds, rodents, snails, or other pets.

Puppies may also become infected by their mother (dam) when they are licked by or ingest feces from the infected dog.

Diagnosis

Tests to check if a dog has a lungworm infection include:

• Physical examination (lung auscultation) and history
• Chest X-rays
• Fecal examination for eggs
• Complete blood count (CBC)
• Examination of fluid from lungs (tracheal wash)