In dogs, Oslerus osleri is the parasite that commonly causes lungworm infection. They are prevalent in most parts of the world including many European countries, South Africa, Australia and New Zealand as well as in the United States. The upper respiratory tract, especially the trachea is where the adult forms of this nematode occur. The eggs laid by the parasite are hatched immediately and they are coughed up and then ingested by the dog to be later excreted in the feces. They can infect other dogs that come in contact with the feces but other animals or people are not usually affected. The larvae can be passed on to puppies when they are licked by a mother carrying the larvae in her saliva.
Lungworm infestations can be nearly asymptomatic and often go unnoticed. The most common symptom is a persistent dry cough that can vary in intensity from mild to severe, often accompanied by slightly raised respiratory rates. Other signs of respiratory distress may be present, but fatality from lungworm infection is rare. When dogs are infected by certain other types of nematodes such as Dirofilaria immitis and Angiostrongylus vasorum that usually live in the chambers of the heart, they may show symptoms of heart and lung syndromes combined.
The symptoms as well as known patterns of transmission may help diagnose lungworm infection. The detection of lungworm larvae in the dog’s feces confirms the infestation but all the infected dogs may not have them, or their number may be too few to be found in the feces sample examined. The veterinarian may do an x-ray and a bronchoscopy using the endoscope to examine the upper respiratory tract and to get washings of the trachea to check for lungworm larvae or eggs.
Suitable antiparasitic medications are effective in treating lungworm infection, but it is rather difficult and time consuming. The drug therapy needs to be continued for two months or more. Treatment is more effective in eliminating the infection when the nodules in the trachea are surgically removed concurrent with the administration of antiparasitic drugs and antibiotics.
Other lungworms affecting dogs
A parasite called Capillaria aerophila that usually occur in the nasal cavities, sinuses, bronchi and trachea of foxes can be transmitted to dogs too. When the eggs produced by the female worms living in the lungs get coughed up and swallowed they are excreted in the feces. The infection gets transmitted to the dogs when they drink the water contaminated with the feces of infected animals. When the eggs containing the larvae reach the intestine of the dog, they hatch there and later reach the liver through the blood vessels. The larvae take 40 days to reach maturity. Persistent sneezing accompanied by a discharge from the nose and chronic cough are the usual symptoms. Antiparasitic drugs can effectively eliminate the infection in dogs.