Lungworm infection has become an increasing concern for dogs in Ontario as a cause for chronic respiratory disease with signs such as coughing, gagging, lethargy, exercise intolerance and difficulty breathing. Initially primarily a problem in Atlantic Canada where an estimated 21% of dogs presenting with signs of chronic respiratory disease are infected with Fox Lungworm, it has now spread with several documented cases in Ontario.
The two species of concern in Canada are the Fox Lungworm and the French Heartworm. So far the Fox Lungworm is of greatest concern to Ontario dogs. Foxes, coyotes and raccoons are all hosts to this parasite and their close proximity to urban areas increases the risk of parasite transmission to our pet dogs.
Snails, slugs and their mucus play an important part in the transmission of the disease. Dogs become infected by ingesting lungworm larvae found within snails or slugs themselves or by vegetation exposed to snail mucus (which contains infective larvae), contaminated outdoor water bowls or dog toys, or by drinking from contaminated puddles.
Once the larvae are ingested by a dog they migrate from the gut, through the liver and into the blood vessels that return blood to the right side of the heart. From here the heart pumps the larvae into the lungs where they mature into adult Lungworms. The adults then lay eggs into the small airways of the lungs and when they hatch small L1 larvae are then coughed up by the dog and swallowed. These new young larvae are passed in the feces into the environment where snails and slugs consume the infected feces and the larvae mature to a stage where they can infect a new dog, fox, coyote or raccoon.
Infected wildlife or dogs will quickly contaminate their environment with many lungworm larvae increasing the risk for reinfection or for infection to others.
Once a dog is infected they are likely to start coughing or gagging. This cough may become chronic and some dogs may have difficulty breathing. Fortunately, there is an approved treatment and prevention product available from your veterinarian by prescription. Please talk to your veterinarian or drop in at the College Manor Vet Hospital about your dog’s risks for this parasite as well as how you may protect them from this and other nasty parasites this coming season.