Paragonimus kellicotti is a lung fluke that was first discovered in Kentucky and is commonly known as the North American lung fluke. Originally found only in North America, this lung fluke is now widespread, with cases as far as the Middle East. P. kellicotti, like many lung fluke species, depends on hosts for survival. This lung fluke has three main stages, involving three different hosts. In dogs, the adult P. kellicotti infect lung tissue and, without treatment, can result in death.
P. kellicotti eggs hatch in water. The hatchling, or miracidium, searches for and infects water snails where they develop sporocysts and redia. From this, cercaraie develop and leave the snail. At this point, they search out a crustacean, such as a crab or crayfish, then enter the heart, liver or muscles and wait for the final host. When a dog, human, cat, raccoon or other mammal eats the crustacean, the flukes enter the intestinal tract. From here, they move through the walls of the intestine, making their way into the lung tissue.
Some dogs can have lung fluke infections and show no symptoms, with the flukes dying off without treatment. Others will have deep coughing, shortness of breath, rapid heart rate, weakness and lethargy. As the infection worsens, complications include pneumothorax, or a collapsed lung, bronchiectasis, or the permanent narrowing of air passageways in the lungs, and hemoptysis, where your dog coughs up blood.
If your veterinarian suspects an infection with P. kellicotti or other lung fluke, he will examine your dog’s feces or sputum, looking for fluke eggs that have passed through the system. X-rays can determine where in the lungs the flukes have infected, as well as the extent of the infection. Another diagnostic test often performed is a tracheal wash. For this procedure, your dog undergoes anesthesia or sedation before the veterinarian inserts a catheter into the mouth and down the airway. A small amount of fluid is pushed into the airway before being aspirated back out for analysis.
If tests reveal your dog is infected with P. kellicotti and he is showing symptoms, your veterinarian will prescribe antiparasitic medications, such as praziquantel, albendazole or fenbendazole. These medications are administered orally, anywhere from 3 to 14 days.
- University of Michigan Museum of Zoology: Paragonimus Kellicotti
- University of Pennsylvania School of Veterinary Medicine: Paragonimus Kellicotti Homepage
- Companion Animal Parasite Council: Intestinal Parasites, Parasites of Other Systems -- Trematodes
- VetInfo: Bronchiectasis in Dogs
- PetCare Vet: Hemoptysis (Coughing Blood) in Dogs and Cats
- The Merck Veterinary Manual: Lung Flukes in Small Animals
- American College of Veterinary Internal Medicine: Tracheal Wash and Bronchoscopy
- University of Pennsylvania School of Veterinary Medicine: Fenbendazole
- University of Pennsylvania School of Veterinary Medicine: Praziquantel
- Jupiterimages/liquidlibrary/Getty Images