Borrelia Burgdorferi as a Cause of Fatal Necrotizing and Lymphoplasmacytic Myocarditis in a 6-Year-Old Female Labrador Retriever Dog
Faculty Mentor
Oscar Illanes
Area of Research
Veterinary Medicine
Major
Veterinary Medicine
Description
A 6-year-old female (spayed) Labrador Retriever was submitted for necropsy after a fatal cardiopulmonary event. Most significant post-mortem findings were confined to the thoracic cavity. The lungs were enlarged, moist, diffusely red, and pliable, with subtle rib impressions more prominent on the caudal lobes. Sanguineous frothy fluid was present within the trachea and bronchi. The right ventricle was enlarged and presented multifocal, slightly shallow areas of reddish-brown discoloration, up to 1.5 cm in the largest dimension, on its epicardial surface. These foci, surrounded by poorly defined areas of pallor, were also found within the endocardium and extended deep into the underlying myocardium. Microscopically a severe necrotizing lymphoplasmacytic myocarditis with interstitial fibrosis was seen. Borrelia burgdorferi antigens were detected by immunohistochemistry (Rabbit anti Borrelia burgdorferi antibody) within the areas of myocardial inflammation. Lyme disease is endemic in the northeastern United States, and although seroprevalence in dogs from endemic areas is high, the disease is often subclinical. Clinical disease, when present, is manifested primarily by arthritis and nephritis. Lyme disease induced myocarditis in dogs, reported primarily in Europe, seems to be a rare occurrence. Lymphoplasmacytic myocarditis in this species is often interpreted as non-specific and likely the result of virus infections, mainly by canine parvovirus-2, canine distemper virus, or more rarely, West Nile virus. The finding of Borrelia burgdorferi antigens in the heart lesions of this dog suggests that Lyme disease associated myocarditis may be underdiagnosed and should be considered as a possible cause of heart disease in dogs from endemic areas.
Borrelia Burgdorferi as a Cause of Fatal Necrotizing and Lymphoplasmacytic Myocarditis in a 6-Year-Old Female Labrador Retriever Dog
A 6-year-old female (spayed) Labrador Retriever was submitted for necropsy after a fatal cardiopulmonary event. Most significant post-mortem findings were confined to the thoracic cavity. The lungs were enlarged, moist, diffusely red, and pliable, with subtle rib impressions more prominent on the caudal lobes. Sanguineous frothy fluid was present within the trachea and bronchi. The right ventricle was enlarged and presented multifocal, slightly shallow areas of reddish-brown discoloration, up to 1.5 cm in the largest dimension, on its epicardial surface. These foci, surrounded by poorly defined areas of pallor, were also found within the endocardium and extended deep into the underlying myocardium. Microscopically a severe necrotizing lymphoplasmacytic myocarditis with interstitial fibrosis was seen. Borrelia burgdorferi antigens were detected by immunohistochemistry (Rabbit anti Borrelia burgdorferi antibody) within the areas of myocardial inflammation. Lyme disease is endemic in the northeastern United States, and although seroprevalence in dogs from endemic areas is high, the disease is often subclinical. Clinical disease, when present, is manifested primarily by arthritis and nephritis. Lyme disease induced myocarditis in dogs, reported primarily in Europe, seems to be a rare occurrence. Lymphoplasmacytic myocarditis in this species is often interpreted as non-specific and likely the result of virus infections, mainly by canine parvovirus-2, canine distemper virus, or more rarely, West Nile virus. The finding of Borrelia burgdorferi antigens in the heart lesions of this dog suggests that Lyme disease associated myocarditis may be underdiagnosed and should be considered as a possible cause of heart disease in dogs from endemic areas.