Top Cancer in Golden Retrievers May Be Linked to Vector-Borne Bartonella Pathogen
The discovery of a potential link between the stealth bacterial pathogen Bartonella and hemangiosarcoma (HSA) is casting new light on the top cancer concern in Golden Retrievers. A vaccine to protect dogs against Bartonella infection could be key to decreasing the incidence of this highly malignant cancer.
“Bartonellosis is one of the most important emerging infectious diseases in humans and dogs,” says Edward B. Breitschwerdt, DVM, DACVIM, the Melanie S. Steele Distinguished Professor of Medicine and Infectious Diseases and co-director of the Vector Borne Disease Diagnostic Laboratory at North Carolina State University, where the discovery was made after 30 years of Bartonella investigations.
“If we could prevent a bacterial infection that can cause cancers such as hemangiosarcoma, it would be phenomenal,” says Ann Hubbs, DVM, PhD, chair of the Golden Retriever Club of America Health & Genetics Committee.
With one in five Golden Retrievers dying from HSA, the Golden Retriever Foundation is a dedicated champion sponsor of the AKC Canine Health Foundation’s Hemangiosarcoma Research Initiative. Since 1995, the Initiative has provided funding of $3.8 million for 27 research studies.
A study currently underway in Dr. Breitschwerdt’s laboratory at North Carolina State University is seeking to learn about the prevalence of Bartonella infection in dogs with splenic and cardiac HSA in different geographical locations of the U.S. This study builds on an earlier one in which the research team found a high prevalence of Bartonella infection in dogs from North Carolina with splenic HSA. These findings were published in the Journal of Veterinary Internal Medicine in 2011.
An early report based on the current study was published in PLOS ONE in January 2020. Using PCR analysis, the research team looked for Bartonella, Babesia parasites and Hemotrophic Mycoplasma bacteria in 110 dogs with HSA. Samples included fresh frozen HSA tissue, fresh frozen non-tumor tissue, and whole blood and serum banked at the Canine Comparative Oncology and Genomics Consortium. The samples were from 13 Golden Retrievers, 18 Labrador Retrievers, six German Shepherd Dogs, four Bichon Frisé, four Boxers, 34 other breeds, and 31 mixed-breed dogs.
“While 73 percent of all tissue samples from these dogs were positive for Bartonella DNA, none of the blood samples were, which indicates that whole blood samples do not reflect the presence of this pathogen,” explains Dr. Breitschwerdt. “The presence of Bartonella DNA in 57 percent of cardiac HSA tumors and in 93 percent of non-tumor cardiac tissue is an important finding. Why was Bartonella in cardiac tissue when the heart has no role filtering bacteria out of the circulation as does the spleen?”
Given the predisposition of Golden Retrievers to HSA and the toll of this cancer in the breed, urgency is warranted for research efforts to learn more about Bartonella and the chronic inflammation and tissue damage it causes. Efforts to protect dogs from ticks, fleas and other vectors that carry Bartonella remain important.
“An important contribution we can make to canine health is developing a vaccine to prevent infection with Bartonella,” Dr. Breitschwerdt says. “Dogs are our best sentinels to understand this insidious pathological bacterium.”