A Rare but Aggressive Cancer with Breed-Specific Impact
Anal sacs (sometimes called anal glands) are small structures located just beneath the skin that store a strong-smelling fluid. In most dogs, they empty naturally during defecation. In some, they don’t empty as they should, leading to discomfort, impaction, infection, and familiar behaviors like scooting or the need for manual expression.
In rare cases, cancer can develop in these sacs. The most common form, anal sac adenocarcinoma, is particularly aggressive and has a high potential to spread.
While this cancer represents only a small fraction of tumors, its impact is felt far more strongly in English Cocker Spaniels. According to Dr. Shaying Zhao, Professor of Biochemistry and Molecular Biology at the University of Georgia, this breed is seven times more likely to develop the disease than other dogs. By the time it’s detected, it has often already spread.
This raised an important question: Could genetics be part of the story?
Exploring the Genetic Landscape of Disease
With support from the AKC Canine Health Foundation and the English Cocker Spaniel Club of America, Dr. Zhao and her team set out to investigate.
In an initial study, they analyzed DNA from approximately 50 dogs and identified three candidate genes potentially associated with anal sac adenocarcinoma in English Cocker Spaniels. Interestingly, some of the genes active in this cancer differ from those seen in other canine cancers.
Building on these findings, the current phase of research is focused on a critical distinction: whether these genetic variations are tied specifically to the cancer itself, the breed, or both, and whether they play a direct role in cancer development.
Dr. Zhao shared that while certain genetics appear to be associated with the tumor, more work is needed to determine which markers are reliable and how they might guide future research.
Progress Powered by Community and Commitment
This work is not driven by science alone—it is also driven by a deeply committed community.
English Cocker Spaniel breeders and dog owners have played an essential role, contributing specimens, traveling long distances to take part, and supporting ongoing data collection efforts. They’re united by the shared goal of better understanding this devastating cancer and advancing research toward meaningful solutions.
As Dr. Zhao emphasizes, progress in research often unfolds over time. Advances depend on sustained effort, collaboration, and resources.
As this study nears completion, the work continues, step by step. Researchers, breed clubs, and supporters remain focused on building a clearer understanding of the disease.
Each step forward brings us closer to a deeper understanding of disease and, ultimately, more good days for dogs and the people who love them.
To support continued genetic research, please visit akcchf.org/donate.
