Researchers funded by the Morris Animal Foundation have discovered a new non-cancerous syndrome called polyclonal B‐cell lymphocytosis in some English bulldogs that were misdiagnosed with a common form of canine cancer.
The findings have been reported in the Journal of Veterinary Internal Medicine.
"This could save some dogs from being misdiagnosed, treated for cancer or even euthanized when they shouldn't be," said Dr Anne Avery, Professor of Immunology at the Department of Microbiology, Immunology, and Pathology at Colorado State University in a press release. "The dogs may look to their veterinarians like they have leukemia, based on original diagnostics, but they don't actually have cancer."
In earlier findings published by Dr Avery's team investigating B-Cell Chronic Lymphocytic Leukemia (BCLL), the team assessed which dog breeds had an increased risk for the BCLL cancer type. One of the breeds that were identified as at-risk were English bulldogs, however, the findings revealed that these dogs had a completely different presentation with this cancer. The dogs were much younger compared to other breeds, and they had very specific changes in their B-cells (important cells for immune function and antibody production, which are normally elevated in this cancer).
The researchers used a technique called flow cytometry, a method to identify specific characteristics of a population of cells. They found that the B-cells of some English bulldogs had differences on their surfaces compared to B-cells from other dog breeds, which led the reachers to wonder if these dogs truly had BCLL, or a different unidentified but related syndrome.
Following up on their original study, the researchers then assessed 195 English bulldogs in a BCLL cohort study, looking at the blood constituents of these dogs.
The researchers speculated that if B-cells in these bulldogs were all identical, they likely originated from the same original B-cell that would have been triggered by BCLL cancer. However, if these B-cells were different in characteristics, it may not be BCLL cancer that triggered their production, but something else instead.
The findings from the flow cytometry data identified 83 out of the 195 dogs that had changes in their B-cells that deviated from what they expected. Out of the 83 dogs with changes, 58 dogs had very specific differences in their B-cell production, suggesting that these B-cells were not a result of BCLL cancer. The researchers also highlighted that these dogs tended to be young, between one and two years old. Three-quarters of the dogs were male, and many of the dogs had enlarged spleens and increased antibodies in their blood, which the researchers speculated may be as a result of a genetic origin in these English bulldogs.
This led the researchers to conclude that 70% of the dogs originally diagnosed with BCLL in the cohort study in fact had this newly identified syndrome.
"This important finding demonstrates that we shouldn't assume that a high B-cell count always indicates cancer in English bulldogs," said Dr Janet Patterson-Kane, Morris Animal Foundation Chief Scientific Officer. "This is very important information for veterinarians who may initially see these patients in their clinic."
According to Dr Avery, the new findings clarify their previous work on BCLL. They suggest that rather than English bulldogs being at higher risk of the cancer, the dogs actually develop a non-cancerous syndrome that has many similarities to leukemia but does not have a malignant clinical outcome. Furthermore, the syndrome seems to have a genetic origin in English bulldogs and does not seem to affect other dog breeds. More research is required to confirm these findings and to help identify a gene that might be involved in the susceptibility for the syndrome in some English bulldogs.