Expression of Mutated BRAFV595E Kinase in Canine Carcinomas—An Immunohistochemical Study

Alterations of the <i>BRAF</i> gene and the resulting changes in the BRAF protein are one example of molecular cancer profiling in humans and dogs. We tested 227 samples of canine carcinomas from different anatomical sites (anal sac (<i>n</i> = 23), intestine (<i>n</i> = 21), liver (<i>n</i> = 21), lungs (<i>n</i> = 19), mammary gland (<i>n</i> = 20), nasal cavity (<i>n</i> = 21), oral epithelium (<i>n</i> = 18), ovary (<i>n</i> = 20), prostate (<i>n</i> = 21), thyroid gland (<i>n</i> = 21), urinary bladder (<i>n</i> = 22)) with two commercially available primary anti-BRAF^V600E antibodies (VE1 Ventana, VE1 Abcam). The immunohistochemical results were confirmed with droplet digital PCR (ddPCR). <i>BRAF^V595E</i>-mutated cases were found in canine prostatic (16/21), urothelial (17/22), and oral squamous cell carcinomas (4/18), while other carcinoma types tested negative. Both antibodies showed consistent results, with intracytoplasmic immunolabeling of tumour cells, making them reliable tools for detecting the <i>BRAF^V595E</i> mutation in canine carcinomas. In conclusion, identifying <i>BRAF</i> mutations from biopsy material offers a valuable opportunity to enhance cancer treatment strategies (BRAF inhibitors) in canine urothelial carcinomas, prostatic carcinomas, and oral squamous cell carcinomas.