Clinical and Pathological Diagnosis of Hereditary Gastrointestinal Polyposis in Jack Russell Terriers

Hereditary GI polyposis in JRTs is a novel hereditary disease characterized by the development of solitary and multiple polypoid tumors, predominantly in the stomach and/or colorectum. Our recent study indicated that JRTs with GI neoplastic polyps harbor an identical germline variant in the APC gene, c.[462_463delinsTT], in a heterozygous state. Unlike sporadic cases, dogs afflicted with hereditary GI polyposis can be expected to have a prolonged survival time, as hereditary tumors are noninvasive. Since the discovery of this disease, the number of newly diagnosed cases in Japan has increased, allowing us to update the clinical and pathological features and provide a large number of diagnostic images. The present clinical case series study employing various diagnostic imaging techniques revealed that some of the cases harbored tumors in the small intestine in addition to the stomach and colorectum. Moreover, although rare, hereditary GI cancers can progress to the advanced stage and develop systemic metastasis, similar to sporadic GI tumors. These findings indicate that there is a wider range of variation in disease severity than was initially recognized. Our results can contribute to the accurate diagnosis of hereditary GI polyposis in clinical practice, pathological examinations, and future research.