Genetic basis - Gastrointestinal (GI) polyposis in dogs, particularly studied in Jack Russell Terriers (JRTs), is a hereditary condition caused by a germline mutation in the adenomatous polyposis coli (APC) gene. This autosomal dominant mutation leads to the development of solitary and multiple tumors, primarily in the stomach and colorectum, though some cases involve the small intestine as well. The specific mutation identified in affected JRTs is a heterozygous c.[462_463delinsTT] variant in the APC gene
Pathophysiology - The APC gene mutation disrupts tumor suppression pathways, leading to the development of adenomatous and adenocarcinomatous polyps in the gastrointestinal tract. Unlike sporadic GI tumors, hereditary GI polyps in affected dogs tend to be less invasive, often confined to the mucosa or submucosa, but malignant transformation and systemic metastasis have been reported in severe cases. The disease's manifestations can vary widely in severity and location throughout the GI tract
Complications - Vomiting, sometimes with blood, especially with gastric tumors. Increased frequency of defecation, diarrhea, and bloody stools in cases with colorectal involvement. Rectal prolapse in some cases due to colorectal polyps. Anemia and low plasma albumin levels, likely from bleeding and malabsorption. Potential progression to gastric or colorectal cancer with risk of metastasis in advanced disease stages
Why This Matters to Breeders and Vets - GI polyposis significantly impacts affected dogs' health and quality of life, with potential progression to cancer. Awareness among breeders and veterinarians facilitates early genetic testing, diagnosis, and appropriate management. For breeders, responsible breeding based on genetic testing can reduce incidence and improve breed health. For veterinarians, recognizing clinical signs and using diagnostic imaging alongside genetic tests enhances patient care and prognosis.