Lymphoma is one of the most common cancers in cats and most frequently affects the gastrointestinal (GI) tract. GI lymphoma can be classified as low-grade alimentary lymphoma (LGAL) or high-grade alimentary lymphoma (HGAL), which differ in their biological behavior, treatment, and prognosis.  

LGAL grows slowly with median survival times of 1.5 - 2.5 years. However, diagnosis can be challenging because clinical signs often resemble inflammatory bowel disease (IBD), meaning invasive intestinal biopsies are often required for a definitive diagnosis. A non-invasive diagnostic test that could distinguish LGAL from IBD at presentation would allow earlier diagnosis and timely treatment.

In contrast, HGAL is an aggressive disease characterized by variable responses to chemotherapy and variable survival times. Current monitoring relies on ultrasound and clinical assessment, which lack sensitivity for detecting residual disease and early relapse. Improved biomarkers are needed to provide objective measures of disease burden and treatment response.

This study will investigate circulating cell-free DNA (cfDNA), fragmented DNA released into the bloodstream during normal cell turnover and disease processes, as a minimally invasive biomarker for feline GI lymphoma. We will evaluate the diagnostic utility of plasma cfDNA in cats at initial presentation, primarily to distinguish LGAL from IBD. We will also assess serial cfDNA measurements for monitoring disease burden, treatment response, and progression in cats with LGAL and HGAL. The findings may support the development of blood-based tools for the diagnosis and clinical management of feline lymphoma.