Cats Have Way More GI Tumors Than Dogs? What a National Cancer Database Just Revealed

When GI Signs Mean Something Bigger

Gastrointestinal disease is one of the most common reasons pets present to veterinary clinics. Vomiting, diarrhea, weight loss, and anemia are everyday complaints, yet behind these familiar signs can be some of the most challenging cancers we diagnose. A new comparative epidemiological study from Portugal sheds light on how tumors of the digestive system differ between dogs and cats, and the results reinforce something clinicians already sense in practice. These species are not playing the same oncologic game.

Using data from the Vet-OncoNet database, researchers evaluated 1,213 confirmed digestive tract tumors in dogs and cats across Portugal. The study population was almost evenly split between species, with a slight male predominance overall. By examining tumor location, histologic type, breed, and geographic distribution, the authors were able to identify meaningful species-specific patterns that have real clinical relevance.

Across both species, the small intestine emerged as the most frequently affected organ, followed by the liver and intrahepatic bile ducts. When dogs were evaluated separately, tumors most often involved the liver and bile ducts, with rectal and small intestinal tumors also common. In cats, however, the picture was strikingly different. Nearly forty percent of feline digestive tumors originated in the small intestine, far outpacing any other location.

For clinicians, this finding reinforces the importance of taking chronic feline gastrointestinal signs seriously. In cats, vague signs like intermittent vomiting or weight loss are far more likely to represent neoplasia than they are in dogs.

Lymphoma Dominates, Especially in Cats

Lymphoma was the most common digestive tumor in both species, accounting for just over forty percent of cases. Adenocarcinoma was the second most frequent diagnosis. The real headline, however, was the dramatic difference in incidence between species. Cats had a digestive tumor incidence rate three and a half times higher than dogs. Male cats were particularly overrepresented, with a significantly higher incidence than females. Even more striking, cats had a sixteen-fold higher risk of gastrointestinal lymphoma compared to dogs and double the risk of adenocarcinoma. These data help explain why feline GI workups so often end with an oncology consult and why intestinal biopsies in cats frequently deliver life-altering diagnoses.

Certain dog breeds, including Labrador Retrievers, German Shepherds, and French Bulldogs, appeared frequently in the dataset, with some breeds such as West Highland White Terriers and Golden Retrievers showing higher incidence rates. In cats, most cases involved common mixed-breed and European-type cats, reflecting both population demographics and disease burden. Geographic analysis revealed clustering of digestive tumors in densely urbanized areas, particularly around Porto and Lisbon. While this does not establish causation, it raises important questions about environmental exposures, lifestyle factors, and access to advanced diagnostics that may influence cancer detection rates.

Why This Study Matters in the Exam Room

The findings from this study highlight that digestive tumors are not only common but biologically distinct between dogs and cats. Cats, especially males, carry a much higher risk of intestinal neoplasia, with lymphoma leading the charge. These differences underscore the need for species-specific diagnostic thresholds and reinforce the value of early imaging, biopsy, and referral in feline GI cases. For veterinary professionals, this research offers strong epidemiological support for instincts many clinicians already have. When a cat presents with chronic gastrointestinal signs, cancer should always be high on the differential list.

To read the original article: Click Here