Small Cell GI Lymphoma: A Hidden Cancer Behind Feline Digestive Issues
It’s not unusual for cats to have the occasional upset stomach, but when issues persist, something more serious could be going on.
One possible hidden cause is small cell gastrointestinal (GI) lymphoma, a type of cancer that develops in the digestive tract and interferes with how the body absorbs nutrients. Because its signs resemble many common stomach issues, it can be hard to recognize.
Dr. Regina Hayburn, a clinical assistant professor at the Texas A&M College of Veterinary Medicine & Biomedical Sciences, shares what cat owners should know about small cell GI lymphoma, from recognizing warning signs to understanding how it’s diagnosed and treated.
Understanding The Disease & Its Signs
Lymphoma is a cancer of lymphocytes — immune cells that help the body fight infection — that causes both an overproduction of these cells and hinders their ability to function as they should. Because the GI tract contains a large number of these cells, it’s a common place for lymphoma to develop in cats.
“Small cell GI lymphoma is the most common cancer of a cat’s digestive system and a highly prevalent feline cancer overall,” Hayburn said. “It can form anywhere along the digestive tract, including the stomach, small intestine, or colon.”
This cancer is thought to be a spectrum of disease with inflammatory bowel disease, which is characterized by chronic inflammation in the GI tract that leads to abnormalities in the intestinal walls. This can alter how food and water move through the system and are absorbed.
Unlike large cell GI lymphoma — a much rarer form that causes sudden, severe illness — small cell GI lymphoma develops slowly, with signs often progressing over months to years.
“Because of the impaired motility and absorption, chronic vomiting and diarrhea are common, along with weight loss and decreased appetite, although some cats maintain a normal or even increased appetite in early stages,” Hayburn said. “As the disease progresses, cats often stop eating, vomit more frequently, and become increasingly lethargic and generally unwell due to chronic illness and weight loss.”
Getting A Diagnosis
Because symptoms resemble other digestive issues, the condition can be difficult to identify without proper testing. Bloodwork to evaluate overall health is an important first step.
While an abdominal ultrasound can show thickened GI wall layers or changes to the intestinal walls, it can’t confirm cancer. The only way to definitively diagnose GI lymphoma is through a tissue biopsy — removing a tissue sample for microscopic examination.
“Tissue biopsy can be done by endoscopy or surgery,” Hayburn said. “Endoscopic biopsies are minimally invasive but obtain really small pieces of tissue. Surgical biopsies can collect tissue samples from different parts of the intestine and include full intestinal thickness samples, but the con of this is that it’s an open-abdomen surgery.”
Once tissue is collected, veterinarians use additional tests to distinguish GI lymphoma from conditions like irritable bowel disease, which appears similar under ultrasound but requires different treatment.
Treatment Options
Small cell GI lymphoma is treatable but often requires long-term chemotherapy.
“The most common treatments involve oral chemotherapy (Chlorambucil) given at home and oral steroids (prednisolone). These medications can be given long-term and help control this disease for years,” Hayburn said. “This is generally well tolerated, but oral medications can be challenging for some cats.”
Because of this, veterinarians at Texas A&M are exploring new treatment options.
“We have a clinical trial generously funded by EveryCat Health looking at using radiation therapy in relapse cases, or those that did not see improvement with chemotherapy,” Hayburn said. “This would make treatment easier for cats who are difficult to orally medicate or who don’t like frequent veterinary visits.”
When undergoing chemotherapy treatment, success is measured by how the cat feels rather than imaging results.
“Abdominal ultrasounds might still show visible signs of the cancer even when the cat is feeling much better,” Hayburn said. “As long as the cat’s physical symptoms are managed — where the cat is eating well, gaining weight, and having minimal to no vomiting and diarrhea — the treatment plan is likely effective and doesn’t need to be changed.”
With early detection and attentive care, many cats go on to live happy, comfortable lives for years after diagnosis.
Pet Talk is a service of the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University. Stories can be viewed on the web at vetmed.tamu.edu/news/pet-talk. Suggestions for future topics may be directed to vmbs-editor@tamu.edu.
