Inflammatory Bowel Disease is relatively common in older cats, but can be seen in younger cats, as well. It is characterized by frequent vomiting and/or diarrhea, although frequent vomiting seems to be more common. Vomiting cats can also have intestinal lymphoma, and IBD, along with intestinal lymphoma, account for around 90% of cases with chronic vomiting and/or diarrhea as the main presenting symptom. Many cat caretakers think their cat is just “a vomiter” and are not terribly concerned about it. Diarrhea, on the other hand, seems to bother people more than the vomiting, and the cat is more likely to be seen by a veterinarian when chronic diarrhea is present. Stress can also play a role in chronic diarrhea and causes a syndrome called IBS or Irritable Bowel Syndrome, which usually results in colitis or inflammation of the colon. IBD is described as a chronic inflammatory condition of the stomach and/or small intestine and/or large intestine. Because IBD can affect different parts of the gastrointestinal tract, the location determines what the disease is called. If it affects the stomach it, is called gastritis; if it affects the small intestines, it is called enteritis; and if it affects the colon, it is called colitis. If the upper part of the gastrointestinal tract is involved, vomiting will be the most prevalent symptom, while if the lower part of the intestines are affected, diarrhea will be seen rather than vomiting. In IBD, inflammatory cells infiltrate the walls of the intestines and interfere with normal digestion. The actual cause of IBD in cats is still unknown, but thought to be related to the immune system (food allergy) and its interaction with the bacteria in the intestine. Genetics may also be involved. Diagnosis can be quite involved and may require abdominal ultrasound and/or biopsies of the gastrointestinal system. Treatment can be as simple as a diet change to a prescription hypoallergenic diet, but usually involves other treatment modalities such as metronidazole and/or corticosteroids. 

https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/inflammatory-bowel-disease

Intestinal Lymphoma is a relatively common disease of older cats, but can be seen in younger cats as well. There are other forms of lymphoma that can afflict other organs of the body, but this synopsis will only be about the intestinal form. As mentioned in the discussion about IBD, this disease accounts for about 45% of vomiting cats or those with chronic diarrhea. As with IBD, any part of the intestine can be affected and the more common symptoms are associated with the area involved: vomiting with upper intestinal disease and diarrhea with lower intestinal disease. When both locations have the disease, vomiting and diarrhea are seen. Weight loss is often seen and the appetite may be affected as well. In some cases, a mass will be palpable in the abdomen on physical exam. However, in many instances, nothing is felt although there may be an idea that the intestines feel “thickened.” Blood tests are, in many cases, normal as are radiographs. An ultrasound of the abdomen (recommended in all cases suspected) may show thickened intestines with a distinct layering effect and/or intestinal masses. Adjacent lymph nodes may also be enlarged. A very good ultrasound doctor (or technician) should be able to differentiate the difference between IBD and intestinal lymphoma on ultrasound as each disease shows specific changes to the wall of the intestine affected. Unfortunately, both diseases can coexist together. Biopsies of the intestine are usually required for confirmation but, unless full thickness (a complete section of the intestinal wall) biopsies are done, the pathologist may not be able to be sure. Using a special flexible scope to obtain the samples, although much less invasive than actual surgery, may not be the best approach because full thickness samples cannot be obtained that way. However, this type of biopsy works well for diagnosing IBD because with that disease, the interior wall of the intestine is affected. Once the biopsy confirms that intestinal lymphoma is present, the type of cell involved further complicates the diagnosis. Small cell lymphoma is less malignant and responds to treatment much better than the other type, large cell lymphoma, which carries a much more ominous prognosis and often does not respond to chemotherapy. Go to the following articles for more information:

https://www.vetfolio.com/learn/article/gastrointestinal-lymphoma-in-cats

https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/lymphoma

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