Dear Doctor - February 2013
Letter to Tufts Veterinarians
Senior cat with digestive issues
Q My cat Gizmo is 15 years old and has been having digestive problems and persistent diarrhea. He has lost five pounds in the past few months and I cannot seem to control his loose bowels. I have tried two different enzymes and I have been giving him probiotics that I bought from PetSmart, made with Alaskan salmon oil. So far, his problem still persists.
He has been tested for thyroid problems and possible blood conditions and received X-rays, but my veterinarian did not find anything. I hate to see Gizmo dwindle away like this. He never leaves the room where the litter box is and he is lethargic. He is always hungry, but yet he cannot retain any nourishment. I feel that if I cannot help him soon he will not last much longer.
Dear Louis: I am sorry to hear Gizmo is feeling down. Fortunately, he has the rare combination of weight loss despite excessive appetite. There are few diseases that cause that combination of signs: diabetes, hyperthyroidism, lack of digestive enzymes and disease of the small intestine. Treatment is available for each of these conditions.
I will presume that diabetes and hyperthyroidism have been excluded because of the normal blood tests you reported. Lack of digestive enzymes can be tested with a blood test called trypsin-like immunoreactivity (TLI, for short). This condition (lack of digestive enzymes) is extremely rare and I will therefore discuss the final condition (disease of the small intestine) as the most likely culprit.
All food must be absorbed in the small intestine. Without absorption food merely passes through the body causing diarrhea and weight loss. Several different small intestinal diseases are known — with food intolerance, inflammation and cancer being the most common.
An accurate diagnosis would often include an X-ray of the lungs, ultrasound of the intestine and biopsy of the small intestine. Biopsies may be obtained through surgical or endoscopic methods. Results often guide the most effective therapy. One particular condition you should be aware of is small cell lymphoma of the small intestinal tract. This form of cancer — quite common in elderly cats — is actually a very benign cancer with a good prognosis. With appropriate therapy, most cats live one to two years after the diagnosis is made.
I would encourage you to discuss further diagnostics with your veterinarian. You may be offered consultation with a veterinary internal medicine specialist who has advanced training in the diagnosis and treatment of intestinal diseases. If you cannot afford extensive diagnostics, I would consider the submission of a blood serum trypsin like immunoreactivity (TLI) and if normal, treatment for small cell lymphoma of the intestine.
Michael Stone, DVM, ACVIM
Clinical Assistant Professor
Cummings School of Veterinary Medicine at Tufts University