Some people think it’s funny, but…well you know.
Bob Baker, DVM
If you Google “Fecal Score” you see some great albeit somewhat graphic representations of differing dog and cat stool consistencies. Suffice to say we all likely have a pretty good idea of what diarrhea is.
Occasional diarrhea is fairly common in the dog, less common in cats. There are many causes of diarrhea: Bacterial infections, parasitic infections, liver and pancreas problems, primary small and large intestinal disease, dietary intolerance, dietary misadventures, and cancer can all be potential sources for diarrhea. Occasional diarrhea that resolves within 24 hours, that is not associated with blood in the stool, vomiting, loss of appetite, or lethargy does not generally require a trip to the veterinarian. Most over the counter medications used for diarrhea in people are not a good idea to give to our pets. Pepto Bismol, Kaopectate, and Immodium are not considered useful, and some ingredients can actually be toxic to pets. The best thing for the occasional diarrhea in an otherwise healthy dog is to withhold food initially for 12-24 hours, (never water) and the offer a bland diet (Hill’s I/D) or a homemade bland diet (boneless skinless chicken breast and white rice). In the cat, occasional diarrhea is less common and if your cat has diarrhea more than once they probably should be looked at.
Diarrhea that does not resolve in 24-48 hours or is associated with vomiting, bloods in the stool, or signs of illness should be addressed by your veterinarian. It is helpful to bring a fresh stool sample to the office if available. Tupperware or even a clean baggie will suffice if the sample can be obtained. The history of the diarrhea can be helpful in making a diagnosis. Recent changes in diet, whether the diarrhea has any blood or mucous in it, whether there is urgency associated with defecation, and also the volume and frequency will help your veterinarian determine the best course of proceeding with diagnosis and treatment.
Testing for acute onset diarrhea depends on how sick the patient is. If the pet is otherwise healthy, a fecal smear or a parasite test may be all that’s required. If the patient is notably sick, then other tests including routine blood testing may be indicated.
Chronic diarrhea is a much more involved workup that can involve more specific blood testing for pancreas function, and vitamin levels in the blood. Deeper investigation into the stool with cultures and PCR testing for infections may be indicated. Imaging tests like ultrasound can be helpful in some cases. Definitive testing for case that cannot be diagnosed by non-invasive testing would lead us to the next level which is getting a tissue biopsy of the gut. There are three ways to get tissue biopsies. Endoscopy is a procedure where a flexible tube with a camera on the end is passed into the anesthetized patient from form the mouth or the rectum. From there, the veterinarian can inspect the inside of the gut, and using special tools collect small biopsy samples from the lining. This is the least invasive way to get a biopsy, but is limited by the small sample size and the inability to inspect the entire intestinal tract. An abdominal exploratory will allow access to all levels of the gastrointestinal tract and allow for full thickness biopsy samples which are preferred by pathologists. The downside is that the procedure is quite invasive and a large incision is required to gain access to the abdomen. An in between method, called laparoscopic surgery is performed using smaller incisions with camera and surgical instruments inserted into the abdomen through small holes. In laparoscopic assisted procedures, you can still get the full thickness biopsy samples without the large incision.
Most acute onset diarrheas will resolve on their own, or with minimal intervention. Diarrhea that is chronic in nature needs a diagnosis to be managed properly. Any animal that is noticeably sick or ill should evaluated as soon as possible.