Many Things Cause Dog Diarrhea

Q. My 45-pound, 8-year-old mixed-breed dog has days when he won’t eat and ignores treats. He has diarrhea when he goes out. During these times he also eats grass. Do these symptoms suggest anything?

A. Your dog’s occasional loss of appetite – combined with diarrhea and grass-eating – suggests a number of possibilities. Something seems to inflaming his stomach and intestines, possibly making him nauseated and causing the diarrhea.
 
Some dogs are very sensitive to certain foods and can develop allergies. Although it is not recommended to make frequent diet changes, you might try changing your dog’s diet to something with a completely different set of ingredients such as lamb and rice.
 
Another basic strategy is to submit a stool sample to your veterinarian for analysis. Your veterinarian will also want to examine your dog. Although parasites are more common in younger dogs, middle-aged and older dogs can acquire infections of micro-organisms such as giardia or clostridium, both of which can cause loss of appetite and diarrhea. Both infections are treatable with appropriate antibiotics.
 
Another possibility is a generalized inflammation of the bowel called inflammatory bowel disease (IBD) which is the equivalent of Crohn’s disease in humans. The immune system tends to attack its own intestinal lining, causing it to thicken and not absorb nutrients correctly. The result is diarrhea and occasionally loss of appetite.

During an endoscopy procedure a scope is placed through your anesthetized dog’s mouth and passed to the stomach and intestines. A small sample of intestine is taken and submitted for biopsy.
 
To avoid the expense of endoscopy and risk of anesthesia, some veterinarians will start a trial treatment of prednisone to treat the IBD. If the patient responds, then the diagnosis is confirmed, and treatment continues. Prednisone helps suppress the immune system which is causing the problem with the intestinal lining.
 
Waxing and waning diarrhea, and loss of appetite, can also be caused by Addison’s disease. This is a hormonal imbalance of the adrenal gland and must be diagnosed with some blood tests.
 
The list goes on. If your dog seems to be only having occasional issues, you might just try a simple diet change to see if it helps. Occasionally adding a small amount of plain yogurt to the food once a day can help settle the stomach and intestines. If the symptoms worsen or are not improving, see your veterinarian to get your dog diagnosed and treated correctly.