• Kittens get diarrhea for many reasons; in older cats, it might indicate serious illness.Kittens in the Sun image by Honda Rode from Fotolia.com
  
  Diarrhea in any cat is not a good thing; however, in a cat reaching its senior years, it may be a sign of serious disease. Felines begin to experience age-related health problems just like humans. Changes in diet, regular veterinary exams, vitamins and supplements, grooming assistance and comfortable environments can all ease the feline into senior years. If an old cat has an unusual bout of diarrhea, however, there may be an age-related underlying cause.
  
  

Kidney Disease/Failure

• Bad breath and diarrhea might indicate kidney disease.roar image by Justin Hall from Fotolia.com
  
  Kidney disease is a common ailment of senior cats because the kidneys simply begin to deteriorate over time. In addition to diarrhea, a feline suffering from kidney disease will begin to drink water and urinate more frequently. This is because the kidneys are no longer filtering toxins out of the blood effectively and the cat must produce more urine to remove the waste. Vomiting, rancid breath and mouth ulcers are also symptoms of kidney disease. Once diagnosed, special diet, medication and IV fluids may help hold the disease at bay; however, kidney disease is chronic and there is a good chance the feline will eventually die from the disease, according to VetInfo.
  
  

Inflammatory Bowel Disease

• Inflammatory bowel disease can be painful.Sleeping cat image by Xarthias from Fotolia.com
  
  The most logical underlying condition of diarrhea in old cats is inflammatory bowel disease. This frustrating and painful condition for both the feline and its owner may require abdominal surgery to pinpoint its exact cause. Inflammatory bowel disease occurs when the cells in the lining of the older cat's digestive tract become inflamed. The causes of the inflammation could be something as simple as a parasitic invasion or something as serious as the feline leukemia or feline immunodeficiency viruses, according to Cornell University's College of Veterinary Medicine. Much like kidney disease, inflammatory bowel disease cannot be cured. It can, however, be controlled effectively with the proper diet and medications such as corticosteroids and antibiotics, when necessary.
  
  

Liver Disease

• Yellowing of a jaundiced cat's skin is most noticeable on its ears.ear image by Alexandr Potapov from Fotolia.com
  
  Unless the senior cat becomes jaundiced--with yellowing of the skin, gums and eye whites--veterinarians have a hard time diagnosing liver disease based on diarrhea and its other symptoms alone, because the symptoms of liver disease can point to several medical conditions. Consequently, when the older cat is taken to the vet to determine the underlying cause of its diarrhea, it will be subjected to numerous tests. These tests include a complete physical exam, blood chemistry panel, blood coagulation tests, bile acid tests, urinalysis and imaging to view the physiological condition of the liver. If none of these tests prove conclusive, the older feline may have to undergo a liver biopsy to determine the presence and extent of liver disease. Treatment of liver disease is much like the treatment for the other conditions that cause diarrhea in older cats. Dietary changes, medications, hydration therapy and vitamins all aid in keeping the senior cat comfortable until it succumbs to the disease, according to Doctors Foster and Smith of Pet Education.com.