Parasites

• Parasites and protozoans are one of the most common causes of upset stomachs in cats. They are easily ruled out by having a veterinarian run a fecal test on a fresh stool sample.
  
  

Sudden Diet Changes

• Cats that suddenly change diets may display vomiting and diarrhea. Sudden diet changes should be done gradually over the course of at least a week.
  
  

Dietary Indiscretion

• A cat that gets into the trash or eats too much of something may develop vomiting and diarrhea. This is usually solved after the culprit food is removed.
  
  

Intestinal Obstruction

• Cats at times may ingest foreign objects that may lodge in the intestinal tract and cause a blockage. Affected cats may have persistent vomiting, abdominal pain, difficulty passing stools or diarrhea.
  
  

Toxins

• Cats may be be exposed to chemicals or poisonous plants. Affected cats may exhibit a variety of symptoms, ranging from vomiting and diarrhea to drooling, seizures, distress, coma and even death.
  
  

Metabolic Disorders

• In some cases, vomiting and diarrhea may ultimately be due to metabolic disorders. These encompass various conditions often affecting the kidneys, urinary tract, liver, immune system and endocrine system.
  
  

Solutions

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  Cats affected by mild cases of vomiting and diarrhea should be fasted 12 hours and given a bland diet. Because of the risks of dehydration, it is always best to have a veterinarian properly diagnose, treat and assess a cat that is exhibiting symptoms of gastrointestinal problems.