Irritable Bowel Disease

• Among the symptoms of irritable bowel disease (IBD) are diarrhea, vomiting and weight loss. Sometimes all it takes to relieve the symptoms is a change in diet. Other therapies include the use of medication, usually Prednisone.
  
  

Hyperthyroidism

• Some untreated hyperthyroid cats have diarrhea, along with weight loss despite a ravenous appetite. Thyroid medication or a radioactive iodine injection are the treatments for feline hyperthyroidism.
  
  

Pancreatitis

• Along with diarrhea and weight loss, symptoms of pancreatitis include lethargy, dehydration and loss of appetite. Treatment often includes subcutaneous fluids, pain medication and nutritional support.
  
  

Pancreatic Insufficiency

• Cats with pancreatic insufficiency usually produce a high volume of loose or semiformed stools. The most common treatment for pancreatic insufficiency is adding pancreatic enzymes to the cat's food.
  
  

Intestinal Lymphoma

• The symptoms of intestinal lymphoma include vomiting and diarrhea, weight loss, and a rough hair coat. Chemotherapy is one of the treatments used for lymphoma in cats.
  
  

Intestinal Parasites

• Such intestinal parasites as roundworms, hookworms, coccidia and giardia can cause diarrhea and weight loss. All are treated with medication.