Initially the symptoms of feline infectious peritonitis are not very obvious. Once the symptoms begin to appear, they may become worse and ultimately result in death. The affected cat may show signs like weight loss, lack of appetite, dull coat, and sneezing, watery eyes. Sometimes, there may be intestinal discomfort and diarrhea.

 There are two forms of feline infectious peritonitis- the dry form and the wet form. The dry or non-effusive form of feline infectious peritonitis is characterized by weight loss, lethargy, depression, anemia and persistent fever. Some cats my develop granulomas or paralysis. They may be loss of balance, tremors, convulsions and urinary incontinence due to disturbances in the nervous system. This form of the disease is defined by inflammation in organs like the liver and kidneys. The effusive or wet form of the disease is characterized by fluid accumulation in the abdomen and chest.

 This form of the disease is also associated with signs like weight loss, fever and lethargy. The effusive form of the disease progresses more rapidly. The cat may develop a pot bellied appearance due to accumulation of fluid in the abdomen. As more and more fluid accumulates in the chest and abdominal cavities, it becomes more difficult for the cat to breathe.