What are the symptoms of feline infectious peritonitis?

The symptoms of feline infectious peritonitis (FIP) are quite diverse, mainly divided into the effusive form (wet form) and the non – effusive form (dry form). The specific manifestations are as follows:

I. Effusive Form (Wet Form)

1. Abdominal Effusion
   • This is one of the most common symptoms of effusive FIP. The abdomen of the affected cat will gradually enlarge, and a fluctuation can be felt by touch, just like a water – filled balloon. This is because the virus infection causes inflammation, leading to an increase in the permeability of blood vessels in the abdominal cavity, and plasma proteins and fluids exude into the abdominal cavity to form effusion.
   • The abdominal effusion will make the cat feel uncomfortable and result in a loss of appetite. In severe cases, the cat may have difficulty breathing due to abdominal pressure, manifested as rapid breathing and open – mouthed breathing.
2. Pleural Effusion
   • Some affected cats will have pleural effusion. This will significantly affect the cat’s respiratory function, causing symptoms such as coughing, shallow and rapid breathing, and wheezing. If listening to the cat’s chest, wet rales can be heard in the lungs because the effusion in the chest cavity affects the normal expansion of the lungs and gas exchange.

II. Non – Effusive Form (Dry Form)

1. Ocular Symptoms
   • Many cats with non – effusive FIP will have ocular lesions. Uveitis is common. In this case, the inside of the cat’s eye will be inflamed, and the eye may appear red and cloudy, and the pupil’s response to light becomes sluggish. In severe cases, it can lead to blindness, and the affected cat will show inconvenience in movement, often bumping into objects.
   • Hyphema or hypopyon may also occur, which will further damage the structure and function of the eye.
2. Nervous System Symptoms
   • The cat may have weakness in the hind legs and unsteady walking, like being drunk. This is because the virus infection affects the normal function of the nervous system, resulting in nerve conduction disorders.
   • Some affected cats will also have severe symptoms such as convulsions and epileptic seizures. These symptoms are often intermittent, but each episode will cause significant harm to the cat’s body, causing the cat’s physical condition to gradually deteriorate.
3. Organ Enlargement
   • The internal organs such as the liver, spleen, and kidneys of the affected cat may enlarge. For example, when the liver enlarges, a hard mass may be felt in the upper right abdomen of the cat from the outside. The enlargement of these organs is due to the virus replicating inside the organs, triggering an inflammatory response, leading to cell proliferation and tissue edema. The enlarged organs will affect their own functions, thereby causing systemic health problems in the cat, such as jaundice (when liver function is affected) and digestive disorders.

The symptoms of feline infectious peritonitis are complex and somewhat concealed. If any of the above – mentioned suspicious symptoms are found in a cat, it should be taken to a veterinarian for examination in a timely manner for early diagnosis and treatment.