The 9 Most Common Virus Diseases Afflicting Cats

There are 9 common virus diseases that can afflict a cat. Each of these infectious diseases have unique clinical characteristics and structural characteristics. Vaccines are available for many of these virus diseases. Following the vaccination advice of your vet will help protect your cat and extend her life.

Common Structural Characteristics

Each virus differs slightly in its structure but a basic structure exists in all viruses. Each virus contains either DNA or RNA which is surrounded by a capsid which is a protective shell made of protein. A virus contains genetic material in one of four forms. It can have a single strand of DNA or a double strand of DNA and the same two options in RNA.

Clinical Characteristics

Each virus can manifest in a variety of ways. The most common feline virus diseases either suppress the immune system or cause inflammation in an organ or specific area of the body. In the immune suppressing viruses, the most common symptoms include lethargy, loss of appetite, fever and/or frequent infections. In the viruses that cause inflammation, symptoms relate to the area of the body that is infected.

Most infectious diseases can be diagnosed via a simple blood test. The vaccinations might not completely protect your cat but greatly reduce the likelihood of affliction. Most of these virus diseases are highly contagious amongst cats but cannot be spread from a cat to another animal species or human.


This virus usually causes feline leukemia. It can also cause some forms of cancer and anemia. FELV is contagious amongst cats but cannot be spread to humans or other animals such as a dog. It spreads through contact with infected tears, saliva, or urine via shared food dishes, litter boxes, bite wounds. A cat can become infected by grooming an infected cat, and a kitten can become infected through infected mother's milk.


This is the feline immunodeficiency virus and is sometimes referred to as feline AIDS. FIV launches a widespread attack on the cat's immune system. Illness and death come from any number of secondary infections and illnesses that the body cannot fight.

Feline Calicivirus, Feline Herpesvirus (FVR) and Chlamydophila

These are the most common viruses that affect the upper respiratory systems. Inflammation, discharge, ulcers, and swelling occurs in the eyes, nose and mouth.

Bordetella and Mycoplasma

These viruses attack the lower airways, i.e. the trachea and lungs. The cat may have trouble breathing or may have a raspy sound to his meow.

Feline Infectious Peritonitis (FIP)

This is one of the slow acting feline virus diseases. It can cause inflammation in several different organs. It can result in serious illness and death.


This is the most common virus that causes problems in the cat's digestive tract. Diarrhea and vomiting are telltale clinical signs.