Respiratory infections of cats are caused by numerous organisms. The most common are several different viruses and microbes that infect the tissue of the nasal cavity, respiratory passages and lungs, eyes and sometimes the mouth. These respiratory infections can range from mild to very severe illnesses. All are contagious from cat to cat, some more extremely so than others. Respiratory infections are often spread by licking and grooming between cats and sharing food and water dishes. Some are also spread by sneezing and coughing although this may occur only over short distances. Nasal discharge, sneezing, or reverse sneezing in cats are often signs of diseases that may require veterinary care.
The most common signs of a feline respiratory disease include sneezing, fever, watery to sticky puslike discharge from the nose and eyes, lack of appetite, and lethargy. Sometimes drooling is seen, and in these instances ulcers can often be found on the tongue or hard palate. Some very mild infections are marked only by evidence of a mild eye irritation (conjunctivitis) accompanied by a small amount of watery eye discharge and no other signs. In severe cases the eyes can be swollen and crusted shut from discharge, the nasal passages clogged, the nose ulcerated, and the cat most uncooperative with any efforts to give aid.
Respiratory infection in which the signs are mild (small amounts of watery eye and/or nose discharge and a few sneezes unaccompanied by fever) usually do not require veterinary care if the cat is eating normally and does not seem unduly depressed. Cases accompanied by any of the following signs should alert you to have your cat examined by a vet: persistent fever, lack of appetite, marked listlessness, dehydration, puslike eye or nose discharges, or cough (a sign that the infection may include the lower air passages or the pneumonia may be present). Prompt and intensive treatment is necessary to avoid undesirable aftereffects or respiratory infections. Whether a respiratory infection is mild, moderate, or severe depends upon many factors, such as age, general health, the acquired resistance from previous exposure or vaccination, and the strain of the infective organism.
Agents Causing Feline Respiratory Infections
Feline Viral Rhinotracheitis (FVR, "rhino") is caused by herpesvirus type 1. Signs include sneezing, coughing, eye and nose discharge, fever, drooling, lack of appetite, and termination of pregnancy (miscarriages). Usually severe infection of longer than 1 week's duration which can be fatal. Infected newborn usually weaken and die. Virus remains infective 1 to 2 days in the environment. Most recovered cats remain carriers.
Chlamydia psittaci infection (formerly feline pneumonitis) is caused by Chlamydia psittaci variety felis. In young and adult cats it causes conjunctivitis, squinting, and watery eye discharge. In newborn it causes fatal pneumonia. Usually mild infection is acquired by intimate exposure. Signs may last 4 to 6 weeks. The disease responds to antibiotics and may occasionally cause human conjunctivitis. Recovered cats may become carriers.
Feline calicivurus (FCV), formerly feline influenza, is caused by calicivurus. Most often transient fever and lameness lass up to 4 days. Tongue and mouth ulcers are seen often followed by drooling and eye and nose discharge. Symptoms vary and become most severe in combination with other infections. There are more than 15 different virus strains and vaccines may not provide full protection against all strains. The virus remains infective up to 10 days in the environment. Recovered cats may become carriers and may have severe chronic mouth disease.