What causes a feline upper respiratory infection?
Feline upper respiratory infection (URI) is one term for a respiratory infection caused by one or more viral or bacterial agents. Synonyms for this condition include feline infectious respiratory disease and feline upper respiratory disease complex (URD). The infection may be caused by one or more viral and bacterial agents that are capable of causing disease in cats. The most common viruses that cause upper respiratory infections in cats are Feline Herpesvirus Type-1 (also known as feline viral rhinotracheitis or FVR) and Feline Calicivirus (FCV), while the most common bacteria that cause upper respiratory infections in cats are Bordetella bronchiseptica (B. bronchiseptica) and Chlamydophila felis(C. felis). More information about the most common infectious agents that cause an upper respiratory infection in cats can be found in separate handouts in this series of client education materials. Other, less common, agents that may be involved in an upper respiratory infection in cats include mycoplasma or feline reovirus.
What are the symptoms of an upper respiratory infection?
"The typical upper respiratory infection involves the nose and throat..."
The typical upper respiratory infection involves the nose and throat, causing symptoms such as sneezing, nasal congestion, conjunctivitis (inflammation of the membranes lining the eyelids), and discharges from the nose or eyes. The discharges may be clear or may become purulent (containing pus). With FVR and FCV, the cat may develop ulcers in the mouth. Other, less specific symptoms of an upper respiratory infection include anorexia, lethargy, fever, enlarged lymph nodes and blepharospasm (squinting). In severe cases, the cat may have difficulty breathing.
How does a cat get an upper respiratory infection?
The main viruses and bacteria that cause URI in cats are highly contagious. An infected cat will shed contagious particles in saliva or secretions from the nose or eyes. Susceptible cats can get an infection by direct contact with another infected cat or by environmental exposure to objects that have been contaminated with infectious secretions. In the majority of cases, the cat gets an infection by direct contact since the viruses and bacteria can only survive for a short period of time in the environment, and they are readily destroyed by proper disinfection procedures.
Several of these diseases can cause a carrier state in cats that have apparently recovered from an infection, and female cats that are carriers can pass the infection on to their newborn kittens.
How long does a typical upper respiratory infection last?
Once a cat is exposed to an infectious agent, it will go through an incubation period of 2-10 days before developing symptoms. If the infection is uncomplicated, it will typically last for 7-21 days, depending on the particular disease agent. During this entire time, the cat will potentially be infectious to other cats.
With FVR, all cats become chronic carriers, meaning that they will have the disease essentially for life. In some cats that are carrying FVR, stress may cause the virus to become reactivated. With calicivirus, about half of the cats that are infected will become carriers of disease. In some of these cats the carrier state may only last for a few months, but in a small percentage of cats the carrier state may persist for life. These persistent carriers are usually free of symptoms but serve as a constant source of virus to susceptible cats.
How is an upper respiratory infection diagnosed?
In most cases, diagnosis of an upper respiratory infection is based on the characteristic clinical signs. Specific identification of the causative agent is not always necessary, but will be recommended for breeding animals or if an individual cat has an infection that is poorly responsive to treatment.
If the disease is caused by a virus, the specific causative virus can usually be identified by collecting samples of cells and discharges from the nose, eyes or back of the throat. C. felis organisms may be identified via conjunctival scrapings. If the infection has spread to the lungs, samples may be collected for examination by a procedure called a transtracheal wash.
If a cat has chronic symptoms of respiratory disease, additional diagnostic testing is warranted. This additional testing will usually include chest or skull x-rays, blood tests, and culture and sensitivity testing of abnormal discharges.
How is an upper respiratory infection treated?
Most cats with an uncomplicated upper respiratory infection can be treated symptomatically at home. Your veterinarian may prescribe an eye medication to be applied topically if your cat has a purulent eye discharge. Although viral infections do not respond to antibacterial drugs, broad spectrum antibacterial drugs may be prescribed in an effort to prevent secondary bacterial infections from complicating the disease, particularly in kittens. Primary bacterial upper respiratory infections caused by Bordetella or Chlamydophila will be treated with specific antibiotics that are effective against these diseases.
"Most cats with an uncomplicated upper respiratory infection can be treated symptomatically at home."
Cats with nasal or airway congestion may benefit from increased environmental humidification, such as being taken into a steamy bathroom for 10-15 minutes several times per day. To minimize irritation from discharges, it is often helpful to wipe them away from the cat's face or eyes with a moist tissue. Since cats with a respiratory infection will have a decreased sense of smell, they often have a decreased appetite - feeding a highly palatable canned food may help improve their appetite. In some cases, an appetite stimulant may be prescribed.
If a cat is dehydrated, depressed, or has a severe case of illness, your veterinarian will recommend hospitalization for more intensive treatment, including intravenous fluids and other supportive treatments.
How can this disease be prevented?
Since upper respiratory infections can be caused by a variety of different disease agents, it is not always possible to prevent upper respiratory disease in cats. However, the standard 'core' vaccines that are given to cats provide protection against feline viral rhinotracheitis and feline calicivirus. There is also a vaccine that protects against feline chlamydiosis; this vaccine is considered to be 'non-core' and its use is recommended if your cat has a reasonable risk of exposure to this disease. None of these vaccines will completely prevent an infection from occurring if your cat is exposed to the disease, but they will significantly reduce the severity of the infection and shorten the length of the illness.
All of these vaccines need to be boostered on a regular basis - your veterinarian will advise you on the recommended booster schedule for your individual cat.
Susceptible cats can get an infection by direct contact with another infected cat or by environmental exposure to objects such as brushes, food bowls, litter boxes, cat toys, or blankets that have been contaminated with infectious secretions. Boarding facilities, humane societies, animal shelters, and cat shows are all places where susceptible cats can be readily exposed to these infectious diseases. Preventing direct contact between your cat and other cats will greatly minimize the chance that your cat will pick up an infection, while following good sanitation and hygiene practices, such as washing your hands thoroughly before and after petting another cat will further reduce the likelihood of disease spread between cats.
Are other cats in the household at risk of infection?
A cat that has an acute upper respiratory infection will be infective to other cats during the incubation period and for up to 3 weeks after developing symptoms. A cat that is a carrier of an upper respiratory virus may always be infective to other cats (see question "How long does a typical upper respiratory infection last?"). Cats that are unvaccinated, are young, or have chronic underlying problems are more susceptible, and may develop a serious illness. Adult cats that have been adequately vaccinated will likely only develop a mild case of illness, which may resolve without treatment.
"A cat that has an acute upper respiratory infection will be infective to other cat..."
It is always prudent to isolate a new cat from the other cats in your household for at least 1-2 weeks to minimize transmission of any infectious diseases.
Is my family at risk?
Most of the infectious diseases that cause upper respiratory infections in cats are very species specific and do not represent any risk to people.
Bordetella bronchiseptica can cause illness in people with immune system disease. There are isolated reports of people who live in the same household as an affected cat developing C. felis-associated conjunctivitis. Follow good hygiene practices to lessen the chance of infection, and if anyone in your household develops sore or runny eyes or signs of a respiratory infection while your cat is ill, it would be prudent to consult your physician. You should realize that these 'zoonotic' infections are rare.