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Upper Respiratory Infections in Cats

Dr. Lila Miller, D.V.M., ASPCA Sr. Director Animal Sciences and Vet Advisor

Runny eyes. Sneezing. Nasal discharge. Loss of appetite. Shelter workers all know the signs. Feline upper respiratory infections (URI for short) are the most commonly encountered disease problem in animal shelters. Some shelters have cases all the time. Others have outbreaks that can only be referred to as epidemics that result in the suspension of feline adoptions. Even the most conscientiously run shelter will suffer from occasional outbreaks. These outbreaks should not be taken as an automatic sign that the shelter’s health care system has failed. A careful evaluation of the health care program should be undertaken to determine what corrective measures are needed to minimize the impact of the disease on the shelter’s feline population. In most instances, elimination of the virus may be impossible and containment of the damage is the goal. Upper respiratory infections frequently cause mild symptoms that can be resolved if the shelter has the resources to isolate the animals, render nursing care and treatment or place them in foster care programs until they are cured of clinical signs. The reluctance to euthanize animals with mild symptoms will contribute to the longevity of the problem and the inability to rid the shelter of infection. Whichever goal is chosen, an understanding of the diseases and disease transmission is essential to start.


Upper Respiratory Infections in Cats


Two viruses, a herpes virus (rhinotracheitis) and calici virus are the two most commonly encountered culprits in upper respiratory diseases. These two viruses account for the vast majority of cases seen, but disease can also be caused by chlamydia psitacci, a bacteria. Recently there have been reports of cases of upper respiratory infections being caused by bordetella bronchiseptica, the same bacterial organism that is responsible for kennel cough in dogs. There is even some evidence that bordetella causes disease in humans.


These diseases have an incubation period of between 2-7 days, the time between infection and the appearance of clinical signs. The virus is shed in various body fluids such as ocular, nasal and oral secretions and discharges. The virus is then spread by 3 mechanisms- 1) mainly from direct contact of sick cats with susceptible ones, 2) through environmental contamination with infected secretions and 3) by carriers. Carriers are cats who continue to harbor and shed virus after they have been infected and recovered from clinical signs.

Aerosolization of the virus occurs, but it is not thought to be a main means of spread of infection. It is also spread by fomites, which are inanimate objects. Fomite spread of disease is believed to be one of the largest contributing factors to how diseases are spread through a shelter. Viral particles that are found in ocular, oral and nasal secretions can contaminate clothing, hands, bedding, toys, food dishes, litter boxes, water bowls, cage floors, stethoscopes, etc. Disease is spread when susceptible animals have contact with these contaminated objects, so isolation of sick animals alone is not a sufficient control mechanism.

Carrier states

The existence of the carrier state is particularly important for shelters that do not euthanize for overcrowding or disease control. Animals that have recovered from acute infections will continue to shed virus and therefore remain infectious for the duration of their stay in the shelter.

Most cats that have recovered from herpes will be carriers of the virus for life and shed it intermittently under normal conditions or during times of stress. This shedding can begin a week after the stressful incident and continue for 3 weeks afterward.

In the case of calici virus, some cats that have recovered from infection will shed the virus continuously for the rest of their lives without regard to stress. Fortunately most cats do eliminate calici virus from their bodies eventually.

Bordetella and chlamydia:
It is believed that there is a carrier state with bordetella and chlamydia, but the mechanisms are not entirely clear yet.


Most cats with signs of upper respiratory disease suffer from bouts of sneezing and runny eyes. In most cases, shelters do not bother to distinguish between the different disease causing agents. However, it is important to make the distinction in order to design effective control measures, such as vaccination or treatment protocols.

The lethargy, sneezing, ocular and nasal discharges may be worse with herpes than the other diseases. Herpes is also accompanied by fever, depression, loss of appetite, eye ulcers and drooling.

Calici virus produces oral ulcers and lameness. These may be the only signs or they may be seen in combination with the same signs as herpes, only milder.

Chlamydia produces a serious conjunctivitis (eye infection), accompanied by mild sneezing. This same organism may cause conjunctivitis in humans.

Bordetella is still being researched. It is believed to cause fever, sneezing, nasal discharge, enlargement of the lymph nodes found under the throat and loud, harsh lung sounds. Coughing may also be observed.


Diagnosis is generally made based on the clinical symptoms. Cultures from the mouth, throat or nose may be sent to the laboratory for confirmation.


Treatment for the viral diseases is symptomatic.

Good nursing care (wiping away ocular and nasal discharges, force-feeding, keeping warm, etc.)

Broad-spectrum antibiotics to protect against secondary bacterial infections. Tetracycline or doxycycline are the drugs of choice to use against bordetella and chlamydia and may also be used in the case of the viral infections.

Fluid therapy may be necessary in severe cases.
Antiviral drugs may be necessary in the form of eye drops for herpes viral induced eye lesions.

Feeding: Cats who are unable to smell their food as a result of the infection may lose their appetite and refuse to eat, so they must be encouraged by offering foods with strong aromas, baby foods or other soft and blended foods. It may be necessary to place a nasogastric tube to force feed them if they continue to refuse to eat.

Steam inhalation or nebulizers may also be helpful.

Shelters must consider carefully the resources they have available and the risk to healthy cats when undertaking treatment. A cat who needs only minimal treatment to recover from an upper respiratory infection may pass it on to another cat who requires intensive care therapy. Once the shelter has run out of space to isolate sick animals or place them in foster care, it may be necessary to consider euthanasia to protect the lives of the rest of the animals.


It is critical to disinfect the environment to control these diseases. Fortunately, these organisms do not live long outside the cat’s body and they are all fairly susceptible to chemical destruction. For example, herpes virus persists outside the animal’s body for only about 18 hours and is easily destroyed by most disinfectants. Calici virus can persist for up to a week or longer in a damp environment and is slightly more resistant to disinfectants. Chlamydia is unstable outside the host’s body and can survive in ocular discharges at room temperature for several days. This compares favorably with a virus like parvo, which can persist in the environment for several months and is resistant to most disinfectants.

The cat should be removed from the cage along with all other items in the cage. The entire cage must be then cleaned with soap and hot water, including the bars in the front, sides, floors and tops. The disinfectant should be applied and allowed contact with the surface according to the manufacturer’s recommendations, and then rinsed. The cage should be completely dry before the cat is returned.

Sodium hypochlorite or household bleach is one of the most effective and inexpensive disinfectants available. If diluted 1:32 with warm water, it will not be corrosive to the cage surfaces or act as an irritant to the cat’s mucus membranes.

Staff, volunteers and the public should be instructed to avoid handling or touching animals unless they wash their hands thoroughly after each contact. (This includes just sticking the finger in the cage and touching each cat’s nose!)

Shelter Design

Cage placement and ventilation has a lot to do with the spread of disease. A cat’s sneeze can travel about 3-4 feet, so it is important to have cat cages at least 4 feet apart if they are facing each other. Shelter traffic patterns should place as much distance as possible between sick wards and healthy ones.

Lack of adequate ventilation also plays a key part in disease spread as well. If an air exchange system is employed, there should be a minimum of 12-15 air changes per hour, preferably with outside air. If not, circulation patterns should go from healthy areas and kitten areas to sick areas. Hepa filters may be helpful, but should not be relied on to counter inadequate ventilation systems.

Prevention and Disease Outbreak Management

The following other measures should help prevent and minimize the impact of upper respiratory infections:

Quarantine incoming animals for 2 weeks, especially if in group or colony housing

Isolate sick animals immediately

Vaccinate all cats beginning at 8 weeks of age for kittens, with boosters every 3 weeks until 12 weeks old. Consider using an intrasnasal vaccine if URI is a problem. Many shelters report excellent results in reducing the incidence of URI when switching vaccines from the injectable. Intranasal vaccines can be used in animals as young as 3 weeks of age if using the bivalent product against calici and herpes virus. The main advantage is that a faster immune response is seen compared to use of the injectable vaccine. The main problems with the intranasal vaccines are that they are harder to administer and cause side effects that mimic actual clinical disease. The difference is that the animals with vaccine reactions still appear well and only sneeze and have runny eyes for a couple of days. Adopters of animals who have been given this vaccine should be advised of the side effects so they and their veterinarians will know what to expect.

Although still highly controversial, some shelters also report a decrease in the incidence of URI after using the intranasal bordetella vaccine. Positive cultures of bordetella should be obtained before using this product.

Deworm kittens and cats routinely

Feed the best diet affordable, and for individual needs

Segregate kittens by litter and age groups. Kittens under 3 months of age are most susceptible to disease and should be separated from other litters and from adult animals

Clean and disinfect cages daily with a safe, effective disinfectant or bleach diluted 1:32 with water

Disinfect water bowls daily and between each animal

Instruct staff, volunteers and visitors about spreading disease via fomites
Use hand sanitizers and footbaths in the wards
Post signs asking the public to prevent disease spread by washing their hands and to avoid handling animals without staff supervision

Use disposable litter pans, toys, cleaning cloths and food dishes

Restrict the use of cleaning materials to individual rooms or wards

Launder uniforms in hot water, detergent and bleach

Reduce stress!

Avoid overcrowding, loud noises
Provide bedding, toys
Establish a routine for cleaning and other procedures
Maintain comfortable environmental conditions, including adequate ventilation

Place mildly affected animals in foster homes where treatment can be continued without exposing all the animals to risk of infection

Consider euthanasia when the ability to isolate, place in foster care or treat is exhausted.

Courtesy of
424 East 92nd St.
New York, NY 10128-6804
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