Introduction
Infectious upper respiratory disease (URD) is the most common respiratory syndrome recognized in the cat. It is most common in shelters where many kittens are grouped together. The predominant organisms causing the syndrome are the feline herpes virus and one or more strains of feline calicivirus. These two organisms are responsible for 90% of respiratory diseases in cats.

Transmission
The viruses are spread between infected cats and non-infected cats by direct contact with oral, nasal and ocular secretions; by contact with contaminated objects (food and water bowls, clothing etc.) and occasionally by aerosol spray. Both viruses can be inactivated by bleach diluted 1:32 with water. Infected cats may show clinical signs of the disease or may be clinically normal. Many cats recovering from viral upper respiratory diseases are chronic virus carriers. Clinical signs are generally absent in these cats, but can occur about one week after a stressful event or after treatment with corticosteroids.

Clinical Signs of the Disease
The clinical signs of URD. vary from cat to cat depending on the organism and the cat’s immune system. Sneezing episodes are usually the first signs of viral upper respiratory disease and they are followed in 24-48 hours by conjunctivitis. Within 3-5 days after the onset of signs, the nasal and ocular discharge becomes cloudy and yellow and a cough may be heard due to laryngotracheitis. At this time the cat may stop eating and develop a fever. The acute disease will persist for 2-3 weeks following the onset of signs. Infection may predispose cats to chromic rhinitis. Some cats with calicivirus infection develop oral ulcers and may become lame due to infection in their joints.

Treatment
Treatment for cats with viral upper respiratory disease is supportive care. The type of therapy given to each cat is based on his or her clinical signs. Good nursing care is essential. Affected cats must be kept warm and quiet in a clean, humidified environment, and away from other animals. The discharge from the eyes and nose must be gently cleaned frequently. The cat should be encouraged to eat and drink. A veterinarian should see any cat that is not eating or drinking or has cloudy/colored discharge from the eyes or nose. Many of these cats will have a bacterial component to their disease and may benefit from appropriate antibiotics.

L-lysine is recommended for cats who have upper respiratory disease caused by feline herpes virus. It is most useful in chronic disease and helps to reduce viral shedding. Once or twice daily dose of L-lysine (250-500mg) crushed in the cat’s food can slow the replication of the virus, thus reducing clinical signs and hastening recovery. *DO NOT administer any medication without first consulting your veterinarian!

Prevention
Infection does not impart immunity. The use of vaccines against these organisms is a significant step towards preventing outbreaks of these diseases and in unexposed cats it produces reasonable protection against disease. All kittens should be vaccinated by 8 weeks of age and receive a booster injection at 12 weeks of age. All adult cats should be revaccinated every 12 to 36 months. Unfortunately vaccination does not protect all cats against infection.