Upper respiratory infections are a frequent cause of illness in kittens, cats in a shelter environment, cats who spend time outdoors, and in Persian cats at any age. Clinical signs can range from mild sneezing to complete crusting of the eyes and nose with open mouth breathing and may even progress to pneumonia. Just like the common cold in people, URIs (upper respiratory infections) in cats are caused by various infectious agents. The most common causes, accounting for approximately 90% of cases, are feline herpesvirus and calicivirus. The fact that these are both viruses and, as such, do not respond to antibiotics, will come into play as we discuss treatment options. Other causes include Bordetella, Mycoplasma, and Chlamydophila, which are all bacterial infections. Infection by multiple agents is common. Infections are easily spread between cats and the infectious agents can persist as long as 10 days in the environment. Furthermore, once a cat has recovered from a URI, they may continue to shed infectious agents into the environment for many months. Finally, the viral upper respiratory infections lead to a permanent carrier state. While your cat is likely to heal fully from an upper respiratory infection, they are at a significantly elevated risk for a return of the signs through their life (especially during times of physical and mental stress), as the virus is never completely cleared.
The signs caused by upper respiratory infections include eye discharge (watery, thick, or crusty), squinting, nasal discharge (watery, thick, or crusty), corneal ulcers (wounds to the surface of the eye), sneezing, wheezing, a change in the sound of your cat’s meow, oral ulcers, and open mouth breathing. Kitties who are sick with a URI can also develop high fevers, lethargy, and loss of appetite. Rarely, pneumonia can occur. If you notice these signs developing, please call your vet. If the signs are mild, they may advise monitoring at home. They may also tell you that bringing your cat in for examination is best. At this visit, they will discuss what has been happening, check your cat’s temperature, carefully examine her eyes and mouth, and listen to her heart and lungs. Based on what they find on examination, x-rays of the chest and lab work may be offered.
As discussed, most upper respiratory infections are caused by a virus. That being said, secondary bacterial infections are common. Treatment of mildly affected cats usually involves at home supportive care in the form of maintaining interest in food by warming it/offering “stinky” foods, steam treatments/humidified air, and close monitoring. In cats with more severe infections, loss of appetite, or a fever, antibiotics are likely to be prescribed. If your cat has corneal ulcers, you will be sent home with topical eye medications and an e-collar (cone) to prevent further trauma to the eye(s). In some cases, antiviral medications will be prescribed. Prognosis for cats with upper respiratory infections is quite good, but it may take as long as two weeks for your pet to recover.
There are many steps that can be taken to reduce the risk of an upper respiratory infection in your cat. Firstly, core vaccines include vaccination against herpesvirus and calicivirus. Keep your cat indoors and limit your kitty crew to just a few cats. If you are introducing a kitten to your family, be sure that the kitten is well quarantined from your other cats for the first few weeks. Supplementation with the amino acid lysine may reduce severity and frequency of herpesvirus flare-ups. Reduce stress where you can – just like in people, stress is a known trigger for flare-ups of herpes infections.
As always – contact your veterinarian with any questions or concerns about your pets’ health!
For more information on the MSPCA-Angell West Emergency Service, please visit www.angell.org/emergency or call 781-902-8400.