Upper respiratory infections (URIs) can be very common in cats, especially kittens and cats living in multi-cat environments like shelters. URIs can affect a cat’s nose, eyes, sinuses, mouth, and throat. Common symptoms include sneezing, runny nose and eyes, fever, weakness, and appetite loss. URIs are most frequently caused by viruses, but there are bacterial URIs too. Here’s a rundown of the most common causes of upper respiratory infections in cats:

Feline Herpesvirus-1 (FHV-1): While similar to human herpes, the feline strain only affects cats. FHV is considered to be the most serious viral cause of URIs in cats. In addition to the usual symptoms, cats can also suffer from significant damage to the eyes and nasal cavity. All infected cats can be carriers of FHV. After an infection, the virus can also go dormant in the cat’s body and then reactivate, especially in times of stress.

Feline Calicivirus (FCV): Like FHV, FCV only affects cats, not humans. It tends to produce a milder URI than FHV, but it can lead to pneumonia in kittens and cause some uncomfortable mouth ulcers in cats.

Mycoplasma Felis: This is a bacteria that is present in the respiratory system of cats. While it doesn’t typically cause a URI itself, it could exacerbate the problem in cats with other infections.

Chlamydia Felis: Chlamydia Felis is a bacterial infection that can cause inflammation of the tissues around the eye, similar to human conjunctivitis, although it cannot be passed to humans.

Cats with FHV cannot usually be cured, although the disease can go into remission. Antibiotics are given to cats with bacterial URIs, and also viral URIs with secondary bacterial infections. Antivirals can be used to treat viral URIs, even FHV. The supplement L-lysine can also be given to cats with URIs. Your vet may also give you anti-inflammatories and topical medications to treat your cat.

Cats that are very young, very old, or have weak immune systems are especially vulnerable to URIs. The risk goes up for cats that frequently come into contact with other cats. You can talk to your vet about getting your cat vaccinated for FHV and FCV.

Interested in learning more? You can download this fact sheet from the Winn Feline Foundation.