Respiratory infections are commonly the reason why cats visit the veterinarian. Multiple viruses, bacteria, and occasionally fungi cause these infections, which lead to sneezing, eye discharge, and general discomfort. Cats with respiratory infections probably feel similar to a human with the common cold, and their infection can easily spread to other cats through respiratory secretions. The Star of Texas Veterinary Hospital team wants cat owners to understand why cats get respiratory infections and how they should be treated.

What causes cat respiratory infections?

The vast majority of respiratory infections affect the upper respiratory tract, and are commonly known as upper respiratory infections (URIs), but kittens, seniors, and cats with compromised immune systems sometimes develop more complicated lung infections that require more extensive treatment. Most infections are viral, bacterial, or both, but fungi occasionally are to blame. Here are the most frequent agents that cause respiratory infections in cats:

  • Feline herpesvirus type 1 (FHV-1) — Also called feline viral rhinotracheitis, this virus infects the vast majority of cats at some point, and most commonly causes feline URIs. The virus initially infects kittens or young adults, causing symptomatic infections, and then becomes dormant in nerve cells, but can reactivate later in life from stress or concurrent illness. Cats with reactivated virus can spread the illness, and may suffer from chronic or recurrent eye ulcers along with typical respiratory signs. This infection is extremely common in all cats, but especially those from shelters, large breeding catteries, or feral colonies.
  • Feline calicivirus — This virus, which affects around 10% of normally housed cats and up to 90% of cats in shelters and other crowded environments, frequently causes typical respiratory signs and mouth ulcers, but may progress to lung infection. Rarely, this virus can spread systemically and result in death.
  • Feline chlamydiosis — This bacteria, which is responsible for around 20% of respiratory infections, typically causes significant conjunctivitis, and spreads through eye discharge secretions. Sometimes, bacterial infections occur secondary to viruses.

Other, less common, respiratory pathogens include a fungus that invades and damages the nasal passages, and the canine kennel cough bacteria (i.e., bordetella). 

What are cat respiratory infection signs?

Infection signs vary slightly depending on the causative agent, but often include:

  • Sneezing
  • Nasal discharge
  • Mouth ulcers—common in calicivirus
  • Eye ulcers—common in herpesvirus
  • Coughing
  • Lethargy
  • Poor appetite

Signs of more advanced respiratory infections—which require immediate veterinary care—include fever and difficulty breathing. 

How are cat respiratory infections diagnosed?

Your veterinarian can diagnose a respiratory infection based on history and physical examination, but may recommend additional testing in severe or recurrent cases to identify the specific organism causing the infection, and to rule out lung involvement and underlying diseases impacting immune function. Testing may include nasal or eye swabs that are sent to the laboratory, chest X-rays, or blood work.

How are cat respiratory infections treated?

Treatment depends on infection severity and identification of the causative agent. Mild viral infections often resolve on their own, but your veterinarian may prescribe antibiotics that reduce the chances for a secondary bacterial infection. If bacteria are the suspected primary cause, antibiotics are a must. Herpesvirus infections, especially recurrent infections that occur later in life, may require systemic oral medications and eye drops to treat ulcers and conjunctivitis. Cats with mouth ulcers may require dental treatment or tooth extractions to reduce long-term complications.

Stress reduction is important in treating URIs, because the immune system cannot function properly when cats are stressed. Removing stressors from the home is a good place to start, and pet owners must work closely with their veterinarian to ensure the treatment plan is not making the cat more stressed and making things worse. Probiotics are a novel treatment option that may boost immune system function and help cats experience fewer URIs in their lifetime.

Can you prevent a respiratory infection in your cat?

Keeping your home as stress-free as possible will help to reduce URI incidence—visit to learn how to create a stress-free, cat-friendly home. Most cats are vaccinated for the common respiratory pathogens because they are often included in the “feline distemper” combination series, but these do not prevent infection entirely, although they can reduce severity and spread. Avoid boarding your cat in large facilities whenever possible.

The same way people frequently have common colds, many cats get respiratory infections. Most infections are self-limiting or easily treated with supportive care, but some may become serious. If your cat shows respiratory signs that don’t resolve after several days, or they are so uncomfortable that they stop eating, contact the Star of Texas Veterinary Hospital team to schedule a visit and help your cat on the road to recovery.