Diseases, Vaccines

Upper Respiratory Infections in Cats

The feline respiratory tract is a weak spot in the cat. That weakness is why vaccines favor respiratory viruses. We discuss the virus cause but often it is two viruses and secondary bacteria that complicate the recovery. Knowing what caused the issue does help prevent future episodes in this cat and future kittens, so we will start with common respiratory viruses.

What Causes Respiratory Infection in Cats?

Viral Causes

Herpes/Rhinotracheitis Virus:

  • When we talk about respiratory disease in cats, everyone wants to talk about Herpes. Herpes is the number one cause of feline upper respiratory infections (URIs) in cats. Herpes is forever – once cats get it, they will carry it for the rest of their life. Studies estimate between 70 percent and 90 percent of cats carry the Herpes Virus. Herpes affects the cornea of the eye in cats and kittens, and if untreated, severe ulceration can cause the loss of the eye. Often Herpes and Calicivirus are both present in young kittens.


  • Vaccinating for Calicivirus is important because the virus can stay alive in the cat, hidden in the nervous system, with no clinical signs until the conditions are right for it to reproduce. In situations of mixed infections, Herpes often infects the respiratory tract, and Calici will infect other tissues in the body. As a result, Calici often affects tissues of the joint, bladder and GI tract. It also often results in ulcers of the mouth and nose. Cats can shed Calicivirus in their feces or urine, but they can also shed it with coughing and discharge from the nose and mouth. Though Herpes will only last a few hours in the environment, Calici can survive for as long as a week, which means disinfecting is important.

Feline Leukemia/Feline Immune Deficiency Virus:

  • If cats are infected with Feline Leukemia Virus, they are often prone to complicated bacterial pneumonia and rhinitis. This virus and Feline Immunodeficiency Virus suppress the immune system, disabling cats from fighting respiratory infections and complicating treatment. If the FeLV/FIV status is unknown in your cats, you should test them before initiating treatment.

You can see viruses by themselves or together, but many respiratory infections are complicated with bacterial infections. Bacteria always resides in the respiratory tract, and they stay in check when the cat is healthy. However, when the cat is sick and the immune system is busy fighting the virus, the bacteria seems to explode. Cats sometimes beat a virus, then die of pneumonia from secondary bacteria.

Secondary Bacteria

Bacteria can also cause issues by themselves. The two most common violators are Chlamydia and Bordetella, but Strep is also seen.


  • Often referred to as “pink eye” because of the conjunctivitis it causes – the swelling of the conjunctiva can be severe. Since this infection is a bacteria within the cells, antibiotics must penetrate the cells of the conjunctiva to be effective.


  • Causes runny nose, eyes, sneezing, and pneumonia. Bordetella can pass back and forth from dog to cat, so it can be a constant problem for shelters in both species.
  • In the shelter or show cattery, the Bordetella vaccine will help control and eliminate the persistent feline URI/pneumonia issue seen with Bordetella.


  • Bacteria lacking a cell wall that invades cells.
  • Causes conjunctivitis and swelling of conjunctiva, sneezing, runny nose, coughing, fever, swollen lymph nodes, and less often Horner’s Syndrome (elevation of the third eyelid) and joint swelling.


  • Strep is uncommon, but when cats are exposed to humans with strep throat, it can affect them as well. If it reoccurs, the humans may need to be treated at the same time to eliminate the problem.

Treatment for cat respiratory diseases requires two angles: support for the cat’s immune response to the virus and prevention of pneumonia from secondary bacteria. Several studies have shown that letting the virus run its course without an antibiotic is a recipe for treatment failure – bacterial issues will complicate the virus.

How to Treat Respiratory Infection in Cats

  • Vaccines help with the severity of Herpes and Calici by giving prior protection. Though vaccinated cats can still get and carry the virus, the disease is less severe and seldom needs treatment. Use the Revival Vaccine Finder to help choose the best vaccines for your cat.

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  • Antibiotics are commonly used with URI in cats, including Amoxicillin or Doxycycline. For uncomplicated viral infections, Clavamox® is the drug of choice, while Chlamydia responds well to Doxycycline. Mycoplasma can be treated with Doxycycline or Azithromycin.
  • The antiviral medication Famciclovir can be used in the case of an acute herpes virus flare up to help the virus go back into remission. L-Lysine supplements, such as Viralys Lysine products, easy-to-give Enisyl-F® Lysine Paste, or Vetri Lysine Plus help support healthy immune systems in cats. However, these supplements are less effective with an active URI. Litters that are just breaking with respiratory infections will respond to L-lysine orally, so if one kitten is diagnosed with a virus, the rest should be supplemented immediately. Chronic Herpes cases stay in remission more reliably with L-lysine, allowing for a much healthier cat.
  • Eye ointments, such as Terramycin®, Vetericyn® or erythromycin ophthalmic ointment, will soothe and speed recovery from eye issues. Ointments are helpful in healing ulcerated eyes, especially with complicated Herpes infections.
  • Soft foods are important in keeping kittens eating. They’ll stay away from dry food because oral ulcers and sore throats make swallowing painful. You can also use Sucralfate, which coats the ulcer to allow the kitten to eat for a short time without pain. However, don’t use it within two hours of antibiotics, as it may slow the absorption from the gut.
  • Heating up wet food slightly in the microwave can increase the aroma for cats that have stuffy noses and entice them to eat. For no appetites, try adding flavor that has an odor. Zesty Paws Wild Alaskan Salmon Oil is a good choice for cats that can’t smell and older cats that have lost their sense of smell.

Cat Having Trouble Breathing Through Nose: Cat Nose Stuffed Up

Cats with respiratory problems have difficulties smelling and as a result, they will be less likely to eat. Use gentamicin ophthalmic solution as a nose drop to open the airway. A few drops in each nostril will cause them to “sneeze” the junk out before feeding. Use of a nebulizer with either saline solution for cats or gentamicin or amikacin injectable solution can also help open nasal passages. In addition, babies can’t nurse if they can’t breathe through their nose. If kittens are not nursing well, flush their noses with nose drops – it works!

If your cat is suffering from respiratory problems, keep in mind that there are probably more issues. Instead of treating the primary infection, make sure you attack the secondary bacterial and eye problems as well. When problems affect a whole litter or spread to a chronic disease, L-lysine can be the boost you need for treatment success.

If you need help with cat respiratory problems, call our Pet Care Pros at 800.786.4751.

Last updated by Amy Hanson, DVM. Amy Hanson, Doctor of Veterinary Medicine, is an associate veterinarian at the Cat Clinic of Lawrence in Lawrence, Kansas. She is a 2010 graduate of Kansas State University College of Veterinary Medicine. Her special interests include felines, acupuncture and dentistry. Her hobbies include showing cats and she is a judge for the American Cat Fanciers Association (ACFA).

Written by: Donald Bramlage, DVM

Donald Bramlage, Doctor of Veterinary Medicine, practiced veterinary medicine for 30+ years and is known for his work in managing parvovirus. He received his Doctor of Veterinary Medicine from Kansas State University in 1985. He served as Revival’s Director of Veterinary Services from 2011 until his retirement in 2019.

If you need help, call us at 800.786.4751.