October 16, 2023
Feline Upper Respiratory Infections

How they come about, treatments and preventative options.
Feline Upper Respiratory Infections

Some of us cat parents may have heard the phrase feline upper respiratory infection at the vet clinic or from friends and family and it sounds like a mouthful and a little scary. We want to take away some of the fear and mystery and explain what it is and what we can do to help our purrfect friends. First off, the upper respiratory tract includes the nose/nostrils and nasal cavity, mouth, throat, voice box and the mucosal membrane that lines the whole system. Feline upper respiratory infection (URI) is the common term for a respiratory infection caused by one or more viral or bacterial agents within the upper respiratory tract. It may also be referred to as feline infectious respiratory disease or feline upper respiratory disease complex. Typically, the most consistent symptoms include sneezing, coughing, nasal congestion, conjunctivitis (inflammation of the membrane lining the eyelids), and discharge from the nose and/or eyes. This discharge may be clear or cloudy in colour. There are also a few general symptoms that you may also see with other illnesses. They may experience lack of appetite, lethargy, fever, enlarged lymph nodes, squinting and in severe cases, difficulty breathing.

Cats will experience inflammation and drainage in the mucous membranes of their nose and throat. This drainage is the body’s defenses trying to flush the infectious material from the body to eliminate the infection. The excessive sneezing, coughing and secretions also help to spread the infectious material from one cat to another. Most URIs are not considered a medical emergency, however, severe URIs can lead to depression and lack of appetite. This can be fatal for young kittens or senior cats who grow weak quickly without proper nutrition and adequate hydration. It is unfortunately common in URIs for the patients to contract an additional infection as their immune system is dampened, and the secondary infection may be more severe and require hospitalisation.

The Cause

Feline upper respiratory infections can be caused by different viruses and/or bacteria. The most common viruses that cause URIs in cats are feline calicivirus (FCV) and feline viral rhinotracheitis (FVR), also known as feline herpesvirus type 1. The most common bacteria that cause URIs are Bordetella bronchiseptica (B. bronchiseptica) and Chlamydophila felis (C. felis). There are less common agents such as mycoplasma and feline reovirus. With this said, FCV and FVR are the most concerning because they are responsible for approximately 90% of feline URIs. Now, how do our cats become infected? The viruses and bacteria that are responsible for URIs in cats are highly contagious. An infected cat will shed the contagious materials in the saliva or secretions from their nose or eyes. Other cats are susceptible from direct contact as cats love to groom each other, and this makes it more of a concern with shelters and multi-cat households. Our cats can also be exposed through aerosol transmission where the infectious particles are released into the air through sneezing and coughing. It can also be transferred through fomites, which are objects that have been contaminated by one cat and then that object is exposed to uninfected cats. These objects can include kennels, food & water dishes, bedding, toys, and litter boxes. Environmental exposure is also a higher concern for those will multiple cats. It is thought to be more likely to contract URIs through direct contact and not as common through the environment. This is due to the fact many viruses and bacteria only survive a limited time in the environment and are also destroyed with disinfectants. FVR can survive less than 18 hours outside the host’s body while FCV can survive for up to 10 days and can survive laundry detergents that do not contain bleach. It is a good decision to take some extra precaution and disinfect all common items regardless.

Infectious Period

When talking about exposure to infected cats, whether direct or through the environment, we also need to think about how long they are contagious for and when is it safe to bring them around other cats. Once exposed our furry friends will go through an incubation period before they develop any clinical signs for us to pick up on. The incubation period is typically 2-10 days. In most cases the infection and clinical signs will last for 7-10 days after the incubation period, but signs can persist for up to 21 days in some cases. It is this entire period where the infected cat could be exposing other members of the house, boarding facility, or shelter.

Carrier State

The carrier state is a concern since the carrier cat no longer shows any clinical signs but is still contagious. With FVR, all cats become chronic carriers, meaning they will have the virus for life. For the most part, the virus would be dormant, and they would not suffer from any symptoms but periods of stress from illness, surgery, change in environment can reactivate it. With FCV, about 50% of infected cats will become carriers of the virus. In many cases the carrier state only lasts a few months with FCV, but in a small percentage of cases they will be a carrier for life. With FCV the virus is continually shed and does not go dormant. In these cases, the cats are still shedding the viral particles that are infectious to other cats. In addition, female carriers of either virus can pass it to their kittens without showing any symptoms themselves.

Most Susceptible

There are certain aspects that can make a cat more susceptible to feline upper respiratory infections than others. This includes kittens and senior cats who have less robust and effective immune systems. Cats may also have an underlying condition taxing their immune system, making them more susceptible as well. Those with a diagnosis of feline leukemia or feline immunodeficiency virus (FIV) are significantly more prone to URIs as their immune system is already strained so much. Some breeds of cats are more prone to URIs due to facial structure. Breeds with shortened noses or “smushed” faces have shorter bones in the skull causing the pushed in appearance, these breeds are called brachycephalies. Due to this facial structure, Persians, Himalayans, and Burmese have a limited ability to clear mucus containing viral or bacterial materials of a URI. This means cat parents of these breeds may want to take further preventative measures, and if contracted the URI may take longer to clear their system. Shelter cats and multi-cat households are more at risk as well since cats are infectious prior to showing any symptoms. It is very difficult to isolate the sick individual before any others contract the infection. We all love the freedom of being outside and unfortunately for cats this does put them at more risk. They are more likely to come in contact with an infected cat than and indoor only cat would. Of course, these points are only to bring awareness and does not mean your cat is guaranteed to contract a URI if they match some of these criteria.


It may be surprising that with URI cases diagnosis is done through a physical exam and typically no diagnostic testing is required. Diagnosis is mostly based on the clinical signs such as the runny nose and eyes, sneezing and conjunctivitis. Identifying the causing agent, which bacteria, or virus, is not always necessary unless they are not responding to treatment and may also be recommended in breeding cats. To identify a viral agent, they can collect samples of cells from the discharge at the eyes, nose and back of the throat to be sent off for testing. Depending on the symptoms exhibited, veterinarians may be able to identify to a certain extent whether it is FCV or FVR. FVR will typically cause red and swollen mucous membranes of the eyes and nose as well as an inflamed larynx and trachea. While FCV may create ulcers of the oral mucosa and lesions on the tongue or hard palate. When it comes to Chlamydophila felis, organisms can be identified through conjunctivitis scrapings.

If symptoms are long lasting or reoccurring, further diagnostic testing may be recommended. The additional testing could include chest and/or skull x-rays, blood tests, bacterial culture & sensitivity testing, and PCR testing of the abnormal discharge. X-rays also help to confirm that there is not lower respiratory involved like pneumonia. The veterinarian may want to rule out any underlying concurrent infections such as feline leukemia and FIV through quick and simple snap tests using a small blood sample. The more thorough testing for more severe cases helps them create a more targeted treatment plan for the specific viral or bacterial cause.


Most cats who have a URI can be treated symptomatically at home. This means that the veterinarian may prescribe medications to treat the specific symptoms each cat is experiencing such as eye drops, or nose drops for cloudy discharge, but many cats can recover with intervention from home. If the cat is not eating well the veterinarian may also prescribe an appetite stimulant. Whether it is a viral or bacterial URI, the veterinarian may prescribe broad spectrum antibiotics. A viral infection does not respond to antibiotics, but this does help to prevent any secondary infection occurring while the immune system is burdened, further complicating the condition. If further testing was performed and the URI was confirmed to be caused by either Bordetella or Chlamydophila, it would be treated with specific antibiotics to target the culprit more effectively. It is very important to follow all antibiotic labels exactly as instructed. Do not discontinue the medication before completing the course of treatment and try your best to not miss a dose. If you are ever unsure, please call your veterinarian with any questions or concerns. In severe cases where the cat has become dehydrated, depressed, or is having serious difficulty breathing, hospitalization may be recommended for fluid replacement therapy and/or oxygen therapy.

Apart from medications and hospitalization there are a few things veterinarians recommend that you can do yourself to help with their recovery. For cats that are experiencing a lot of congestion, they may benefit from increased humidification or steam therapy. You can do this by bringing them into the bathroom with the hot shower running for about 10-15 minutes and this can be done several times a day. It is important to make sure they are staying hydrated when doing steam therapy. Additionally, pet parents can use a moist cloth or wipe to avoid further irritation to the nose or eyes while gently wiping away discharge. Since it is common to have a decreased appetite, having a highly palatable wet food will help get them eating and hydrated. Lastly, a probiotic supplement and a Lysine supplement may be recommended to help support the immune system while fighting the infection. The probiotics can also help with any gastrointestinal upset experienced as a side effect for medications like antibiotics.


Since feline upper respiratory infections can be caused by a variety of viral and bacterial agents, it can be difficult to prevent against, but there are a few things pet parents can do to minimize the risk. One prevention method we will look into is vaccinations. Part of the core vaccines recommended to all kittens and cats is FVRCP which helps to prevent FVR, FCV, and feline panleukopenia. There is also a vaccine against feline chlamydiosis (an eye infection caused by C. felis) that is not part of the core vaccines and is usually only recommended if the veterinarian feels they are at a higher risk of exposure to C. felis. Also, there is a rare but serious form of FCV known as hemorrhagic calicivirus but there is an increased risk of reaction with the vaccine and veterinarians will want to ensure you understand the risk and benefits before administering. Since a feline leukemia diagnosis makes cats more susceptible to URIs, it is also a good idea to ask your veterinarian about this core vaccine. The forementioned vaccines would require a booster on a scheduled basis of 1-3 years dependant on the vaccine and vaccine history of the patient. While vaccines are great tools to minimize the risk, none of the vaccines will completely prevent an infection but they will significantly reduce the severity of the infection and shorten the length of illness.

Another way to prevent feline URIs is to minimize exposure. Preventing direct contact between your cat and others greatly minimizes the chance they will pick up any bacteria or virus leading to the infection. Indoor cats are at a great advantage due to their minimal exposure. Unfortunately, cats in humane societies, shelters, boarding facilities, and cat shows have a harder time preventing both direct contact and environmental transmission. It may be surprising to some but we ourselves can be exposing our cats to viral and bacterial agents through hands, toys, and clothing. If you yourself have been exposed to other cats it is a great idea to change our clothes and wash our hands, and of course clean or keep any dishes and toys separate. Minimizing exposure for the first couple weeks of bringing a new cat home is also a great recommendation to consider. This not only helps to minimize stress for current furry family members, but it also gives a chance to monitor for any symptoms and help to prevent an infection spreading to the rest of the home. Most would recommend at least 2 weeks of separation with proper hand hygiene and separate toys and dishes. Some pet parents are extra careful and would wait till the new member is fully vaccinated and has a clean bill of health before direct contact with their new friends.

Boosting the immune system and minimizing stress is another method to help prevent feline URIs. This is especially important for cats that are carriers of viral agents as stress is an added burden to the immune system putting them at a higher risk for viral shedding. You can minimize stress by providing perches to get away or watch out a window. Having a variety of toys for them to play with and lots of space to wonder and relax also helps to prevent stress and therefore, prevents shedding of the virus. A big stressor for cats is a crowded, dirty litter box so it is a great idea to ensure you have enough litter boxes in low traffic areas that are cleaned often. Another way to minimize stress is through pheromone treatment that you can plug into the wall or spray areas like their bed, litter box and perches. There are a few things we can add to their diet to boost their immune system to minimize the risk. As we had talked about before with at home treatments, you can add a probiotic and lysine supplement that helps to strengthen the immune system to then fight off infection. The addition of antioxidants and anti-inflammatories can also help keep the immune system running at peak performance to tackle any viral or bacterial agents ahead.

We hope whether a single cat or multi-cat household, and indoor or outdoor, that we have given you some insight on feline URIs and some preventative methods to help keep all our furry friends as healthy as possible.

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Written By | Taylor Luther
Marketing Lead, Customer Engagement
Taylor completed a Bachelor's Degree in Animal Biology at the University of Guelph and has built up experience within the pet nutrition industry and the animal medical field. She has a passion to share all insights on pet nutrition and health for all of our furry (feathery, scaly or otherwise) friends.