Why wont my cats upper respiratory infection go away?

You may have heard your veterinarian talk about upper respiratory infections in cats before, but what are they and how do you know if your cat has one? Upper respiratory infections, otherwise known as URI, are a very common occurrence in domestic cats.

What Are Upper Respiratory Infections in Cats?

Cats develop upper respiratory infections from exposure to viruses and bacteria that cause sneezing, eye discharge and a whole host of other symptoms. These upper respiratory infections are very contagious since cats can be infected with both viruses and bacteria at the same time. Symptoms can range from mild to severe.

The most common type of URI in cats include Feline Herpesvirus Type-1 (also called feline viral rhinotracheitis, or FVR) as well as Feline Calicivirus, according to Pet Health Network. Bordetella bronchiseptica and Chlamydophila felis are the most common bacterial causes.

How Do These Infections Spread?

Typically, an infected cat will sneeze and spread the virus and/or bacteria in secretions from the nose, eyes or saliva. The infection can be spread from cat to cat, or by exposure to fomites, which is a technical term for any object that can carry virus or bacteria. Fomites can include food and water bowls, litter boxes, bedding, toys, carriers, cat trees, cages and even you!

Cats infected with herpesvirus become carriers of the virus for life. This means that they will carry the virus in a dormant state for their whole life, but they won't show signs or be contagious unless the virus is reactivated by stress. Sources of stress can include moving, boarding, other illness, surgery or introducing new cats to the home. Cats infected with herpesvirus do best in a quiet home where they are the only cat.

About half of the cats infected with calicivirus will carry the disease for a couple of months, a few may carry it for life. The concern with persistent carriers of herpesvirus and calicivirus is that these cats will not show symptoms but may still infect other cats.

Signs of Upper Respiratory Infections in Cats

In most cats, uncomplicated URIs last about 7 to 21 days. If your cat is immunosuppressed (meaning their immune system has trouble fighting infections) or has other issues, the URI may last longer. Once a cat is exposed, the virus or bacteria incubates for 2 to 10 days, and then symptoms develop. A cat is considered contagious the whole time.

Signs of upper respiratory infection in cats may include:

• Sneezing
• Fever
• Loss of appetite
• Low energy
• Red eyes, swollen eyelids or eyes swollen shut
• Snot
• Eye discharge — either clear, green, white or yellow
• Bad breath

Diagnosing Upper Respiratory Infections in Cats

Most of the time, cat upper respiratory infections are diagnosed by physical exam and history from the owner. Usually, the individual bacteria or virus is not identified unless the cat is not responding to treatment.

Your vet will conduct a complete physical exam and gather an oral history from you. If testing is required, usually a swab from the eye, nose or back of throat is collected. In rare cases, additional testing such as X-rays, blood tests and culture testing may be recommended.

Is My Family at Risk?

With rare exception, most of the infectious agents that cause URIs in cats will not pose an infection risk to people — they only infect cats. The exception is Bordetella bronchiseptica, which can, in rare cases, cause problems for people who are immunosuppressed. If anybody in your household develops signs of an upper respiratory infection or skin sores while your cat is sick, consult with your physician, and always use good hygiene practices to prevent the spread of disease.

Treating Upper Respiratory Infections in Cats

Thankfully, many times URI cases have generally mild signs that will resolve on their own over time (much like if you caught the common cold). However, if your cat has colored eye or nasal discharge, your vet may prescribe antibiotics, either orally or in a topical eye. If your cat is not responding, then your vet will change medications as indicated to appropriately treat the infection. If your cat only has mild sneezing or clear eye discharge, your vet may not recommend needing to use antibiotics.

Most cats with upper respiratory infections can be treated at home. If they are congested, providing humidification through steam treatment two to three times per day will help loosen secretions. You can easily provide steam treatment by shutting your cat in the bathroom for 10 to 15 minutes and turning the shower on hot so that it produces a lot of steam.

If your cat is experiencing nasal or eye discharge, gently clean it up using a warm, moist hand towel. When cats have upper respiratory infections, they may not have much of an appetite. Providing your cat with extra delicious canned food during this time is a good way to care for your cat. Canned food can be warmed up to increase the aroma, and has the added bonus of providing more moisture to your cat. If your cat still won't eat for more than a day or two, talk to your veterinarian about appetite stimulants.

If a cat is dehydrated, fluid therapy in the form of subcutaneous fluids or intravenous fluids may be recommended. Some cats are so sick that they must be hospitalized, but you can avoid this by seeking veterinary attention as soon as possible if your cat displays signs of a URI. However, keep in mind that URI infections are highly contagious between animals. Thus, you should notify your vet prior to arriving if you suspect your cat has a URI, so they can take necessary precautions to keep other animals at the hospital safe, especially those that may have a compromised immune system.

Keep your cat away from any cats that display signs of upper respiratory infection, and keep your cat up-to-date on vaccinations, which protect against several infectious causes of feline upper respiratory infections.

Dr. Sarah Wooten

A 2002 graduate of UC Davis School of Veterinary Medicine, Dr. Sarah Wooten is a well-known international speaker in the veterinary and animal health care spaces. She has 10 years experience in public speaking and media work, and writes for a large number of online and print animal health publications, such as chewy.com, petMD, Vetstreet, Hill's Education Blog, and DVM360 print and online publications, Healthy Pet Magazine, and the Bark. Dr. Wooten has spoken in the veterinary education space for 5 years, and speaks on leadership, client communication, and personal development. Dr. Wooten is also a certified veterinary journalist, a member of the AVMA, and has 16 years experience in small animal veterinary practice. In addition to being a speaker, author, veterinarian, and co-creator of the wildly popular card game 'Vets Against Insanity', she co-owns Elevated Eateries Restaurant group in Greeley with her husband of 21 years, and together they are raising 3 slightly feral mini-humans. When it is time to play, she can be found skiing in Colorado, diving with sharks in the Caribbean, or training kenpo karate in her local dojo. Go big...or go home.

Cat flu, or upper respiratory infection (URI) is a very common disease that can vary considerably in severity, and on occasions can even be life-threatening.

In the vast majority of cases, disease results from infection with feline calicivirus (FCV) or feline herpes virus (FHV, or FHV-1). Clinical signs include sneezing, nasal discharge, conjunctivitis (inflammation of the lining of the eyes), ocular discharge, loss of appetite, fever and depression. Mouth ulcers, coughing, excessive drooling of saliva and eye ulcers may also be seen. Very young, very old and immunosuppressed cats are more likely to develop severe disease and possibly die as a result of their URI, usually due to secondary infections (such as pneumonia), lack of nutrition and dehydration.

What cats are at risk of URIs?

URIs are common, as the causative viruses are widespread in cat populations. Typical risk factors include:

• Cats kept in large groups or colonies such as breeding catteries, rescue centres and feral cat colonies – in these situations the viruses are able to spread easily
• Unvaccinated cats
• Kittens
• Elderly and immunosuppressed cats (e.g., cats with FeLV or FIV infection, or cats receiving immunosuppressive therapy) are more vulnerable to developing severe disease

Causes of URIs in cats

Most cat URIs are caused by infection with one or both of the cat flu viruses:

These two viruses are thought to be responsible for more than 90% of URIs in cats. Other important organisms that may be involved in some cases include:

Clinical signs of URI

The incubation period following infection with FCV or FHV is usually just a few days (2-10 days). After this, typical clinical signs develop which include:

• Sneezing
• Nasal discharge
• Ocular discharge
• Lethargy
• Inappetence
• Fever

The severity of these signs varies considerably – in some cats the signs are very mild and transient, in others they may be very marked and severe. There are some differences in clinical presentation between the two viruses, but these are not sufficient to be able to distinguish them simply from clinical signs:

• FHV infection tends to be more severe, often causing more marked conjunctivitis (eye infection and ocular discharge), and some ulceration of the cornea (the clear part at the front of the eye). FHV may also cause: severe pharyngitis leading to anorexia; inflammation in the trachea; and coughing.
• FCV infection is often milder, with inapparent or less severe ocular signs, but FCV often causes ulceration of the tongue (and sometimes the palate or the lips). FCV may cause a transient arthritis (‘limping syndrome’), usually seen in young kittens, and in very young kittens can cause severe viral pneumonia.

Although FCV and FHV are viral infections, secondary infection with bacteria is common and can contribute to rhinitis (infection in the nose) conjunctivitis, and even lung infections. While most cats will recover from URIs, on occasions they can be life-threatening, and with severe infections the recovery may take several weeks. Some cats may also be left with permanent damage within the nose and may have persistent or recurrent nasal discharge (so-called ‘chronic rhinitis’).

In rare cases, a much more severe and often fatal form of FCV infection may occur. This is associated with particular strains of the virus that are highly virulent and termed ‘virulent systemic FCV’ (vsFCV) infection. Fortunately such infections are very rare (see: Feline calicivirus (FCV) infection).

Diagnosis

Diagnosis by your vet is usually based on the typical signs associated with URIs, and exclusion of other causes. It is possible to confirm a diagnosis and to investigate which virus(es) are involved, but this is often not necessary.

Testing for FCV or FHV involves collecting a mouth or eye swab which is then sent to a specialised veterinary laboratory. Here the virus can be identified through culturing or by a PCR test (a molecular test to show the presence of the viral genes).

Treatment

Treatment of URIs is largely symptomatic and supportive. Your vet may want to do some additional tests if they are concerned about the extent of disease (e.g., the possibility of pneumonia) or if they are worried about complications (such as infection with FIV or FeLV).

Antibiotics are indicated to treat secondary bacterial infections and to try to reduce the damage the infection causes. If nasal congestion is severe and breathing is difficult your vet may also suggest steam inhalation or nebulisation make discharges more liquid and more easily relieved by sneezing.

Affected cats are often reluctant to eat – they will have a poor sense of smell and eating may also be uncomfortable. Using soft, highly aromatic foods (for example kitten foods, fish in oil) that are gently warmed will help to tempt an inappetent cat. However, if anorexia is severe your cat may require hospitalisation for your vet to provide food via a feeding tube. This can be important, as poor nutrition will significantly contribute to disease and slow down healing. Intravenous fluids may also be needed if your cat is not drinking properly, to avoid dehydration. Analgesics may also be required.

Interferons are proteins that are produced in the body, in part to help fight viral infections. Injectable interferons may be used as a supportive treatment (either high doses of recombinant human interferons or recombinant feline interferon) – there is some evidence that this may be of benefit, but it probably needs to be given early in the course of disease for best effect.

There are a number of topical antiviral agents that can help to manage FHV-associated ocular disease (such as trifluoridine, idoxuridine and cidofovir). More recently a drug used to treat human herpes virus infections – famciclovir – has been shown to be safe and effective in cats when given orally. This is a major step forward in managing severe FHV infection in cats.

General nursing is also essential – discharges from the eyes and nose should be gently wiped away using damp cotton wool, and the cat should be kept warm and comfortable.

Carriers

Most cats that recover from infection with URI viruses will become ‘carriers’. Carrier cats usually show no sign of illness but, may shed virus in saliva, tears and nasal secretions, and can be a source of infection to other cats.

Although almost all cats infected with FHV will remain long-term carriers, many of these will never shed significant amounts of virus. Others may shed virus intermittently, especially during times of stress. Some cats may show mild signs of URI again when they shed the virus, but most do not. Carrier cats in a breeding colony are a source of risk to their kittens, as the stress of kittening may induce shedding of FHV.

Most cats infected with FCV remain carriers of the virus, and continue to shed the virus for a period of weeks or months after infection, but the majority (although not all) will eventually eliminate the virus within a few months.

Spread of infection

The viruses associated with URIs are spread in three ways:

• Direct contact with an infected cat showing signs of URI
• Direct contact with a carrier cat shedding virus
• Contact with virus carried on clothing, food bowls and other objects. Large amounts of virus are present in the saliva, tears and nasal discharges and the viruses may be able to survive in the environment and on objects for up to 2 (FHV) to 10 (FCV) days.

Prevention

• Vaccination: The risk of URIs can be dramatically reduced by vaccination against FHV and FCV. These vaccines are important for all cats, irrespective of how they are kept (even if kept totally indoors), as the diseases are so ubiquitous. Although vaccination usually prevents severe disease developing, it cannot always prevent infection occurring and so mild disease may still develop in some cats. FCV has many different strains, and this can cause further problems with vaccination as vaccines will not necessarily work against all these strains. Newer FCV vaccines contain more than one strain in the vaccine to help overcome this problem. This is not an issue with FHV as only one virus strain exists.
• Barrier nursing and disinfection: If there is more than one cat in a household, it is important to try to minimise the risk of infection being spread to the other cats. This is not always possible, but in addition to ensuring that all cats are vaccinated, where possible a cat showing clinical signs should be kept isolated from the other cats (e.g., confined to one room). Separate food bowls and litter trays should be used, and ideally the cat should be kept in a room that has very easy to disinfect surfaces (i.e., not soft furnishing and carpet). These viruses are susceptible to most disinfectants but make sure you check with your vet – some disinfectants (such as phenolic-based products) are not safe to use around cats. Hypochlorite (bleach-based) disinfectants (eg, 5% bleach diluted 1:32) are effective against these viruses, but take care to use any disinfectant carefully – most are irritant to cats if they come into direct contact with the disinfectant.

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