If you’ve ever battled a nasty head cold, you’ll remember how miserable you felt. Cats can also develop a bad cold, or feline upper respiratory infection (URI), caused by various viruses and bacteria. For National Immunization Awareness Month, The Meowing Vet teaches pet owners what steps to take if your kitty comes down with a cold and how routine vaccination can greatly reduce your cat’s chance of developing an upper respiratory tract infection.
Read more below…
What is an Upper Respiratory Infection?
A feline upper respiratory infection, or URI, is also termed upper respiratory complex. A URI is self-defined as an infection of the upper respiratory system: primarily the sinuses and nasal cavity and larynx (voice box) with some pharynx (back of the throat), mouth, and ocular (eye) involvement. It’s basically the kitty equivalent of a severe head cold that we humans may experience. Most pathogens which cause upper respiratory infections are extremely contagious amongst cats, so vaccination is imperative to control outbreaks. In severe cases, a URI can spread to the lower portion of the respiratory tract, affecting the trachea (windpipe), bronchi, and lungs as the infection progresses to bronchopneumonia.
Clinical Signs of a URI
The most common signs that your cat may have acquired an infection of the upper respiratory tract include:
- Lethargy, depression
- Fever
- Decreased appetite (anorexia)
- Nasal involvement (rhinitis)
- Sneezing
- Nasal discharge: may be clear (serous) or green (purulent); your cat will likely have some difficulty breathing out of his or her nose
Ocular involvement: Either both eyes or only one eye may be affected; if left untreated, infection can lead to permanent blindness in some severe cases
- Ocular discharge: may be clear or green
- Conjunctivitis (pink eye): inflammation of the conjunctiva, the tissue that covers the sclera (the white part portion of the eyeball) and the inner aspects of the eyelids – signs include: excessive tear production (lacrimation), the eyes may look blood-shot (hyperemia), the eyelids may be swollen (chemosis), your cat may squint or hold the eyes closed (blepharospasm)
- Keratitis: inflammation of the cornea, the clear tissue on the surface of the iris and pupil
- Corneal ulcers: painful sores in the cornea – may squint and hold the eye closed (blepharospasm); can lead to loss of the eye if severe
- Mouth ulcers: the lips, tongue, back of the throat, and even the nose may be affected with painful ulcerations, which make swallowing and eating difficult
- Coughing: can resemble hacking up a hairball
- Drooling (hypersalivation)
In severe cases:
- Difficulty breathing (dyspnea)
- Death
Which cats are most at risk of infection?
Any cat of any age and breed may develop a upper respiratory infection. However, some cats are at higher risk of infection, such as:
- Kittens and young cats as well as geriatric cats
- Unvaccinated cats and kittens: This also means cats who have had a lapse in their vaccine schedule. Just because a cat received his or her kitten shots does not always mean lifelong protection against these infections. Boosters every 1-3 years are vital.
- Outdoor cats
- Shelter cats
- Brachycephalic (flat-faced) cat breeds (such as Persians)
- Cats with feline asthma (a.k.a. allergic bronchitis)
- Cats with an impaired immune system, such as those that are:
- Co-infected with either Feline Leukemia Virus (FeLV) or Feline Immunodeficiency Virus (FIV)
- Battling an infection with feline panleukopenia (a.k.a. feline parvovirus, or feline distemper)
- Receiving immunosuppressive drugs, such as high-dose corticosteroids or chemotherapeutic drugs
What’s to blame?: the Infectious Agents of a URI
A feline upper respiratory complex may develop from infection or co-infection with the following pathogens:
- Feline herpesvirus-1 (FHV-1)
- Feline calicivirus (FCV)
- Bordetella bronchiseptica (kennel cough)
- Chlamydophila felis
- Mycoplasma
- Other viruses and secondary bacterial infections
Feline herpesvirus-1 (FHV-1)
Feline herpesvirus-1, or herpes, is a viral infection that causes rhinotracheitis (inflammation of the nasal cavity and trachea), with the classic clinical sign being sneezing. This virus is the “FVR” part of the FVRCP combo vaccine for cats (FVR = feline viral rhinotracheitis). In addition to sneezing and other upper respiratory problems ranging from moderate to severe, “the herp” is also more likely to trigger ocular involvement than other URI pathogens. In fact, feline herpesvirus-1 is the most common cause of infectious conjunctivitis and corneal problems in cats.
What makes herpesvirus-1 so frightening is its potential to enter a carrier state even after the initial upper respiratory infection seems to clear. 80% of affected cats develop a latent infection, in which the virus hides out in the body; the infected cat may appear seemingly healthy at this time without upper respiratory signs. However, during a latency period, infected cats (even if they are currently asymptomatic) act as carriers and can still shed the virus in their environment, posing a risk of transmission to other cats. And of these cats that develop a latent infection, 45% go on to have virus recrudescence (i.e. the dormant virus jumps out from behind its hiding place and goes on to trigger a full-fledged URI and eye problems). These flare-ups often occur during periods of stress (such as acquiring another infection or disease, injury, or household stressors). This latent infection and potential of viral recrudescence may persist for years or even the remainder of the cat’s lifetime.
And before you worry, the answer is no… this herpesvirus strain is unique to cats and is not the same as the herpes forms that are contagious to humans.
Feline calicivirus (FCV)
Calicivirus is included as the “C” in the FVRCP combo vaccine for cats. What vet doesn’t shudder at the thought of feline calicivirus?! This viral infection is considered by many veterinary professionals to be the most severe respiratory disease of cats. Calicivirus is extremely hard to kill; many disinfectants are not effective against it, and it may survive up to 1 week at room temperature. It can also be difficult to treat once a cat becomes infected.
In addition to the classic “head cold” signs, this virus is more likely to cause painful oral ulcerations and vesicles. Some strains are highly virulent, meaning they are extremely dangerous to felines. Severe cases may result in pneumonia or a viral systemic infection that leads to dangerously high fever, swelling (edema) of the face and legs, focal areas of skin crusting with hair loss, and potential death. Outbreaks in animal shelters over the past few years have resulted in death of hundreds of cats.
Like herpesvirus-1, calicivirus can also enter a carrier state, hiding out in the tonsils and oropharynx (back of the throat) in a latency period until periods of stress trigger the virus to cause an upper respiratory infection once again.
Bordetella bronchiseptica (kennel cough)
Bordetella bronchiseptica is the same pathogen which causes kennel cough in dogs. This bacteria affects dogs much more frequently and more severely than it does cats, so canine vaccination is much more common than is feline. However, Bordetella may cause a URI in some cats, primarily causing laryngitis and pharyngitis (inflammation of the larynx and pharynx, respectively). Though uncommon, feline kennel cough may progress to bronchopneumonia in some cases. Fortunately, however, kennel cough is quite easily treated with antibiotics.
Chlamydophila felis
Chlamydophila felis (previously called Chlamydia felis) is a bacteria that primarily causes conjunctivitis in cats, which may lead to conjunctival follicle or pseudomembrane development in some cases. This bacterial organism, unrelated to the STD form in humans, can also lead to a carrier state, causing recurrent eye infections. It also has zoonotic potential; though rare, transmission to humans can occur, most commonly causing eye infection (conjunctivitis) with the possibility of a mild respiratory infection. (Protect yourself by always washing your hands after handling your pets!) Inoculation against Chlamydophila felis is typically performed by cross-protection upon vaccination with Chlamydia psitacci, a related bacteria of birds that will also protect cats against C. felis.
Mycoplasma spp.
Mycoplasmosis is an infection caused by the bacteria Mycoplasma felis or M. gatae. [These organisms cause upper respiratory infections, and are not to be confused with hemotropic Mycoplasma species which cause hemolytic anemia (destruction of red blood cells) and chronic anemia in cats.]
URIs caused by Mycoplasma are not typically as severe as those caused by viruses. Mycoplasmosis is also not as highly contagious as other respiratory pathogens, and some cats exposed to these bacteria may not develop infection at all.
Diagnosis
When you schedule a vet appointment for your cat, make sure to inform your veterinary staff ahead of time that your cat is displaying signs suggestive of an upper respiratory infection. Since the pathogens which cause URIs are often highly contagious amongst felines, your vet will want to reduce the chance of disease spread to other cats in the hospital. You may be asked to wait with your kitty in your vehicle right until your appointment time rather than sitting in the clinic waiting room, or you may be asked to enter a separate entrance of the veterinary hospital, such as directly into a special exam room or isolation ward. Isolation wards follow strict biosecurity protocols that attempt to limit the possibility of infectious disease transmission as much as possible. Don’t be surprised if your veterinarian and veterinary nurse wear special gear (such as a disposable gown, gloves, and booties) when they examine your cat; this is an important biosecurity procedure for the safety of other cats on the premises.
An upper respiratory infection is diagnosed via combination of the following:
- Clinical signs: Sneezing with nasal and ocular discharge is pretty much a tell-tale sign that your cat has a URI. Further tests may be performed to narrow down what the exact pathogenic agent is causing the infection.
- Physical examination: Upon physical exam, your veterinarian may notice that your cat has a fever and is dehydrated (caused by either high fever or due to your cat not drinking because of painful mouth sores). Your vet will also discover oral ulcers, if any have developed, as well as ocular infection.
- Diagnostic tests of the eye
- Staining for corneal ulcers: Your vet may use a special stain, called Rose Bengal stain, to detect any dendritic corneal ulcers (i.e. those caused by feline herpesvirus-1).
- Conjunctival/corneal scraping: The surface of the eye (numbed by topical anesthetic) may be gently dabbed with a sterile swab to gather viral or bacterial particles (such as herpesvirus, Chlamydophila, or Mycoplasma). Further specialized tests (such as PCR, IFA, or bacterial culture) may be performed to identify the exact pathogenic culprit(s).
- Nasal swab: Your cat’s nasal cavity may be gently swabbed for specimen collection. Specialized tests may be performed to identify viral inclusions or perform bacterial culture.
- Blood tests: Though not often needed, serology may be performed to measure high antibodies (a response of the immune system to infection) against a specific URI pathogen.
- Thoracic radiographs (chest X-rays) if pneumonia is suspected
Treatment
In the majority of cases, an exact diagnosis of the precise pathogenic cause of feline upper respiratory complex is not necessary as most URIs are managed via the same treatment protocol.
- Re-hydration: Subcutaneous (SQ) fluids may be administered if your cat is dehydrated. Fluid therapy will also help reduce your cat’s fever. In severe cases, hospitalization with IV fluids may be required.
- Systemic antibiotics: Oral antibiotics will likely be prescribed for 7-10 days in order to prevent secondary bacterial infections or to treat primary bacterial causes of URI (i.e. Bordetella, Chlamydophila, or Mycoplasma). GI side effects (particularly diarrhea) may occur.
Systemic antivirals
- Antibiotics are not effective against viruses. Most viral infections lack a true curative treatment and must simply run their course while supplementary therapies to support the body’s immune system and other side effects may be administered. However, some antiviral medications, such as oral lysine, may be helpful to reduce viral replication in some patients.
- Lysine works by preventing viruses from using the important amino acid arginine, thus decreasing their virulence. Lysine is safe yet is of questionable efficacy. It may help some patients, so it may be worth a try for your kitty.
- Systemic immunomodulator: Oral interferon may be used in severe cases to boost your cat’s immune system to help fight infection.
- Eye care: Topical antibiotics and or topical antiviral (such as cidofovir) may be prescribed by your vet to instill directly into your cat’s eyes. Never administer ocular steroids if your cat has a URI! Steroids can worsen an eye infection and an infectious corneal ulcer. Your cat may need an E-collar to prevent rubbing/scratching a sore eye until a corneal ulcer is healed. Severe and deep corneal ulcers may require surgical therapy.
Nasal flush: Your vet may administer a flush of sterile saline or a liquid medication into your cat’s nasal passages to clear debris. At home, you may be directed to apply a few drops of sterile saline to your cat’s nostrils periodically to keep them moist and prevent nasal discharge from drying and blocking the nasal passage.- Nebulization and/or Vaporization: Nebulization converts liquid medications into a mist form for quicker delivery directly into the respiratory tract; your vet may use a nebulizer in-hospital. Otherwise, your vet may recommend that you place a steam vaporizer or humidifier (with water only) near your cat at home.
- Nasal decongestants: Your vet may prescribe a nasal decongestant, such as a human pediatric formula of neosynephrine. However, it can dry out nasal passages, so it should be used sparingly.
- Nutrition: An appetite stimulant may be prescribed if your cat is hesitant to eat. Because your kitty’s nose is clogged up with nasal discharge and inflammation, he may not be interested in his food because he can’t smell it. Either warm up your cat’s wet food to intensify its odor or opt for a smelly cat food temporarily in order to help a stuffed-up cat smell her food better, enticing her to eat.
If you have more than one cat in your household, pay special attention to how your other kitties are acting. Your vet may recommend bringing all them for examination to ensure that they are not also developing a URI. To help prevent spread of infection in your home, thoroughly disinfect your sick cat’s bedding and any surfaces, food and water bowls, or other items your cat may have contacted.
Prevention
In addition to optimizing your cat’s health overall as well as reducing your cat’s stress (which includes environmental enrichment), the key to preventing urinary tract infections is vaccinating your cat.
Vaccination
Even if your cat is indoor-only and never ventures outdoors, he or she may still be at risk of URI pathogens. Infected outdoor cats shed viral particles , and we humans may contact them on a stroll through our neighborhoods or city sidewalks, tracking them in on our shoes and hands to introduce to our at-risk indoor kitties waiting for us at home. Therefore, vaccination against URI viruses is strongly recommended even for indoor-only cats.
As feline herpesvirus-1 and calicivirus are the most virulent pathogens that cause a URI (i.e. they’re the most likely to be highly contagious and cause worse disease), vaccinations against these agents are called core (or highly recommended). These vaccines are very good at preventing infections before they occur, yet they are not as effective at eliminating carrier states in cats who have been previously infected with these viruses. Because Bordetella, Chlamydophila, and Mycoplasma are not as contagious and do not cause as severe disease, vaccination against them are considered non-core (or optional) and are often reserved only for at-risk cats.
Kittens should be vaccinated against herpesvirus-1 and calicivirus every 3-4 weeks starting between 6-8 weeks of age until they are around 12-15 weeks old. Thereafter, cats should be vaccinated 1 year following the completion of their kitten vaccine series, and then every 1-3 years for the remainder of their lifetime. High-risk cats should receive a vaccine booster annually while low-risk felines should be re-vaccinated every 3 years following their first annual booster. Vaccination against these viruses are often included in a combo vaccine (FVRCP) with feline panleukopenia, given at the same schedule.
If your vet finds your cat at increased risk for either Bordetella, Chlamydophila, and/or Mycoplasma infection, inoculation may also be recommended. Initially, a series of 2 vaccines separated by 3-4 weeks is given; the vaccine is then boostered annually as long as your cat remains at increased risk of these bacterial infections.
Click here to find out more about the recommended vaccines for cats. More of a dog person? Click here.
While some cats may still acquire an upper respiratory tract infection despite being up-to-date on vaccinations, these vaccines minimize the severity of clinical signs and shorten the course of illness should an infection develop. In the majority of cats, however, immunization greatly reduces the likelihood that your cat will develop a URI at all and spread this infection to other felines. Consult with your local veterinarian about your cat’s vaccination status.
– Maranda Elswick, DVM
If you observe the aforementioned signs consistent with a feline upper respiratory infection, seek veterinary assistance. And if your cat is not up-to-date on his or her vaccinations that can help prevent a URI, schedule an appointment with your vet today.
