My cat sneezes a lot: cat flu and other causes
The odd sneeze means nothing. Sneezing fits, a runny nose, watery eyes and a cat that stops eating are another matter. Most cases are so-called cat flu, but not all, and in cats a blocked nose has a consequence you do not see in people: they stop eating.
Cat flu: highly contagious viruses
Feline upper respiratory tract disease, what many people call cat flu, is caused mainly by two viruses: feline herpesvirus type 1 (FHV-1) and feline calicivirus (FCV). Bacteria such as Chlamydia felis, Bordetella or Mycoplasma often join in. They spread through direct contact, sneezes at close range and shared objects, and are very common in kittens, shelters, colonies and catteries. Typical symptoms are sneezing, a clear nasal discharge that can turn yellow or green, watery or gunky eyes, fever, lethargy and poor appetite. Calicivirus can also cause ulcers on the tongue and palate, drooling and, in some cases, lameness.
Why it keeps coming back
Almost every cat that gets herpesvirus keeps the virus latent for life, hidden in the nerves. At times of stress, such as a house move, a vet visit, an illness or the arrival of another cat, it can reactivate and cause a new bout of sneezing or watery eyes, and become contagious again. With calicivirus, some cats become carriers that shed the virus for months or years, sometimes without symptoms. That is why it is so common for a cat adopted from a rescue to have flare-ups of cat flu now and then even when well looked after. It is not your fault: it is the nature of these viruses.
Other causes of sneezing
It is not all cat flu. A violent, sudden sneeze with the cat rubbing their face may be caused by a foreign body, such as a blade of grass or a grass seed in the nose. In young cats, nasopharyngeal polyps cause snoring, sneezing and persistent noisy breathing. Dental disease, such as an abscess at the root of a canine or a molar, can open into the nose and cause discharge from one side only. In older cats, discharge from just one nostril, with blood or with deformity of the face, means a nasal tumour must be ruled out. Fungi such as Cryptococcus, irritants such as smoke, air fresheners or dust from some litters, and the chronic rhinitis left after repeated infections can also cause sneezing.
A blocked nose takes away their appetite
A cat decides whether something is food mainly by smell. With a congested nose they cannot smell, and a cat that cannot smell its food often stops eating, which in this species is dangerous because of the risk of hepatic lipidosis. To help, offer very aromatic wet food, warmed to body temperature, in small amounts several times a day. Clean discharge from the nose and eyes with gauze moistened with saline, one piece for each side. Taking them into the bathroom while you have a hot shower, so they breathe the steam for a few minutes, helps clear things. And if they have gone a day without eating anything, see the vet even if the sneezing seems mild.
When to see the vet
An adult cat that sneezes for a few days but eats, drinks and is bright can be monitored. See the vet if they are not eating or eating very little, if they are flat or feverish, if the discharge is thick, yellow, green or bloody, if the eyes are very swollen or shut, if the discharge comes from one side only, if it happens often or lasts more than ten days, or if it is a young kitten, an older cat or one with FeLV or FIV. And it is an emergency if they breathe with the mouth open or with effort, because a cat that cannot breathe through the nose and opens the mouth is in real respiratory difficulty.
What the vet will do
In a typical case of cat flu: an examination, temperature, a check of the mouth for ulcers and of the eyes, and supportive treatment: control of fever and pain with veterinary medication, and an antibiotic if a secondary bacterial infection is suspected. In some cases of herpes affecting the eyes, specific antivirals are used. If episodes are chronic or unusual, tests are considered such as PCR on a swab from the conjunctiva or throat, blood tests including FeLV and FIV testing, dental or skull X-rays, rhinoscopy or a CT scan. As a guide in Spain: consultation 40 to 60 €; respiratory PCR 60 to 120 €; rhinoscopy or CT under anaesthetic 300 to 900 €.
What not to give them
No human cold and flu remedies, decongestants or fever reducers: paracetamol is deadly to cats, and many cold remedies contain it. No nasal drops with decongestants or vasoconstrictors made for people either. Lysine, which was recommended for feline herpes for years, has not shown efficacy in studies and recent reviews no longer recommend it. Essential oils and steam inhalations with eucalyptus or menthol are not safe for cats: many oils are toxic to them. What works at home is the simple stuff: steam, cleaning with saline, tempting food and peace and quiet.
The vaccine: it does not prevent everything, but it helps a lot
The trivalent vaccine against panleukopenia, herpesvirus and calicivirus is one of the core cat vaccines according to the WSAVA and ABCD guidelines. Against the respiratory viruses it does not fully prevent infection, but it greatly reduces the severity of symptoms. Kittens are vaccinated from eight or nine weeks with several doses up to sixteen weeks or later, with a booster at a year and then according to each cat's risk. An indoor cat that never goes out can still catch it from a clinic visit, a cattery stay or a new cat at home. Michipedia's vaccination tool has the full schedule.
In multi-cat homes
If one of your cats has active cat flu, separate them from the others while it lasts, with their own food bowl, water bowl and litter tray, and wash your hands after handling them. These viruses survive for a while on objects and surfaces; calicivirus is particularly hardy and ordinary disinfectants do not always kill it, so wash bowls and blankets often and ask your vet about an effective disinfectant. Before bringing in a new cat, quarantine them for a couple of weeks and have a vet check. And reduce stress for carrier cats: less stress, fewer reactivations.
Most frequent sneezing in cats is cat flu caused by herpesvirus or calicivirus, which can stay latent and reactivate with stress. Steam, cleaning with saline and warmed food help, but if they stop eating, the discharge is one-sided or bloody, or they breathe with the mouth open, go to the vet.
Educational content from Michipedia, translated from the Spanish original. It does not replace the advice of a vet or a feline behaviour specialist. Every cat is an individual.