Cat flu and panleukopenia
Feline herpesvirus, calicivirus and parvovirus: the "core" infections that vaccination is designed to prevent.
Key points. Herpesvirus and calicivirus cause most cat flu. Both are common, and many recovered cats stay carriers. Panleukopenia is rarer thanks to vaccination, but is highly contagious, extremely hardy and often fatal in unvaccinated kittens. All three are covered by core vaccines.
Cat flu: overview
"Cat flu" means upper respiratory infection: sneezing, runny eyes and nose, mouth or eye inflammation, and loss of appetite. Roughly 90 percent of cases involve feline herpesvirus (FHV-1), feline calicivirus (FCV), or both, often complicated by secondary bacteria (International Cat Care). It is most severe in kittens and is common wherever cats live in groups. Treatment is mostly supportive: keeping the cat eating and drinking, cleaning eyes and nose, steam or saline nebulisation, and antibiotics only if a secondary bacterial infection is suspected.
A cat that is not eating (a blocked nose can remove the sense of smell) for 24 hours, or that breathes with its mouth open, needs a vet promptly.
Feline herpesvirus (FHV-1)
What it is and how it spreads
FHV-1 is spread through eye, nose and mouth secretions of acutely infected cats and of carriers whose virus has reactivated. It survives only briefly in the environment, so close contact is the main route, although contaminated surroundings matter mainly in crowded catteries. After the first infection almost all cats become lifelong carriers. The virus lies dormant in nerve cells and may reactivate with stress, steroid medicines, nursing kittens or moving home, causing mild signs or none.
Signs and diagnosis
Sneezing, fever, salivation, nasal and eye discharge, conjunctivitis, and in many cats eye ulcers (so-called dendritic ulcers are characteristic). Chronic or recurring eye and nasal problems can follow. Vets usually diagnose from signs, and swabs can confirm if needed.
Treatment, prognosis and care
- Supportive care, with antibiotics only where bacterial infection is suspected. For eye disease, antiviral eye drops (for example trifluridine) and oral famciclovir may be used.
- The ABCD does not recommend L-lysine because there is no evidence that it works.
- Most cats recover, but flare-ups can recur lifelong. Keeping stress low reduces reactivation.
- Vaccination reduces disease severity and shedding but does not fully prevent infection.
Other animals and people
FHV-1 infects cats and some wild cat species. There is no evidence that it infects people, and although it is related to canine herpesvirus, no spread between species is known (ABCD).
Feline calicivirus (FCV)
What it is and how it spreads
FCV spreads by direct contact with oral and nasal secretions, and indirectly through shared items, hands and even flea droppings. It can survive on dry surfaces for up to a month at room temperature. Many cats shed virus for at least 30 days after recovery and some for years or for life. FCV also changes rapidly, so no vaccine covers every strain.
Signs and diagnosis
- Typical: ulcers on the tongue and in the mouth, sneezing, nasal discharge, fever, drooling and poor appetite, mostly in kittens (incubation 2 to 10 days).
- Pneumonia in very young kittens; transient "limping syndrome" that usually resolves within a day or two; an association with chronic gum and mouth inflammation (the exact cause is uncertain).
- Virulent systemic FCV: a rare, severe form seen in outbreaks in shelters and clinics, with swelling of the face and limbs, skin ulcers and jaundice. Mortality is roughly 30 to 70 percent. This is an emergency.
Treatment, prognosis and care
- Most cats need only supportive care: warm, strongly flavoured food, fluids, nasal cleaning, pain relief. A feeding tube may be needed if a cat has not eaten for more than three days. No antiviral is approved specifically for FCV.
- Most cats recover. Cats that have recovered should still be vaccinated.
- In multi-cat settings, hands, bowls and bedding all carry the virus, so hygiene matters.
Other animals and people
Humans are not susceptible to FCV (ABCD).
Feline panleukopenia (feline parvovirus, "feline distemper")
What it is and how it spreads
FPV attacks fast-dividing cells, including those of the bone marrow and gut lining, which causes vomiting, diarrhoea, dehydration, a collapse in white blood cell count and often death, especially in unvaccinated kittens. Infection of a pregnant queen can damage the unborn kittens' cerebellum, producing wobbly, uncoordinated kittens (cerebellar hypoplasia).
It is spread by the faecal-oral route; infected cats shed very large amounts of virus. The virus is extremely resistant: it can persist in the environment for months or longer and survives freezing. Contaminated cages, bowls, litter trays, shoes and clothing can carry it, so indoor-only cats are not completely safe. Many common disinfectants fail; products containing sodium hypochlorite (bleach), peracetic acid, formaldehyde or sodium hydroxide can inactivate it (ABCD).
Signs and diagnosis
Fever, lethargy, loss of appetite, vomiting, diarrhoea (sometimes bloody) and dehydration. A vet may check white blood cell counts and run an in-clinic faecal test and/or PCR. A negative quick test does not always rule the disease out.
Treatment and prognosis
Treatment is hospital-based and supportive: intravenous fluids, anti-sickness medicines, nutritional support and antibiotics to protect against gut bacteria entering the blood. Survival depends on how early treatment begins and on the cat's age; mortality is high in young unvaccinated kittens. Survivors usually develop lasting immunity.
Prevention and other animals
- FPV vaccination is highly effective and is core for every cat. See vaccination.
- Keep unvaccinated kittens away from unknown cats, shelters and contaminated places until their vaccine course is complete.
- After a case, disinfect thoroughly and delay introducing unvaccinated kittens.
- No human infection has been reported. Dogs can be infected by FPV without becoming ill, and some canine parvovirus variants can cause panleukopenia in cats (ABCD).
When to call a vet urgently: breathing difficulty, collapse, a cat that is straining to pass urine or producing none, repeated vomiting, not eating for 24 hours or more, or sudden weakness in the back legs. See signs that need a vet urgently.
FIV/FeLV-positive cats
Because they may cope less well with infections, these cats should have their vaccinations kept up to date as advised by your vet (see vaccination of immunocompromised cats), be kept indoors, and have signs of cat flu treated early rather than watched. Cat flu viruses and parvovirus are carried by otherwise healthy cats, so an FIV-positive cat is not the cause of such outbreaks in a household.
Sources
- ABCD: Feline herpesvirus infection guidelines
- ABCD: Feline calicivirus infection guidelines
- ABCD: Feline panleukopenia guidelines
- Cornell Feline Health Center: Feline Panleukopenia Virus
- International Cat Care: Cat flu (upper respiratory infection)
- International Cat Care: Feline herpesvirus (FHV)
- International Cat Care: Feline calicivirus (FCV)
- International Cat Care: Feline infectious enteritis (feline parvovirus, panleukopenia virus)