flu is a common cat disease that can be life-threatening.
Symptoms include sneezing, nasal discharge, conjunctivitis
(inflammation of the lining of the eyes), discharge from the
eyes, loss of appetite, fever and depression. Occasionally,
mouth and eye ulcers and excessive drooling of saliva may
be seen. The very young, very old and immunosuppressed cats
are more likely to develop severe disease and possibly die
as a result of their flu. Where death occurs this is usually
because of secondary infections (infections with bacteria
in addition to the flu viruses), lack of nutrition and dehydration.
is at risk?
flu is most commonly seen in situations where cats are kept
in large groups such as breeding catteries, rescue centres
and feral cat colonies, although it can also be seen in pet
most at risk include unvaccinated cats, kittens, the elderly
and cats which are immunosuppressed for any reason. In immunosuppressed
cats, damage to the immune system has left them vulnerable
to a wide variety of diseases with which they would otherwise
be able to cope. Immunosuppression can be seen in cats infected
with feline leukaemia virus (FeLV) or feline immunodeficiency
virus (FIV), cats with other severe illnesses, or in those
receiving treatment with certain medications such as corticosteroids
or anti-cancer therapy.
vaccination helps to reduce the risk of cat flu, this disease
can still be seen in vaccinated cats.
symptoms of cat flu are most frequently caused by infection
with one or both of the cat flu viruses - feline herpesvirus
(formerly known as feline rhinotracheitis virus) and feline
herpesvirus (FHV) infection often causes severe and potentially
life-threatening illness. Although the majority of cats infected
make a full recovery, this often takes several weeks and some
cats are left with permanent effects of infection such as
chronic rhinitis. Cats with chronic rhinitis are usually well
in themselves but have a persistent discharge from the nose
and sneeze. Secondary bacterial infection of damaged tissue
can cause chronic conjunctivitis, sinusitis and bronchitis
(inflammation of the linings of the eye, sinuses and air passages).
Antibiotic treatment usually only provides temporary relief
of these symptoms.
calicivirus (FCV) infection usually causes a milder form of
cat flu with less dramatic nasal discharges. Characteristic
mouth ulcers are sometimes the only sign of infection. The
ulcers may be present on the tongue, on the roof of the mouth
or the nose.
strains of FCV cause lameness and fever in young kittens (these
can occasionally be seen after vaccination). Affected cats
recover over a few days although they may need pain killers
through this time. More recently more virulent strains of FCV have been identified in the USA and UK. Among other clinical signs these strains often cause severe swelling of the face and paws, skin ulcerations on the head and limbs, and jaundice (yellow gums and skin). They have deleterious effects on the whole body with a high mortality rate (up to 67%). Further investigations into these strains are currently ongoing.
by the veterinary surgeon is based on symptoms and laboratory
tests. Testing for flu viruses requires taking a mouth or eye swab
which is then sent to a specialised laboratory where the virus
is grown and identified.
there are currently no drugs available to kill these viruses
so treatment is aimed at supporting the cat through its illness.
This treatment includes antibiotics, to treat any secondary
bacterial infections as these can be life-threatening, and
drugs to help loosen the nasal discharge and make breathing
less of a struggle. As cats with flu are often reluctant to
eat, they may need to be tempted by offering gently warmed,
smelly and palatable food. Syringe feeding of liquid food
can be tried if necessary, although caution is advised. Severely
ill cats may require hospitalisation for feeding by a tube
placed down their nose or directly into their stomach.
a compound that interferes with virus replication, has received
a lot of attention recently in the treatment of many viral
infections. Recombinant Feline Omega Interferon is the first
veterinary interferon available on the European market and
has antiviral and immunomodulatory properties. To date there
is little documented evidence for its success in cats for
the treatment of FHV and/or FCV.
is an anti-viral eye drop that is a licensed human product
that has been used with some success in cats with severe eye
lesions as a result of FHV infection.
Fanciclovir and aciclovir,
drugs given in human herpesvirus infections, have also shown some good activity against FHV.
cats may also need fluids given intravenously via a drip.
General nursing is also essential. Discharge around the eyes
and nose should be gently wiped away using a damp piece of
cotton wool and the cat should be kept warm and comfortable.
cats that recover from cat flu become 'carriers'. Carrier
cats usually show no sign of illness themselves but, by shedding
virus in their saliva, tears and nasal secretions, are a source
of infection to other cats. FHV carriers shed virus in their
secretions intermittently. Shedding tends to occur following
times of stress, such as a stay in a boarding cattery, and
may or may not cause some recurrence of flu signs such as
sneezing and nasal discharge in the carrier cat. Treatment
for other diseases using corticosteroids may also precipitate
an episode of virus shedding. Cats that are FHV carriers remain
so for the rest of their life. In contrast, most cats infected
with FCV shed the virus continuously for a short time after
recovering from flu and then virus shedding stops. In a few
cats FCV shedding continues for several years.
flu viruses are spread in three ways.
- Direct contact with an infected cat
showing signs of flu.
- From contact with virus carried on
clothing, food bowls and other objects. Large amounts of
virus are present in the saliva, tears and nasal discharges
of cats with flu. The virus is able to survive in the environment
for up to a week.
- From contact with a cat that is a
carrier of cat flu. Breeding carrier cats are a risk to
their kittens as the stress of kittening may precipitate
shedding of FHV and infection of the kittens with either
FHV or FCV may occur before the kittens are old enough to
risk of developing cat flu can be reduced by regular vaccination
against FHV and FCV. These vaccines stimulate the cat's immune
system helping it to fight infection and protect it from developing
disease. However, although vaccination usually prevents severe
disease developing, they are not always 100% effective against
preventing infection and mild disease may still occur in some
cats. FCV has several different strains and work is still
ongoing to develop more effective vaccines. Recently
some newer vaccines have been marketed, which include cover
against some of these more recently recognised strains.
is advisable to vaccinate all household cats, especially if
the cat goes outdoors, stays in a cattery or goes to cat shows.
If an individual develops cat flu, subsequent stress, such
as attending a cat show, should ideally be avoided.
cats should be vaccinated before they are mated so that they
produce high levels of antibody in their milk. These maternal
antibodies only protect the kittens until they are about 4
- 8 weeks old, after which the levels of antibody gradually
disappear. Kittens can only be vaccinated successfully when
the levels of antibody have disappeared at between 6 and 12
weeks of age.
that recover from infection with FHV or FCV may be able to
resist future infections (be immune) for up to a year or more.
As there are many strains of FCV, a cat that recovers from
infection with one FCV strain can still subsequently be infected
with another. Vaccines use strains of FCV which give the most
cross-protection to other strains, to try to provide as broad
a protection as possible against this infection. This is not
an issue with FHV as only one virus strain exists.
the spread of infection in a multi-cat environment involves
'barrier nursing' of infected cats. The infected cat should
be isolated from the other cats, for example kept in one room
of the house, where it can be treated without the risk of
spread of virus to other cats in the household. Separate food
bowls and litter trays should be used for this cat. These
should be disinfected with a product which kills the virus
but is safe to cats, as recommended by a veterinary surgeon.
In a cattery, one person should look after the ill cat, and
they should disinfect their face and hands and change their
clothes or overalls when leaving the cat in isolation. If
one person cares for all the cats, the infected cat should
be handled last of all the cats in the home.
Updated November 2008