Kittens are most commonly affected. Most cases start with sneezing.
Lack of appetite
Discharges from the eyes and nose
Mouth ulcers (especially with FCV) and gum inflammation
Conjunctivitis, which can be severe
In cases of secondary bacterial infection, there can also be copious, thick and opaque nasal discharge that may block the nose forming a crust. Additionally, ocular discharge may be present, which can prevent the eyes from opening
The two main causes are Feline Herpesvirus (FHV) and Feline Calicivirus (FCV). They are both widespread across the world. They not only affect domestic cats, but also other members of the cat family. Different strains of FCV vary widely in their ability to cause disease, the severity and the symptoms they exhibit. Recently some very virulent strains of FCV have been seen which affect the whole body and may lead to death.
The cat flu viruses are spread very readily in air droplets when a cat sneezes, and also in eye and nasal discharges. This may be either direct from the infected cat, via a person’s clothing, or wherever the cat has rubbed its face. Most cats that recover will become carriers and shed virus after they have stopped showing symptoms. These cats are then a potential source of infection for other cats. FCV virus is shed continuously for a variable time after recovery. On the other hand, cats with FHV remain carriers for life, but shedding is intermittent and generally associated with periods of stress.
Although the viruses are fairly readily killed by disinfectants, they may remain active in discharges for up to a week. They can spread through a colony of cats very rapidly, and are of concern in catteries and rescue centres, where they can be very difficult to eradicate.
Classic cat flu is usually diagnosed on clinical signs, clinical examination and history. A range of laboratory tests on swabs taken from the eye and/or mouth, or tests on blood samples can identify the viruses.
The primary causes of cat flu are viruses, for which no licensed drug treatments are currently available. Treatment is aimed at supporting the cat and treating any secondary bacterial infections.
Fluid therapy if cats are dehydrated
Treatment to control symptoms, such as runny nose and blocked sinuses
Nursing care is critical for good recovery. All discharges should be wiped away gently, the nostrils should be kept clear. The mouth should be kept as clean as possible
Encouraging the cat to eat by offering gently warmed, smelly and palatable food.
Good general supportive environment, e.g., warm and draft-free
Infected cats should be isolated from other susceptible cats and hygiene precautions taken (change of clothing/ disinfectants) to avoid spread of infection.
Most cats will recover fairly well, provided they receive suitable treatment. Many, however, will have some persistent problems such as sneezing, nasal discharge and conjunctivitis. In the case of FHV these signs can reappear at the times of stress, such as taking the cat to the cattery.
Vaccination can help prevent cat flu. The cat flu component is virtually always included in the primary vaccination course, and often in every routine annual booster. Vaccines help to reduce the severity of disease but they do not always prevent infection or prevent cats from becoming carriers.
Your veterinary surgeon will advise you on the most appropriate vaccination schedule for your cat.
An up-to-date vaccination is often obligatory before going to cat shows and many catteries.