If untreated mild cases of cat flu can progress to pneumonia due to secondary infections.
The infectious agents that cause cat flu can be identified from a variety of tests including isolation from swabs, and from blood tests (measuring antibodies) in some cases. Unfortunately interpretation of the results can be misleading. For example, some of the viruses that can cause the signs of cat flu may be found in samples taken from healthy, unaffected animals. This means that a cat's immune system probably has to be compromised for it to develop the disease.
In prolonged cases or cases unresponsive to conventional treatment it is wise to screen for the presence of feline leukaemia virus (FeLV) or feline immunodeficiency virus (FIV) as these may compromise immune response making recovery difficult.
There is no specific treatment for the viruses that cause cat flu but symptomatic treatment and care is needed. The exception to this rule is for corneal ulcers caused by feline rhinotracheitis virus, as these can be treated with the antiviral agent trifluoridine - which is applied 8-10 daily to the eye. Providing an infected cat is able to mount a normal immune response to the infection, viral cat flu is a self-limiting disease and most cats recover in 2-3 weeks. A small number of cats become chronic carriers of the infection- particularly if they have concurrent feline leukaemia virus (FeLV) or feline immunodeficiency virus (FIV) infection.
Bacterial infections are treated with antibiotics - usually ampicillin, amoxycillin, tetracyclines or potentiated sulphonamides.
Chlamydia infection is treated with tetracyclines - usually given by injection for a week, as local administration into the eye is less effective.
In all cases the opening to the nose should be kept clean by wiping away collected debris and discharges. Sometimes the use of a nebuliser or decongestants (e.g. pseudoephidrine) is recommended in severe cases.
Long term problems