Cat flu

Cat flu is one of the most common diseases in cats and can be extremely frustrating for both owners and vets. It is normally caused by several pathogens which include both viruses and bacteria.

The common pathogens that cause cat flu are:

Herpes Virus (FHV): this causes recurrent eye and airway problems (rhinitis). Once a cat has caught the disease, it can return during stressful periods such as boarding in a cattery. It is similar to cold sores recurring in infected people.

Calicivirus (FCV): This can also affect the nasal passage but less seriously than FHV. It can cause mouth ulceration and sometimes chronic mouth inflammation (gingivostomatitis) throught a cat's life .

Bordetella Bronchiseptica: This is a bacteria which both dogs and cats can catch. It normally causes respiratory signs (tracheobronchitis) and is very infectious spreading from one animal to another. It is related to the bacteria that causes whooping cough in humans.

Other bacteria include Chlamydophila felis, Mycoplasma felis and Bartonella henselae.

Often, infected cats that recover aren't able to completely eliminate the pathogens/organisms from the body and so remain as "carriers" spreading the disease to other cats in the future.
Cat flu pathogens can survive in the environment for several days. The disease is spread by being in contact with infected cats, carrier cats and a contaminated environment.

Common symptoms of cat flu include sneezing, nasal discharge, conjunctivitis (irritated and weepy eyes), inappetance and a fever.

Treatment is frustrating and often symptomatic. Often an oral antibiotic, like doxycycline, is used for the bacterial component of the disease. Eye drops can help with the conjunctivitis e.g. chloramphenicol. Other commonly used drugs may include appetite stimulants (e.g. cyproheptadine) and mucolytics (e.g. bromhexine) to decrease the nasal secretions.

Antiviral drugs, such as interferon and acyclovir, given in a variety of ways (e.g. eye drops, injectable and oral) are used to varying degrees of success but are quite expensive to use.

Lysine can be used long term to stop the replication of the herpes virus which is useful for stopping recurrences.

There are effective vaccines against Bordetella, FHV and FCV. Cats still may develop disease though if they caught a pathogen before vaccination and/or there are many pathogens involved.