In the past few weeks there seems to have been an increase in the incidence of cat flu. The disease is highly infectious and can be a great problem where large numbers of cats are held in close proximity.
The disease is caused by two viruses. The feline herpesvirus and feline calicivirus have both been isolated from naturally occurring infections.
Both cause identical symptoms and are usually associated with various bacterial invaders which can complicate the clinical picture after the initial viral attack.
The feline herpesvirus does not survive long in the environment and is quickly destroyed by heat and drying. The calicivirus is more stable and can persist for up to a week in normal conditions.
The most likely method of transmission of the disease from cat to cat is by the inhalation of droplets sneezed by an infected animal or transferred directly from nose to nose by sniffing. The incubation period is from two to six days.
Symptoms vary considerably and depend upon which part of the respiratory tract is most affected. Early symptoms are usually quite mild.
The cat may sneeze or cough occasionally but otherwise behave normally. Soon the sneezing becomes more frequent and quite violent.
The eyes become reddened and begin to weep and the cat becomes quite depressed. The cat is reluctant to eat and may go to its food bowl but appears to lose interest as it is unable to smell the food.
Sometimes the virus attacks the tissues of the mouth and throat rather than the nasal passages and eyes. The cat may begin to dribble, have difficulty in swallowing, and may cough.
Examination of the mouth often reveals large ulcers on the tongue and intense inflammation of the tissues of the throat.
Occasionally a cat is presented which has a suddenly developing intense swelling of the eyelids of one eye. No other symptoms are present and it is not for some days that the other eye becomes affected or the cat begins to sneeze.
All cats are susceptible to these viral infections. An animal that has recovered from a natural infection is not permanently immune. It seems that immunity only lasts four to five months at the most.
Siamese and Burmese cats seem to develop more severe infections than non-pedigree cats.
Young kittens are particularly vulnerable and can develop severe complications very quickly.
Quite a high proportion of cats, although appearing normal in every respect, may act as carriers of the virus. Any stress such as injury, pregnancy, or confinement in a boarding establishment results in the shedding of the live virus.
As the cause of cat flu is viral, treatment does not affect the primary causative organisms.
Antibiotics are usually administered to control secondary bacterial infection which can cause serious complications. If the animal is not eating, fluids and soluble foodstuffs must be given intravenously.