Neurological and ocular FIP

What is FIP? – FIP is caused by a common and a largely innocuous enteric coronavirus, like those causing colds in humans and diarrhea in foals, calves and poultry. Most cats are infected with the feline enteric coronavirus (FECV) at about 9 weeks of age and may be reinfected several times before reaching 3 years of age. FECV infections, like those of any other infections of cats, become less common after this time. In about 10% of cats, mainly kittens, the enteric coronavirus will undergo specific mutations that allow it to escape the cells lining the lower intestine and infect the most basic cell of the immune system, the macrophage. This macrophage infection is eliminated in all but 0.3-1.4% of cats, which for unknown reasons are unable to develop the required protective immunity. However, in some cases the infected macrophages leave the intestinal lymphoid tissues and migrate in the bloodstream to distant sites including small veins in the linings of the peritoneal cavity, the uveal tract of the eye, the ependyma and meninges of the brain and spine. The disease that occurs in about 1% of of cats can clinically manifest within days, several weeks, sometimes months, and rarely a year or more. The form of disease that is manifested is referred to simply as wet (effusive) or dry (non-effusive). These two forms are easily distinguishable, although there may also be transition forms between the two. Some cats may present with signs of dry FIP but later develop wet FIP, or vice versa. Overall, about one-half of cats will present with wet FIP and one-half with dry FIP. Less than 5% of diseased cats, usually those with milder forms of dry FIP to start, will survive longer than one year, even with the best symptomatic care.

FIP manifestations and forms

Clinical manifestations of FIP- The clinical manifestations of wet (Table 1) and dry (Table 2) FIP vary according to the site(s) of in the body where infected macrophages end up and cause inflammation. The intensity and character of the inflammation is responsible for the disease form. Wet FIP is the more acute and severe form of FIP and is characterized by accumulation of inflammatory fluid either in the abdominal cavity and/or chest cavity. Involvement of the central nervous system (CNS) and eyes is relatively uncommon in the wet form of FIP (Table 1). The dry form of FIP is characterized, not by diffuse inflammation and fluid effusion, but rather by less numerous and more tumor-like lesions (i.e., granulomas) in organs (e. g., kidney, cecum, colon, liver, lung, lymph nodes) within the abdominal or thoracic cavities, or in the eyes and brain (Table 2). Whereas the brain and/or eyes are only involved in 9% of the wet cases, neurological and-or ocular disease is seen as the main presenting clinical sign in 70% of cats with dry FIP.

Continue reading here…