FIP is a mutation of the feline coronavirus. Many cats carry this virus but only in a small proportion does it actually mutate into FIP.
There are different types of FIP. Namely:
- Wet FIP. In this, the cat develops fluid in his or her abdomen and/or chest area
- Dry FIP. In this, the cat develops inflammation in his or her body. The inflammation can develop in different organs
- Ocular FIP. This is a variant of dry FIP in which the eyes are affected and there is inflammation in the eye
- Neurological FIP. This is also a variant of dry FIP where the cat has inflammation in the nervous system
The diagnosis of FIP is often difficult to make. With wet FIP, the distended abdomen is often visible and thus a lot easier to diagnose. Dry FIP, on the other hand, is a lot more difficult.
When a cat is already a carrier of the virus, FIP can often mutate after a stressful situation. So, in Nacho's case, spaying.
FIP occurs mainly in young cats up to 2 years of age or just in older cats. It is said that purebred cats are more likely to develop FIP but this has not been scientifically proven. Basically, any cat could get FIP.