FIP is a type of deadly viral infection; it stands for Feline Infectious Peritonitis. This disease can cause a wide array of symptoms, and there are 2 recognized "forms" of it. The 2 forms are "wet" and "dry" FIP. The wet form is far more common, and results in fluid to build up in the abdomen (causing a pot-bellied appearance) and sometimes in the lungs as well, causing respiratory difficulties. The dry form of FIP accounts for 1/4 of cases, and sometimes can start out affecting the eye only, but will eventually progress to vital organs such as the liver, kidneys, and brain.
The biggest 2 problems with FIP are...it can be VERY tricky to diagnose, and there is no cure. The reason it is so hard to diagnose is because there is no single blood test that can provide a diagnosis. The only blood test available checks for coronavirus exposure. FIP is one type of many coronaviruses. A positive test indicates exposure to a coronavirus. Many healthy cats test positive on this test, who do not have FIP. Therefore, SEVERAL factors come into play when making an FIP diagnosis, some of which include (positive coronavirus test, low white blood cell numbers, elevated globulin proteins in the blood, elevated liver values, and clinical symptoms).
So, in summary, if your kitty comes back with a positive on the test, there must also be some other factors including blood proteins and lymphocyte counts to support an FIP diagnosis.
However, if the test comes back negative, it is HIGHLY unlikely to be FIP.
There are several reasons why your kitty may be experiencing this eye issue. It is good that he saw the eye specialist, because they are going to be the most experienced in making diagnoses of eye conditions. However, the whole body system needs to be taken into account.
The fact that Bruce is feeling better and has put weight back on is certainly a good sign. I sincerely ***** ***** turns out to not be FIP, and to be something easily treatable.
Here is a good summary to read up on, if it turns out to be FIP:
And this diagram demonstrates the diagnostic process and how complicated it can be:
I hope this has helped. Do you have any other questions for me at this time?