Confusion on FIA? Advice needed.

I've taken my 7 month old domestic longhair cat to the vet 4 or 5 times now. At first the vet thought he just had allergies. Now she suspects he has FIA. She said there are two types of this anemia that show almost the exact same symptoms. She said one is treatable with 21 days of doxycycline, the other isn't treatable and is fatal. I can't remember what the vet said the specific names of the two types were. One sounded like it had 'Barton' toward the end of the name. I don't know anything about either type of condition. The vet did say that she would guess he has the treatable type; she said usually with the fatal type, the cats are already on death's door by this point. So I'm hoping and praying she is correct. I don't know if I could bear to watch my little baby die so young. She gave me the doxycycline to get him started on since she's guessing it's the treatable kind and said I should know which way it will go by Wednesday or Thursday. The treatment should either have him showing improvement by then if it's the treatable kind she said. Does anyone know the two types she is talking about?

The vet did do a blood test and she said his red blood cells were a little low. His temperature was 103.5°F. He has been breathing rapidly for 2-3 weeks now, maybe more, which is why she first thought he had allergies and had been treating him for allergies (allergy shots and allergy medication). He is sneezy. His third eyelids have been showing for 5 days. He still seems to have energy. He plays with out other cat and his toys. (The vet said I don't need to separate the two cats). He eats treats and wet cat food. He hasn't been eating much of his dry food that we leave out though. We have been battling fleas for months, but have finally got that under control, I believe. He has had lots of gas, been burping, and licking his lips a lot.

Could anyone offer any advice? If anyone has dealt with this, does this sound like the treatable kind? Can you offer any words of hope? I'm really worried and very anxious about my little boy. Also, to those that pray, would you please say a prayer that he gets well?

It sounds like your vet is talking about the two forms of Immune Mediated Hemolytic Anemia: http://www.veterinarypartner.com/Content.plx?A=1390

Two possible causes are haemobartonellosis and feline leukemia.  Other autoimmune disorders can occasionally be involved.

Have they done any other types of blood tests?  Does your vet know about the digestive issues?  Licking the lips can be a sign of nausea, and there are medications that can help with that.

The vet did another blood test to check for feline leukemia and feline aids. Both were negative. She is aware of the digestive issues. Haemobartonella was one of the types she mentioned. Something-cytox was the fatal one whe mentioned but she said since he's been feeling with this for a few weeks now and hasn't died, it's probably not that one. She thinks he has haemobartonella and sent off another blood test to confirm it's haemobartonella. He still has a fever of 104 (up from the 103.5 last time) so she put him on azythroicin and prednisone in addition to the doxycycline to try to get the healing process going.