They're running a test on the bone marrow to see if could have FelV in his marrow but not visible in his blood.
We're also waiting on a toxoplasmosis test since he has some minor neurological signs (back legs land a little wrong when he jumps, head shakes a little when he focuses on something).
The good news is, he's not getting any worse, although I suppose that could change quickly. We're keeping him on the doxycycline, just in case he has blood parasites but has had an abnormal reaction to them (non-regenerative instead of regenerative anemia). Also, we're trying to get a fecal sample to test for a gastrointestinal problem - if he cant absorb nutrients that would explain his severe weight loss despite eating, and a lack of B vitamin could explain his non-regenerative anemia. Unfortunately, he has not been cooperative about going while we watch.
Right now he's just resting on my lap. He's still really lethargic but still eating and drinking by himself. His hematocrit went up from 16% 8 days ago to 27% yesterday, so his anemia does seem to be improving, although the Auburn doc said since each test was done in a different lab on a different machine, some variation is expected, and with nonregenerative anemia it's unlikely his improvement is as dramatic as it might seem.
We're still so clueless.. they said it could also be related to his liver - his ALP was a little high which might indicate he's suffering some liver problems, but the rest of his liver enzyme levels are normal. On the ultrasound, everything looked normal except his liver looked a bit bright (possibly caused by the Stanazol our local vet gave him) and his kidneys were a little smaller than normal, but all his kidney blood and urinalysis tests were normal.
So basically, yeah, no clue. I hope he has some kind of intestinal parasite because that sounds like it'd be the easiest to fix, but first we need a stool sample.
Oh, and his albumin and globulin levels are normal, so there's only about a 1% chance he could have FIP, even the dry kind.
Could it be Fia my old Cat had taht and almost died at age 9. They did alot of tests at the Er Vet but my reg Vet found it. Before Coco got it Lucy kept getting sebvere Anemia out of no where and needed Blood Transfusions. She would be normal then real bad and no one knew what ws happenind. then on Aug 20th 2001 She got real bad and died on the way to the Er Vet. Three weeks later Coco got the same way and went to Er and they couldnt figure out why the Anemia was so bad. she almost died and they said to have her pts and get a 2nd opinion. her fur fell out and she was only 4 Pounds at the time. They said maybe Diabetis. Our vet found out it was Fia. I had my other Cats tested and they were fine. Coco is amost 16 now. I hope they find out what your cat has.
We found out he either has a B12 deficiency or a food allergy - so he's on a special diet and gets a B12 shot about once a week. He's doing so much better - his fur is very soft and fluffy and he's plumped out and is perking around.