My 1yo cat has just been diagnosed with IMHA. Her red blood cell count was 10 (should be between 30-50) so she is quite unwell; we've known this for a while though, she's been lethargic, very pale gums, very thin despite eating well.
I'm speaking to the vet tomorrow re treatment (antibiotics and steroids) but the internet isn't turning up much in the way of people who have experienced this with youngish cats (loads on dogs, for which IMHA is very much more serious apparently).
Does anyone else have any experience of this? Am feeling unsure of the long term prognosis and very sorry for her 
she came from a litter with her sister who is bouncy and healthy by comparison.