Hello,
First of all, I'm so sorry to hear about your cat's diagnosis, it is absolutely devastating, and I hope you're coping.
My beautiful boy Tomas was diagnosed with FELV (leukemia) in September 2016 after a lot of tests. He first took ill in October 2015 (was lethargic and not eating). The vet found that his blood cell count was very low (is supposed to be around 48 I think, but his was 8) and he was tested for FIV and FELV but both came back negative. He was put on steroids, and luckily he appeared to make a full recovery - he was back to his old self in days and regular blood tests showed his cell count rising. So he came off the steroids gradually a couple of months later.
A few months after that, the same thing happened - so the treatment was repeated. He was healthy in himself, racing round, eating well etc. The vet said we should run the FIV and FELV tests again and send to a specialist lab as it can be hard to detect. Tragically it came back positive for FELV. The vet said that as he was responding well to the steroids and living a normal, happy life, he could stay on them - though he did explain that his lifespan would be very short.
After interrogating the vet some more we made the decision at that point to continue treating him, and to spoil him rotten, and that when the time came we would do the right thing for him. We had another wonderful 11 months with him, before he went into the first stages of organ failure and slowed down. At this point we had him PTS. It was devastating but we all (my family and I) know that we gave him the best life possible, and that he was a very happy cat.
Tomas was five when he passed, and I'd adopted him when he was one, and I was living in Spain. He was tested by his rescue centre, had blood tests before he could emigrate to the UK, and was always immunised. We have no idea where or how he got it. I'm just grateful that I was able to give him a wonderful - if too short - a life after a tricky start.
If you want to chat privately about it, please let me know. I'm happy to offer more insight / support. xx