KoolKats: You said they were brothers - but it could be they were just two unrelated cats that were abandoned together. Then Donut would not necessarily have FELV. There is really no way to know they are brothers unless you have a DNA test done, so I wouldn't worry too much about Donut. Concentrate on Sparks.
The treatment Stephen cited may very well be the one your vet is using, although I am not sure about the confusion concerning "surgery" vs. "injection." But either way, don't panic. Just get a second opinion if you can.
The treatment Stephen cited may very well be the one your vet is using, although I am not sure about the confusion concerning "surgery" vs. "injection." But either way, don't panic. Just get a second opinion if you can.