We had to put Leia down.
Born with a very severe congenital heart problem, her prognosis was grim from the start. We kept her going for a year - she just turned 1 on the 5th - with no pain, but our luck ran out. She threw a clot, cutting off blood supply to her hind legs. I heard her make a funny noise, and went to check on her. When it became apparent she couldn't move her hind end we rushed her to the vet.
She had no pulse in either of her back legs, and without blood the muscle tissue was dying. It's excruciating, and she was quickly given high doses of pain medication and valium. When she calmed down we spent a little time with her. We brought her brother, her littermate, along (they were inseparable) and she seemed comforted by his presence. He kept licking at her hind legs, trying to help her.
Her lungs started to crackle, probably from secondary clots, and after just a few minutes of kisses and petting the vets gave her the final medication.
I like animals, a good deal more than I like people, and loosing one is always devastating for me.
I know, with time, I will feel better. Right now however all I feel is the loss of my sweet sweet little girl.

Greif, as they say, is the price we pay for love.