There is nothing so sad as an abandoned pet, in my opinion.
Here's the story of the first two cats I knew:
Cat no. 1, a little black cat!!!
Who was abandoned, along with her ginger brother, when their owner moved house. Brother was taken in by a lady along the road, black cat moved in with us. She tried the food on offer at all the houses along our road, and chose ours. They both lived to a grand old age.
Cat no. 2, a little tabby cat!!!
Who we assume was abandoned, she was about 8-12 months old when found (vet couldn't be sure), spayed etc. but probably her 'family' got bored with her when she was no longer a kitten, and threw her out like so much rubbish. She lived in our garden for six months & refused to come in. Then she developed cat flu, came in to be nursed, and never left. She lived to be 17-ish.
Both these cats were friendly, polite, loving sweethearts. How their original owners could just discard them like that is beyond me, yet it goes on and on. I applaud Cats Protection for the work they do, thank God someone does it. (The two cats I have at present came from CP). They are one of my favourite charities.