My GSD Chloe is an ex rescue...she was dumped in the pound at 6 mths old and was saved by GSD Rescue and we got her at 7.5 mths old...she is now 26 mths old and still naughty but much better than when we first got her. I too had a Rottie but we lost her last year to cancer...she was 10 yrs old and missed every day.
Had she been surrendered to the R$PCA she would have been put to death as she would be deemed unsuitable for re homing...why ? because she's a GSD and playbites...jumps up on people...very hyperactive...chases balls and barks and growls at dolls...their so called temperament tests. This private organisation knows nothing about dogs or dog breeds...how the hell can they justify killing a dog because it barks at a bloody doll.
That's crazy! Glad she is with an awesome family who understands her!
Im sorry to hear about your rottie , poor thing.