We have 2 small rabbits who we got as adult rescues in 2006 - not sure of their exact age but at least 11 years old now, the male possibly a little bit older (the rescue had him down around 2 years old back in 2006).
I know that they are unlikely to live an awful lot longer, but they are suddenly both not thriving the way they were until a few months ago - vet says there is nothing wrong specifically, they are just very old, and suggested switching them to junior rabbit food as they have got a bit scrawny over the last few months and weren't bothering much with eating their dry food (though still eagerly eating fruit and vegetables).
They like the junior food a bit better but haven't put the weight back on really.
What do you feed elderly rabbits to keep them in the best condition as long as possible?