Megacolon (not a joke)

My dog was diagnosed with this. Basically she had eaten a toy a long time ago and hasnt been the same since. She gets constipated a lot and recently i guess it was so bad that her colon was stretched out too far and they believe it will permanently effect her motility and the colon muscles will not be the same. Some meds prescribed were lactalose and cisipride to help with that and to keep things soft. Anyone ever heard of this in a dog (more common in cats) as well as a long term outlook? Things are going to get expensive for meds forever....

Edit: the toy was fully removed a long time ago