we are in a similar situation with Ernie our aged Catahoula. He is about 14 now and has lived a life "on the edge" as is the habit of this breed. His favorite foods have been thoise he could chase down and kill, so hes been afflicted with many bites and gashes from groundhogs that have protested being on his menu.
In the last two months he had run out of the pasture (Id never seen him run that fast in several years) and he started chasing an AMISH buggy. The horse go annoyed and kicked him so hard he flew.
Both sides of his jaw were busted and the breaks were LENGTHWISE and at the mel flange his whole jaw segtment just hung down. Several hours of surgery and almost a month of recoup and hes still not fully able to use his mouth. Weve hadda switch him to soft food and NO COOKIES (he would recite the Gettysburg Address in drag for a cookie).
Hes got that '"Sorry boss" look all the time and he seems depressed . We are trying to have him hang out with the border collie more and she is also pitching in to jack up his spirits.
We have had a bit of a premonition that he wont be around into the next spring and summer.
We choose to live with creatures whose lives are briefer than ours , and we invest as much love and patience as we would on our own kids. I guess Id have it no other way, but theres always the heartbreak when they leave us.