My dog has never had to have her anal gland squeezed. Today I came home and found what looked to be poo but lighter in color and mostly liquidly with a little mushy( like apple sauce) texture to it. When I went to clean it up I noticed that it had a foul smell to it. acidic, almost like fish mixed with Orange juice. 
At first I didn't think much of it. She has a sensitive stomach combined with my idiot family who won't stop giving table scraps= runny to loose stool. 
I also noticed a couple of days ago that in the snow where she will normally lay there was some liquid there too....looked like when you spill soda on snow. Didn't think much of it at the time( thought my bros spilled something there.)
Could she need her glands expressed or is she doing them herself some how.
It seems like she is having more problems since she got spayed...no regrets though. oh and by the way she is 8yrs old. Never had this problem before.
Oh and by the way...sorry if I ruined any of the above mentioned foods for ya. I know.....gross.