My one dog has always had anal gland troubles. I think that allergies did make the situation worse so once I changed her diet it did help although she still has trouble.
The vet told me that her glands are situated further out and so it is difficult for them to be emptied naturally or manually. So, I don't do that myself. I have also heard that fiber does help - bulks up the stool and helps to clear the glands.
Thank you golfgirl for the tip on freezing the pumpkin - never thought to do that and would keep it fresh for longer. I usually open a big can and keep it in the fridge but I like your idea.