You may find some helpful tips here, in General Guidelines: http://www.homeovet.net/dynamic/php/downloads/dog-c8470f2c75dbe4b683205c3919ee2310/dog_diet_complete.pdf
and here http://skeptvet.com/Blog/category/nutrition/
Age 7 is considered senior for a dog, it wouldn’t be a bad idea to have a geriatric workup done, lab work etc. See what your vet recommends….. otherwise, one or two feedings per day, long walks, an occasional snack (just a bite), should do the trick.
Adequate elimination, one or two bowel movements a day, are a good thing. Constipation would be more problematic. Also, make sure they are getting enough water, as dogs get older they are more vulnerable to bladder stones.
The best scenario is to offer a bathroom break at least every 4 hours (minimum).
