First, I'd like to thank everyone here for all the wonderful information you so willingly share. I read often, but this is the first time I've posted.
My dog Jack is a 14 year old mutt, very healthy but had to have some teeth out about 6 months ago. After the dental surgery he had to eat soft/canned foods for a couple of weeks and since then I've been giving him a mixture of canned and kibble. Prior to this he always had just kibble (and occasional treats from the kitchen - veggies, meat scraps, cheese, etc). Jack has always been a grazer - he doesn't have set feeding times, just eats throughout the day when he wants to. His weight is great according to the vet and this has always worked well for us.
Recently he had diarrhea for a few days and that got me wondering about leaving the canned food in his dish all day. I've been giving him about 1/2 a can of food mixed with about 1/3 cup of kibble every day. Anything that's not eaten I toss in the morning and put out fresh. If the bowl is empty before the end of the day I give him a little more kibble to get through the evening. The cans say to refrigerate after opening, which I always do, but how long can it be left out at room temp for him to eat before it's not safe?
Jack has been very happy to have the canned foods added to his diet and I'd hate to go back to just kibble, but I don't know that I could get him onto a feeding schedule at this age, or that I really want to. Allowing him to regulate his own food quantities has really worked well; he eats less when he's being lazy, more when he's active and has always been lean and healthy. I could put 1/4 can out in the morning before I leave for work and then another 1/4 can in the evening when I get home, but I don't know if even that is too long to leave it out. Some days he'll gobble up 2/3 the dish before I've even left for work, but other days he doesn't each much of anything until evening and there doesn't seem to be any way to predict when he's going to be hungry.
It's probably not relevant, but he ate Solid Gold Hund'n'Flocken for years, then Solid Gold Holistique, and in the past year we've switched to EVO. I've been giving him a variety of canned foods - California Natural, Innova (including EVO), Wellness, Solid Gold, Prairie, Evanger's, Canidae. A lot of wheat/corn in his food tend to make him lick his feet and chew at his tail, so I've generally avoided grain-heavy foods for most of his life.
You guys seem to know everything there is to know about dog feeding, so I thought maybe someone here would have some ideas.