I have 3 adult dogs, one Great Dane, one German Shepherd, and one Rottweiler. After we tried to change them to adult food, they wouldn't eat it. They only ate their old puppy food. We've tried a lot of different brands too, and they won't eat it.
Put it down and do not give them anything else. They will not starve themselves, they will eat it when they get hungry enough. It's time to practice a little tough love.
Make sure you're feeding a high quality brand of dog food.
Not all pet food is made equally. A lot of it is full of corn, by-products, dyes, unhealthy preservatives, filler grains and all sorts of nasty stuff. A lot of pet food companies are perfectly happy to the dump cheap leftovers and things that aren't safe for human consumption (from human food processing plants) into their foods. Will it kill your dog? No, it has to be nutritionally complete and safe to even be marketed. Is it healthy? Not by a long shot.
Corn is a low quality ingredient you never want to see in your pet food. Corn and low quality grains are two of the biggest culprits when it comes to food allergies in our pets.
Thankfully, there are some excellent dog foods being made these days that include organic, human grade ingredients rather than trash not fit for human consumption.
Examples of low quality foods to avoid: Anything you can find in a grocery store will be low end, Purina, Iams, Eukanuba, Science Diet, Royal Canin, Pedigree, Kibbles n' Bits, Beneful, Ol'Roy.
Examples of high quality foods to look for: Innova, Wellness, Solid Gold, Canidae All Life Stages, Fromm Four Star, Merrick, GO Natural, Nature's Variety Prairie, Nature's Logic, Artemis Fresh Mix, Timberwolf Organics.
Although the high quality foods are more expensive, you're getting what you're paying for. Less filler material means more concentrated nutrients… this means you typically need to feed far less of the high quality food than you would of the low quality one. Which also means less poop!
Seriously on a budget? Two of the most affordable of the high quality foods would be Chicken Soup for the Dog Lover's Soul and Canidae All Life Stages.
Before following your vet's food recommendation, keep in mind that vets get /very/ little nutritional training during their schooling. Besides that, what training they /do/ get is usually sponsored or taught by the crappy pet food companies! They also often get paid to sell some of their products at their clinics (Science Diet, Royal Canin etc.)
A great option is to go with an entirely grainless diet. Many of the high quality foods now put out grainless formulas. Some good grainless diets include: Innova EVO, Wellness CORE, Blue Wilderness, Nature's Variety Instinct, Orijen, Horizon Legacy, Merrick Before Grain, Canidae Grain Free All Life Stages, Fromm Surf & Turf, Now!, Sold Gold Barking At The Moon, Ziwipeak, and Taste of the Wild.
Some pretty decent foods can even be found in common pet stores. Petsmart carries Blue Buffalo products (such as the excellent grain free diet Blue Wilderness). Petco carries Wellness, Solid Gold, Natural Balance, Eagle Pack Holistic Select, Blue Buffalo, Castor & Pollux Organix, Pinnacle, and Halo. If you can't find a food, most of the high quality food brands have websites with store locators on them.
Another option, if you can't find anywhere around you that sells good foods, is to order your pet food online. Here's an excellent place to do so: http://www.petfooddirect.com/store/
Remember that foods should be switched gradually (mixing new slowly in with the old over about week or so), especially when switching to a higher quality one, so as not to upset tummies.
Another option for feeding dogs is to feed raw. This is something that should be thoroughly researched before being attempted:
http://www.rawfed.com/ (Excellent raw feeding information)
http://www.rawlearning.com/ (More excellent raw feeding information)
http://rawfeddogs.net/ (Even more!)
http://rawfed.com/myths/preymodel.html (Raw Prey Model Diet Vs. BARF Diet)
http://www.rawfed.com/myths/index.html (Myths about raw feeding)
Also remember that freefeeding (leaving food down) is the fast lane to canine obesity. Make sure to have scheduled feeding times based on the feeding instructions on your dog's food.
More on dog food:
http://www.dogfoodproject.com/index.php?page=main (Learn how to determine the quality of your dog's food.)
http://www.dogfoodanalysis.com/dog_food_reviews/ (Dog food reviews. Four stars is a decent food, five stars is a great food, and six stars is an excellent food.)
Darksong~
A few clips of our 9 month old Great dane – Zena. Born March 6, 2008. Her littermate/sister is the black puppy in the original slideshow that this is a response to. She eats right now between 6 1/2 – 7 1/2 cups of eagle pack puppy food (designed for danes) per day. She’ll be getting spayed in a few weeks, and we’ll get her weighed officially then, but she’s around 85 lbs right now.
Jennifer speaks with Chef Brent Wertz of the Kingsmill Resort in Williamsburg, Virginia about his innovative pairings of beer with food. Chef Brent explains the best way to pour a beer, and shows that beer can even go well with dessert! 
