The birthday cake idea actually came from my friend's epileptic dog, who is restricted in what food he can eat. The Epileptic Dogs Support Group suggested making training treats from 'Chappie' dog food (not sure if you can get this in the States?). I had a go at making some then thought if it worked for Chappie, the principle would work for any wet dog food. So I substituted in the food my boys normally eat and it was successful!
The recipe is very basic. I mash the food up well, add a medium sized egg, add flour (plain or wholemeal) until it is a scone/bread consistency - quite stiff so it is reasonably hard to mix. You need about equal parts of dog food to flour and I generally add about 1/4 cup of water to stop it going too stiff. Also if making it really special a small pinch of garlic powder just lends some flavour. Line a sandwich tin with grease proof paper and pop in the mixture. In the oven on a medium heat (150C approx.) for about 10-15 minutes until it is firm when prodded but not crisp, cool off on a wire rack then cut as desired. It keeps in the fridge for about a week (and depending on how many dogs are eating it!) You can freeze it but I don't bother as they go through it far too fast!
I use the same principal for tuna cake (equal parts tuna in spring water to flour) and liver cake. The quantity for the latter is considerably more as there is a lot more liver in a pack so I cook that in a glass loaf tin. (Never has such good results from the metal ones for some reason.) That takes an hour to cook and you have to use a blender to puree the liver and it is a longer and more unpleasant process, but does keep well when frozen and they do love it.
Just a tip I found is to predict what I am mostly going to be using it for in advance and adjust the consistency accordingly. So for show bait or something where the pieces are going to be quite big, I don't make it as stiff (add more water or less flour) than if I'm doing lots of clicker training when I cut the pieces up very small (about 1/4 the size of a dice for shelties). To successfully cut it that small for any of the cakes the mixture needs to be pretty stiff and solid or it just crumbles. It does dry out quicker though. I used to carefully measure out the flour but now tend to go by feel, just adding more until it feels right but it is roughly equal to the amount of meat.
A benefit of using their regular dog food as a base for the treats is that if they are prone to stomach upsets this generally isn't an issue especially if you leave out the garlic and use rice flour. You can sprinkle a bit of grated cheese on top too before putting it in the oven - for special occasions!
