True dog lovers would love it if you made quilts for their dogs. However, some dogs eat fabric and some eat fluffy batting so if they're not used all the time, you will understand why. They may need supervision when they're using them. My basset hound cannot be allowed in my sewing room because he'll steal pieces of fabric when my back is turned and eat them. Could cause intestinal blockage. My golden will eat fluffy batting if she can get it.
Doggy coats can be made with velcro sewn on strapping for the underneath straps to hold them on. This is the same as our service dog program uses as puppy vests.
There are quilt patterns with dogs appliqued or pieced. You might want to do an internet search. (I love javahousequilts.com for the pattern with the dogs on it)