The up-close, funny photos of happy dogs are obviously chosen with intention, but I do think that this concept needs to be fleshed out.
The fonts should be uniform throughout - the first one gives off a soft, delicate feel because of the light weight and the opacity.
I think the bolded type for the last one fits best with the overall concept--maybe you could even use a really obnoxious font like Comic Sans.
Structure
The visual priorities are obviously the dogs' faces.
I think the type is pushed too much towards the bottom - I don't think you should be afraid of allowing the text to go on top of the dog's face.
You should add quotation marks and the speaker's name on the first one as well. If there is a reason as to why the first one doesn't have these (and are slightly transparent), make it more obvious!
Aesthetic
Again, I think you could go totally crazy with your concept and make it look like it has really bad (but totally intended) design.