We don't do birthday cakes... I have 2 dogs that super sensitive stomachs. If I just give Gizmo or Bullie scraps from the dinner table, they'd have watery poop the next day, so yeah, they have a strict diet and it doesn't involve birthday cakes.
But, I did a search for dog birthday cakes and found one that looks yummy on a dog treat recipe site.
Sorry link removed.