A number of tactical gear makers offer K9 lines which are, for the most part, built for large dogs. Certainly, most working dogs are larger breeds but the civilian dog owner who just wants to look cool probably accounts for far more sales. Civilian dogs come in all sizes, including extra small.
United States Tactical is now offering their K9 Mesh MOLLE Vest in size XS or what they affectionately call “Flashbang” size. The vest has all the features of the larger version including beathable mesh construction, loop covered PALS webbing, built in handle, and D-ring attachment points.
I imagine an especially angry Dachshund, thrown into a room before entry, might be a reasonably effective distraction device.