Nilla is a phonetic clipping of vanilla — the flavor, the scent, the color. On a female dog, it almost certainly describes coat color: cream, off-white, golden, the particular warm pale that most vanilla-colored dogs carry. It belongs to the dessert-food naming category alongside Cocoa, Cookie, and Caramel.
The Food-Color Naming Logic
Food names for pets most often start as coat color descriptions. Nilla works for cream-colored dogs the way Cocoa works for brown ones — the word describes what you see. The Nilla Wafer brand (Nabisco) reinforces the connection: small, round, pale golden, sweet. A cream-colored dog with that description gets the name organically.
Sound Fit
Nilla has a soft onset, two syllables, and the same -a ending that makes so many female pet names work: Bella, Luna, Stella, Nilla. The n- beginning is gentle, not commanding, which suits female dogs and cats whose owners want a name that sounds warm rather than sharp.
The Counter-Reading: Brand Proximity
Some owners may want to distance their dog from the Nilla Wafer brand association — it makes the name feel more like a product than a creature. Those owners may prefer Vanilla spelled out, or shift to Cream or Ivory for the same color concept. At 40 registrations, Nilla is a clean, affectionate food-color name that works for exactly the dogs it's given to.