I recently had to bottle feed a Frenchie puppy and found that my mini crock pot did a great job of warming the bottles. I would leave it on all day so it was ready at any time . I used a digital meat thermometer set at 100 degrees . Worked great- no guessing. I also used a mini bottle. The kind you give babies medicine in. Regular size nipple but only holds 15 mls of formula so you know exactly how much the puppy is getting. Less wasted formula.
photo credit: Renee V