Help! Are Greenies bad for small dogs?

My little sister give Greenes treat for my 4 year old 2lbs Chihuahua mix! She have given my dog the 5-15 lbs teenie one that say on the label that its not suitable for dogs less then 5lbs! I'm really worry she told me that my dog was chewing it first then she swallow half of it! I was wondering is it digestible? I'm so worry can she die from it or have stomach problem? Do I need to take her to the vet?