Possible levetiracetam overdose....

Hi i am caring for a good friends dog and she takes levetiracetam at 3pm, 11pm, and  7am; Well, at 3 pm, i gave her 1.4ml (her dosage), and 15 minutes later my niece told me not to give her any medicine because she had already given it to her. I'm not familiar with this medication and especially in canines, but i know anticonvulsants can be fatal in an overdose. What are some of the symptoms of overdose should i monitor her for? Today is a holiday and the vet's are closesd.. so i'm very anxious right now!! She is 15 years old and takes many differrent medications. (A little info about her).  Thanks so much for your time!