Whether it is friendly or not doesn't matter. It was out of control according to the law.
Your language is very emotionally intense, naturally of course. You are a mother to a young infant and you were frightened. ETA - you used the force that you deemed necessary at the time which is entirely ok and fine according to our law.
You appear to be insisting that any contact between infant and dog will always result in scratches which is obviously emotionally overwrought and not entirely true.
It is possible a dog could touch a baby without leaving a scratch. In this instance however, it did leave a scratch, which could potentially constitiute aggravated offence?
In other words, moving from “the dog touched my baby” to “the dog scratched/injured my baby” is legally significant.
I notice you have also gone from "jumping up" to "lunging".
It must exhausting being in a courtroom all day debating nuances, subtly of language, reasonable force etc. No wonder they are paid so well.
As Aristotle once said (I'm not high brow, anyone who has watched legally blonde will know this one) - "The Law is reason free from passion" - which is how this debate of the legality of wording has ended up unfolding!