Harriett demonstrates a warning nip to Gwen's finger. She is gentle and yet makes her point. Harriett's human, Shannon, says that if the human doesn't move away, Harriett will sink her teeth deeper, and then deeper, until she does draw blood. We think this indicates Harriett was abused in a previous life, before she was rescued by Shannon. A happy, well socialized rat does not use her teeth in this fashion.

Rats have extreme micro-control over their teeth pressure, so however they bite - drawing blood or not - is conscious and deliberate on their part. Harriett did not draw blood here, so she didn't want to draw blood. She wants to do the right thing but also wants the human to understand her limits.

For more on healthy and good ways well socialized pet rats use their teeth, visit: http://www.joinrats.com/EarningTrust/RatsUsingTeeth/15630450_hH8bsw.