Sentence:  Bolting can be one of the worst problems in dogdom to solve. We′ve all seen a <WSD>bolter</WSD> — or rather, we haven't seen him. We released him to hunt, and he was gone for the day, the week, the month. I′ve known of <WSD>bolters</WSD> to be gone for years. 
Meaning of the word marked with <WSD> tags:  A person or thing that bolts, or runs suddenly.