One morning last week I sent Bonnie as usual to gather the goats. It's been seriously cold, for coastal California, cold enough for me to have to break the ice on the water buckets, and one would think the goats would tend to loaf on the thick bed of straw in the barn, but no, they found a place under the redwoods way at the top of the hill they preferred. They were hard to dislodge from there at the best of times, but this time, I heard some crackling branches and then Bonnie came racing out of the forest as if monsters were behind her. No goats. What the heck?

I soothed Bonnie, pointed her toward the goats whom I could see peering out of the trees, and back she went again, slowly. But now the goats were coming down by themselves. I led them down the road, and Bonnie followed after, all as usual. But something felt wrong. At the turn off the road up to their day field, a turn they never particularly liked to make, they just kept on going, toward my sleeping neighbor's back yard apple trees. "Bonnie, get around!" I hissed. But Bonnie turned away, sniffed the ground, and pretended there were no goats.

I cannot describe the sinking sensation I felt. It was like getting a phone call from the police when your child is out late. I had become so completely habituated to my dog automatically taking care of my livestock for me that I panicked and my mind went blank. But after a few futile commands, which she pretended she hadn't heard, I literally chased her past the goats—she gave them a wide berth—and then, as they automatically turned away from her, I began to trot away, hoping the goats would follow me. They did. I led them up the accustomed path, closed them into their electric fence, and went back home feeling like the end of the world.

What had happened to make her decide that she couldn't herd goats any more? I had seen nothing. But slowly over the next few days I began to piece together the evidence. Since my goats had never attempted to butt her, nor did they subsequently challenge her, I figured there must have been some sort of accidental collision. My young goats often spring randomly into the air and bounce, and perhaps one or more had crashed into Bonnie when she was least expecting it. Whatever it was, she had interpreted it as very scary indeed.

I tried her on the goats again when they were safe back home. She acted as before, as if aliens had replaced her stockdog brain with one from a cocker spaniel. She sniffed fascinating holes, ate grass, and vaguely followed me around. When a goat moved toward her, she shied away as if it was radioactive. It was incredibly difficult to move goats without a dog. They did exactly as they pleased. It was like a bad dream I couldn't wake from. There was no way I could graze my goats anywhere, without my dog.

Over the next couple of days I kept casually bringing Bonnie into the goat field, and then ignoring her. She was nervous, but slowly relaxed as nothing bad happened. Eventually I tried getting excited and grabbing a goat. At first she was hesitant, but then she began to get back a little steam, and started trying to pitch in and help. Every single step she made toward the goats, I praised to the skies. It was obvious now which goat had collided with her: she began to move in authoritatively on the other two, while avoiding just this one. Then, after a few tentative nips proved that nothing had really changed about Tule either, I could see she was rethinking the whole issue.

Still, I hadn't taken the goats out into the open again. Instead I went up to Gwen's, and worked her sheep. Here Bonnie was in her glory. We sorted lambs, took the whole flock for a long walk, and practiced gathers and fetches—easy stuff. At the end of the practice, I was talking to Gwen, and out of the corner of my eye saw Bonnie slowly sneak off to gather the flock at the other end of the arena. I let her do it. She didn't rush anything. She eased up, veered out and smoothly headed a couple sheep going the wrong way, and brought the whole flock of nearly thirty sheep and lambs up to me at a jog trot. Atta girl.

On the way back to the car, we saw that three ewes who had gotten loose earlier that day (before I'd gotten there) were still wedged back behind between a fence and a bramble-choked creek, unable to figure out how to get out. I offered to let Bonnie have a try at winkling them out. At first she couldn't see them—I don't have any way of directing her toward sheep she can't see, and the wind was blowing toward the sheep. After some false starts, she put her nose to the ground and began to track them. She disappeared, reappeared with the sheep, and then we ran into the problem: they would not cross the creek. It was dark and tangly and wet and they were having none of it. After Bonnie had turned them back five or six times I gave up on that idea, and walked downstream until I found an easier crossing. Problem solved. I'd forgotten how much sheep hate to go into dark places.

Once the sheep crossed the creek they were happy to run back to their home pasture themselves, and I put my dog in my car and drove home. I felt better.

I think Bonnie will work my goats again. Maybe even tomorrow. But I have to be careful with her, I see. Like every dog, she has her limit of what she will bear; she cannot be more than she was given to be. Just like the sheep; in fact just like every living thing. It is a big part of my job as a trainer and livestock manager to always keep in mind what those limits are.