Maisie has swapped her sheep-herding duties for a watch-dog assignment. Whether she likes it or not.

Raccoons, possums and other wildlife frequently amble in the barn to peruse the vittles selection and we don’t make it too hard for them. The cat food dishes line the hayloft stairs — buffet style. And if those are empty, they pop the top off the cat food bin and plunder our stash.

When I find the evidence of a nocturnal nosher, the solution is simple: the weight of a brick or a large rock will discourage dexterous paws from opening it up — though one creature — likely a raccoon — retaliated the next night by scaling the feed stall door, rummaging through the horses’ supplement containers and otherwise trashing the place.

Last night, however, I was splashing through the lake that was once our driveway, enroute to feed the horses, when a cat darted out of the barn, narrowly missing me. It looked like Mel but I then I realized that none of our cats are that fleet on their feet. Nor are they chased by thick bushy tails. The But musky scent in the air clinched it: I had surprised a fox who came within a few feet of a very up close and personal meeting with me.

And this was not a trial run, according to the overturned cat food container I’d found that morning. This guy was a regular visitor.

While it’s doubtful that the fox would attack a cat, I didn’t want to take any chances. So I assigned Maisie sentry duty, tethering her to the front of the barn last night. She looked baleful when we left there, ears drooping against the misting rain.

But in the morning all the cats were unaccounted for and their food in tact. Thanks to one filthy-muddy, rain-soaked Border Collie.

She did such a good job…I think we’ll put her on the case again tonight.