Our Australian Shepherd, Matilda, is not the fiercest of protectors. In fact, she's a total coward. She flees in horror from strangers and is terrorized by the vacuum cleaner; even a pair of shoes left in an unaccustomed place can strike fear in her heart. But let her see a cat in the back yard, or even catch the scent of one on a walk, and my cowardly Matilda becomes a superhero ready to save me from the feline menace.

So when Matilda started pulling her superhero routine in the house a few weeks ago, running from room to room and growling at the air registers in the floor, I was immediately suspicious. We don't own a cat, and Matilda's seeming insistence that one was living inside our duct work was a little unnerving, to say the least.

A few days of watching Matilda pounce on air registers convinced me, and I suited up my husband and sent him under the house to investigate. It turns out Matilda was right. A neighborhood cat, seeking somewhere warm to have a nap, had been sitting on the duct work for our furnace. Apparently, the cat's weight had caused the duct work to separate, and the cat had crawled right in.

Not only did we have a cat intermittently bedding down in our duct work, but we were also losing a lot of heated air. Instead of that heated air circulating through our home as it was meant to, it was leaking into our crawl space.

As you might imagine, a quick trip to the hardware store followed for supplies to reseal and reinsulate our ducts.

Then there was a trip to the pet store for a tasty treat to reward Matilda, the true hero of the day. Had it not been for her quick-witted cat detection, we might not have noticed our duct problems until we saw our next utility bill.

Of course, we might have saved ourselves the trouble had we conducted some preventative maintenance and energy auditing prior to turning on the furnace for the season. Next year we'll be more prepared.

In the meantime we can rest easy knowing that Matilda, our intrepid cat detector, is monitoring the air registers.

Amy Foster Parish is on staff with the Washington State University Extension Energy Program and answers inquiries through the EERE Information Center.