Pet owners know this.

It is that your pet — dog or cat — know when you’re hurting.

My wife and I are the proud “parents” of a 13-year-old cat, Mittens, and a year-old pooch, Toby. But until this past November, we owned two cats. Mittens had a brother we adopted along with her from the ASPCA in the summer of 2002. His name was Socks.

One early evening, without warning, Socks went to one of his favorite sleeping places, curled up — and died. Just like that, he was gone. It devastated my wife and me.

We loved Socks very much and those of our friends and family who met this big brute of a cat understand why. He was absolutely the most lovable kitty I’ve ever seen, let alone taken into our family.

I miss him every day.

What’s the point here?

Well, I think his sister, Mittens, misses him, too. In fact, I believe Mittens has been demonstrating in recent months a keen intuition about us and the grief we’re still feeling.

She’s gone through a bit of a personality change since her brother died.

Of the two cats, Mittens was by far the shy one. She wasn’t nearly as demonstrative in her affection toward my wife and me as Socks. Sure, she’d like to be around us, but she was far more reserved.

To this day, she still doesn’t come out when company is in the house. She hides. When the coast is clear, then she shows herself, nibbles on her food, answers nature’s call … all the things cats do.

Of late, though, she’s becoming far more affectionate toward her “mother” and me. She nuzzles constantly. She demands attention from us. She is more vocal than before. When I climb into bed, usually to read a little before nodding off, Mittens jumps up, nudges my hands, snuggles against my cheek and neck and seems to say “I love you” as she purrs loudly in my ear.

I am no animal psychologist, obviously. My wife and I have owned cats almost throughout our 43-plus years of marriage. Toby the pooch is a new experience for us, but we’re getting along quite well with our Chihuahua mix. He’s adorable, smart and quite well-behaved. Does he miss Socks? Hardly.

However, Mittens is showing signs of recognition of the loss we have suffered and I believe she wants us to know that she loves us, too.

Now I know why pets can be so therapeutic.