One of the hardest things a pet owner faces is the end of the life of her animal companion. It is easiest when our companion just drifts off and doesn't wake up one morning after a long and happy life. Unfortunately, this rarely happens.

It is not unusual for an animal to slowly age, have no real complaints, but simply not be as quick to play fetch or go for a walk. We notice they sleep more and getting up isn't as easy as it used to be.

Sometimes veterinarians prescribe non-steroidal, anti-inflammatory drugs, such as Rimadyl and Etogesic for dogs, or phenylbutazone or "bute" for horses. These work effectively on pain, but do not solve the cause of the pain. Joint protective nutriceuticals like glucosamino glycans and cetyl myristoleate can be useful. But, the bottom line is sometimes we need to know when to say when.

Sometimes there's no doubt. Last week, my practice partner Stephanie called me. She told me that the man where she keeps her horses just called and said her beloved gelding, Star, was colicking. I was instantly concerned. In his 20 years on this planet, Star has never colicked. He's been Stephanie's adored equine companion since he was 6 months old.

I was in a meeting, but as soon as she called, the meeting was over for me. I listened to the discussion we were having, but my mind's eye was with Stephanie. I was not surprised when she called about 10 minutes later, no effort to hide the tears in her voice, "Come quick! He's down. It's really bad," she said. "Please come!"

I can't remember leaving the meeting. I'm sure I said something, but I just left. I got to where Star was pastured and saw him lying in the grass and snow with Stephanie by his head. She said she'd given him some medications for pain and he'd quieted down. I looked at him. He's a big red dun gelding with a wide blaze. He lifted his head a bit when I got there and sank back down. I did a quick physical exam while Stephanie ran for some warm water and mineral oil.

He didn't look like a typical colic. He was quiet, not rolling and thrashing in pain. His gut sounds were ominously still, but his mucus membranes didn't look bad. He just lay there.

I wondered for a moment if he was sick with some disease like botulism. It's not common, but when a horse gets it, the horse just lies there. He can't get up.

Then a woman stopped, walked over, and said he looked a lot better. She'd been driving by when she first saw Star and he was down, rolling and thrashing. She said she was glad to see him comfortable.

My heart sank. I quickly inserted a needle into his abdominal cavity and withdrew three ccs of fluid. It was brownish-green. It's supposed to be the color of pale apple juice. I knew then why he was lying so quietly: He'd ruptured his bowel. He was dying.

The painful part of some colics is when the bowel gets terribly distended by gas. The pain stops when the bowel ruptures, and while the horse is more comfortable, the resulting intense infection will kill him.

When Stephanie returned, I held up the syringe with its telltale fluid for her to see.

"It's his belly tap," I said gently.

She saw it and knew exactly what that meant. Star was dying; there was nothing any of us could do. She knelt down by his head, stroked his face and wept. She looked up and asked me to put him down. I had tears in my eyes as I drew up the euthanasia solution to ease his passage.

He passed away peacefully surrounded by people who loved him.

While it's shocking when our pets pass unexpectedly like that, it's somehow easier than when we have to make the decision to end their lives.

Part of the work we as veterinarians do is assist owners in facilitating good healthy lives for our animal companions. And then when the quality of life for our pets is no longer good, we help to make their passing peaceful and easy. Compassionate care is vital to our relationships with our patients and their owners.

We love our own animals as much as the owners of our patients love them. Losing our own animals can help us feel even more empathy for our clients when it's time to say when for our patients.

Tia Nelson, is a local veterinarian specializing in an integrated approach to animal health that combines traditional veterinary medicine with holistic, natural practices.