A four-year hitch in the Marines and two tours in Vietnam left me callous about certain things. However, as I discovered last June while on a hike with one of our dogs, time and maturity can alter our reactions to death and tragedy.

I was walking down a trail with Tucker, our 70-pound Australian shepherd cross, below the H on Mount Helena on a fine spring day. Tucker was off leash about 100 feet from the trail, sniffing through the brush as he loves to do on off-leash outings.

I lost sight of Tucker for a bit but continued down the trail, confident he was close by and doing well. I came to a clearing in the brush and stopped to call him. I saw movement in the clearing about 50 meters from the trail and noticed a young mule deer fawn clumsily running down the hill. Not far behind was Tucker, not going full bore but keeping up with the fawn, a playful earnestness to his athletic gait.

I streaked toward him and the fawn, my first "leave it" piercing the warm, sunny air. Tucker reached for the fawn in a grab/bite when my second "leave it" hammered his way. He grabbed the fawn, shook it, and tossed it in the air before my third "leave it" finally moved him back away from the fawn.

When I arrived, the fawn was peacefully lying next to a bush. Tucker sat a few feet away, panting happily and seeming to admire his handiwork. The fawn looked in good shape from above. I noticed a doe about 100 meters above us, impassively watching, giving no visible hint it was the mom.

I was relieved the fawn looked OK. I slowly turned it over to examine the underside. Then it happened. Part of the fawn's intestines spilled out of a rip several inches long in the belly. In all other respects the fawn appeared healthy.

For a short time I considered carrying the fawn down the half-mile trail to the car and driving it to a vet. What was the humane thing to do? Sometimes the answer to that question is grey and murky, not a clean textbook solution. I decided to use a rock, a little bigger than my hand, to finish the fawn. The doe above us watched, seemingly impassive.

After the anger at Tucker and myself subsided, I sat down and wept. This was a useless death, not prompted by natural predatory activity which may have eventually gotten the fawn anyway. Deer fawns are vulnerable in May and June, as their sea legs are still developing and their primary source of survival is hiding from predators, not running.

Some might be happy about the death, thinking it's one less deer that would have invaded town. Not me. The fawn died an unnatural death in its natural habitat. It deserved the chance to grow up or be cut down by the natural forces in its environment.

Moreover, my "leave it" command reflected incomplete training and did not pull Tucker off the fawn fast enough. I should have known that wildlife vulnerable to prey can be hiding close to major trails that time of year.

Sometimes dogs act like animals when instinct or fear take over. It's our absolute duty and responsibility as owners to make sure their behavior is managed in a way that doesn't unnecessarily hurt others.

Now that I know better, Tucker will be on a leash while hiking in the hills this May and June. This is one mea culpa I will not have to repeat.

Tom Kandt is a certified pet dog trainer and graduate of the San Francisco SPCA Academy for Dog Trainers. He is shelter trainer and behavioral consultant at the LC HS. Reach him at tkandt@yahoo.com.