He was a tall, gangly, flea-bitten shepherd mix. One ear stood up, shepherd style, and the other flopped over and bounced against his head like a rag doll when he ran. His head and feet were too big for his thin but muscular body. A stale, musty odor accompanied him from flea-infested skin and neglected ears. Altogether, he wasn't much to look at - one of thousands of dogs facing the world without the luxury of an owner.

I was in my third year of veterinary school, and he came from the local dog pound. For the next quarter, four of us students would practice surgery training. He was always happy to see us - tail thumping widely against the walls of his small steel cage.

Rodney hadn't much of a life, so a pat on the butt and a little walk around the college complex made his day.

The first thing we did was neuter him, a seemingly benign project, except it took us an hour to complete the usual 20-minute procedure, and an anesthetic overdose kept him out for 36 hours. Afterward, he recovered his strength quickly and felt good.

Two weeks later, we did an abdominal exploratory, opening his abdomen, checking his organ inventory, and closing him again.

This was the first major surgery for any of us, and, with inadequate supervision, we did not close him properly. By the next morning, his incision had opened and he was sitting on his small intestine. Hastily, we sewed him up again, and he survived. But it was a week or more before he could resume walks he had come to eagerly anticipated.

He would still wag his tail when we arrived and greet us with as much enthusiasm as he could muster.

The following week, again when he was under anesthesia, we broke his leg and repaired it with a steel pin. After this, Rodney seemed in almost constant pain, his temperature rose, and he didn't rebound as he had in the past. His resiliency gone, despite antibiotic treatment, he never recovered completely.

He could no longer manage his walks, and our visits generated only a weak thump of his tail. The shine was gone from his brown eyes. His operated leg remained stiff and swollen.

The quarter was ending, and Rodney's days were numbered. One afternoon we put him to sleep. As the life drained from his body and his eyes lost their focus, my attitude toward animal research began to change.

I am a scientist weaned on the scientific method. ... But after 15 years in the veterinary profession, I now believe there are moral and ethical considerations that outweigh benefits.