WALNUT, Calif. — Lukas was all bite, buck and bitterness before Karen Murdock adopted him six years ago and made him an Internet star.

Murdock introduced the 16-year-old Thoroughbred to carrots and kindness, helped him forget years of abuse and taught him tricks: He can smile, yawn, kiss, nod, identify shapes, numbers and letters, fetch, wave, salute, pose and stretch — and he does some of it with his front feet on a pedestal.

The 1,200-pound gelding has a Web site, is a star on Facebook, YouTube and Twitter and has been on TV. He and Murdock get up to 200 e-mails a day.

The story of Lukas has to be patched together in places. California bred, he ran in three races as a 2-year-old under the name Just Ask Mike, but "he was a back of the packer. His heart wasn't in it," Murdock said.

Between 1995 and 2001, he probably changed hands a couple of times. When a Southern California horse trainer saw Lukas in a yard, "He was malnourished, neglected and emaciated. His tail was a solid mat of mud and debris," Murdock said.

The trainer bought him, then sold him to Murdock for $2,000 in 2003.

"I had to let his mane grow long so I would have something to hold on to when he did this wild, spinning, bucking kind of thing," Murdock said. "He would spook in his own stall. He had a whole lot of fears and phobias. You couldn't touch his ears. There were no scars, just mental worries, apathy and mistrust."

It took her a year to untrain him.

"I use trick training as a tool to bridge what is not right into what I want," said Murdock, who has been working with horses since she was a teenager. "Lukas flourished. He cannot get enough of learning. He's like a sponge."

Now he is a liberty horse (performs without tack) who can do the Spanish Walk (front and back), passage (a hesitating trot) and jambet (a three-legged pivot). He also does the bow, obeisance (curtsey with his face between his legs) and rear (goes up on his hind legs).

The Human-Equine Alliances for Learning in Chehalis, Wash., which offers programs in psychotherapy and personal growth, asked to study Lukas. Lukas and Murdock show the "connectedness" that enables horses to be so therapeutic for humans, HEAL spokesman David Young said.

But it's unlikely the study will clear up history's mystery question about smart horses.

There is no scientific data to support the notion that horses have the cognitive ability to count, spell or read, Dr. Emily Weiss, the ASPCA's equine behavior expert, said in a telephone interview from Benton, Kan.

She looked at Lukas' Web site.