Professor Yan says real sniffer dogs also have other needs.
Fingertip searches and sniffer dogs are being used by police in the search.
Rescue teams with sniffer dogs yelled as they dug. "Is there anyone here?"
A 43-member German search-and-rescue team, with three sniffer dogs, arrived within 24 hours of the earthquake.
Rescue teams with sniffer dogs have been searching for signs of life and dozens of excavators are reported to be digging through the debris.
Tianjin plans to build the world's largest animal cloning factory next year for the cloning of beef and dairy cattle, sniffer dogs and racehorses.
The hunt for survivors entered its fourth day Wednesday, with troops still searching the ruins with life detectors and sniffer dogs.
One rescue worker in Beichuan, Luo Tanfei, says his team, which includes sniffer dogs, has saved 10 people in different locations since the huge earthquake struck the region Monday.
There they conduct exercises in a simulated disaster zone which are an eerie echo of real tragedies: sniffer dogs scrabble over collapsed buildings and rescuers call out to potential survivors.
