Role in the film
Dr. Kozak and the whole corporation were being charged because of unauthorized mutations with animal genes. He kidnapped a dog from Tibet who is believed to be 300 years old, trying to use his genes to develop a potion for immortality.
The dog escapes the lab and Kozak orders his goons to find him. His many attempts to capture "Shaggy" (the dog's name given by the Douglas family) resulted in the "accidental" capture of Dave Douglas, that was bitten by Shaggy and became a dog himself. Kozak's team finds the real dog and takes him back to the lab.
Hidden in the laboratory, Dave witnesses Dr. Kozak injecting company president Lance Strictland with a drug that will paralyze him for several months, giving Kozak enough time to usurp control of the company. After viewing security cameras, Kozak and his minions realize that somehow Dave became an exact copy of Khyi Yang Po. Kozak orders his goons to go to Dave's house to "pay him a visit."
Dave is taken to the lab to be euthanized, but Kozak has a court summons, and must deal with Dave later. Right before he leaves, Kozak mocks Dave in canine form Dave Bites him. He then begins to exhibit the same issues Dave had at the beginning of his adventure; Dave had successfully transferred the gene sequence into Kozak.
Dave, with the help of the dog-mutated animals, manages to escape as a human and races to the courthouse in his car with the mutated animals. He calls his wife and kids, tells them to meet him at the courthouse with clothes and the dog. He gets caught in a traffic jam and changes into a dog to get to the courthouse in time, where his family are waitng for him.
In the courtroom, Dave calls Kozak back to the stand and tries to get him to admit what he has done, but Kozak manages to hide his secret. Thinking fast, Dave mocks Kozak by implying he was working under Strictland's shadow, and angers him. The two begin growling at each another, and the judge, exasperated by Dave's canine behavior, orders the bailiff to remove him. But Dave thinking fast, throws Kozak a nightstick like a common stick, alerting his dog senses to get it, thus causing him to grow a tail. Kozak is immediately arrested soon after. As he's being taken away, Kozak swears vengeance on Dave before asking the bailiff "are we going outside?"