The veterinarian who connects Mike with criminal contacts in Better Call Saul is Dr. Caldera.
Played by Juan Carlos Cantu, Dr. Caldera runs a veterinary clinic in Albuquerque. Mike initially uses him as a discreet source of underworld introductions. Through Caldera’s contacts, Mike can locate people with specialized criminal skills, including the services needed for jobs involving surveillance, theft, and intimidation.
Dr. Caldera is not portrayed as a major cartel leader or lawyer. His importance comes from his position as a practical intermediary who knows many people operating outside the law. He also has a personal interest in eventually leaving that world.
The character is easy to confuse with other Albuquerque professionals, such as veterinarian and criminal associate contacts mentioned in the wider Breaking Bad universe. Caldera’s distinctive role is the referral network he maintains.