Question: Daddy was an American Pit Bull who was integral to the work of what Mexican-American dog behaviorist with over 25 years of canine experience?

Context:
Cesar Millan
Cesar Millan ( ; born César Felipe Millán Favela, ] ; August 27, 1969) is a Mexican-American dog behaviorist with over 25 years of canine experience.
 He is widely known for his Emmy-nominated television series "Dog Whisperer with Cesar Millan", which was produced from 2004 to 2012 and is broadcast in more than eighty countries worldwide.
 Millan is a New York Times best-selling author and has his own line of dog products and instructional DVDs.
 Prior to "The Dog Whisperer" series, Millan focused on rehabilitating severely aggressive dogs and founded a rehab complex, the Dog Psychology Center, in South Los Angeles (2002–2008).
 In 2009, the Dog Psychology Center moved to Santa Clarita, California.
 Millan also opened an East Coast clinic at the Country Inn Pet Resort in Davie, Florida, near Fort Lauderdale.
Histiocytoma (dog)
A histiocytoma in the dog is a benign tumor.
 It is an abnormal growth in the skin of histiocytes (histiocytosis), a cell that is part of the immune system.
 A similar disease in humans, Hashimoto-Pritzker disease, is also a Langerhans cell histiocytosis.
 Dog breeds that may be more at risk for this tumor include Bulldogs, American Pit Bull Terriers, American Staffordshire Terriers, Scottish Terriers, Greyhounds, Boxers, and Boston Terriers.
 They also rarely occur in goats and cattle.
Morghem's .500 Nitro Express
Morghem's .500 Nitro Express known as Frank's Khing at owner/call name registered events, is a UKC registered male American Pit Bull Terrier.
 Who competes in dog sports and conformation shows earning titles in Dock Jump, Lure Course, Show Champion, Rally Obedience and Weight Pull.
 Khing has been awarded the AKC Canine Good Citizen and USTTA temperament tested certifications.
Chamuco
The Chamuco (a Mexican word which means "devil") or Mexican Pitbull is a dog breed not recognized by any Canofile association.
 It originated in the center of Mexico, it was developed in this country in the 1970s, product of the accidental or intentional crosses of the American Pit Bull Terrier with the now extinct Mexican Bulldog, street dogs, American Bully, Pitbull Blue, Staffordshire bull terrier, American Staffordshire Terrier, and probably with the Boxer.
 Its name comes from the Mexican slang "Chamuco", which means devil because of its temperament and tenacity.
 Also it called Mexican pitbull or miniature pitbull, but actually is Dogo of Mexican origin.
Pit bull
Pit bull is the common name for a type of dog.
 Formal breeds often considered in North America to be of the pit bull type include the American Pit Bull Terrier, American Staffordshire Terrier, American Bully, and Staffordshire Bull Terrier.
 The American Bulldog is also sometimes included.
 Many of these breeds were originally developed as fighting dogs from cross breeding bull-baiting dogs (used to hold the faces and heads of larger animals such as bulls) and terriers.
 After the use of dogs in blood sports was banned, such dogs were used as catch dogs in the United States for semi-wild cattle and hogs, to hunt and drive livestock, and as family companions.
 Despite dog fighting now being illegal in the United States, it still exists as an underground activity, and pit bulls are a common breed of choice.
American Dog Breeders Association
The American Dog Breeders Association(also known as ADBA) was started in September 1909 as a multiple breed association.
 The residing president, Guy McCord, was an avid fancier and breeder of the American Pit Bull Terrier and was a close friend of John P. Colby.
 Colby was the mainstay of the ADBA and therefore it was considered the "home" registration office for the Colby dogs.
 All members in good standing could register their dogs and litters for the yearly fee of $2.50.
 The exclusive member’s idea gradually was replaced by a registry open to all owners and breeders of purebred dogs.
 Over time the association focused on the registration of the American Pit Bull Terrier.
Daddy (dog)
Daddy (1994 ‒ February 19, 2010) was an American Pit Bull Terrier integral to dog trainer Cesar Millan's work and his television series, "Dog Whisperer".
 Daddy became known for his calm temperament, tolerance for smaller dogs and capacity for empathy.
Bull and Terrier
The Bull and Terrier is a breed of dog that was the progenitor of the American Pit Bull Terrier, American Staffordshire Terrier, English Bull Terrier and the Staffordshire Bull Terrier.
Olde English Bulldogge
The Olde English Bulldogge is a recently created American dog breed.
 In the 1970s David Leavitt created a true-breeding lineage as a re-creation of the healthier working bulldog from early nineteenth century England.
 Using a breeding scheme developed for cattle, Leavitt crossed English bulldogs, American Bulldogs, American Pit Bull Terriers and Bull Mastiffs.
 The result was an athletic breed that looks similar to the bulldogs of 1820 but also has a friendly temperament.
American Pit Bull Terrier
The American Pit Bull Terrier (APBT) is a dog breed.
 It is a medium-sized, solidly-built, intelligent, short-haired dog whose early ancestors came from the British Isles.
 When compared with the English Staffordshire Bull Terrier (another breed within the type commonly called pit bulls), the American Pit Bull Terrier is larger by margins of 6 - in height and 25 - in weight.
 The American Pit Bull Terrier varies in size.
 Males normally are about 18-21 inches (45–53 cm) in height and around 35-60 pounds (15–27 kg) in weight.
 Females are normally around 17-20 inches (43–50 cm) in height and 30-50 pounds (13–22 kg) in weight.

Answer: Cesar Millan