Photos: Jack Hanna through the years
Celebrity zookeeper and animal TV show host Jack Hanna has been diagnosed with dementia and will retire from public life, his family said.
Television personality Jack Hanna attends G'Day USA: Australia Week 2008 at Jazz at Lincoln Center, Tuesday, Jan. 22, 2008 in New York. (AP Photo/Evan Agostini)
Renowned naturalist Jack Hanna of the Columbus, Ohio, Zoological Gardens, holds two Bengal Tiger cubs that were born and bred in captivity during a ground breaking ceremony at the Dallas Zoo Monday morning, Feb. 9, 1998. The Dallas Zoo will be home to the new Exxon Endangered Tiger Exhibit, a $4.5 million state-of-the-art tiger facility. (AP Photo/Tim Sharp)
Jack Hanna, left, and Deborah Gibson pose backstage at the 39th Annual Daytime Emmy Awards at the Beverly Hilton Hotel on Saturday, June 23, 2012 in Beverly Hills, Calif. (Photo by Todd Williamson/Invision/AP)
** FILE ** In this May 10, 2000 file photo, Nationally recognized animal expert Jack Hanna grabs the tusk of a black rhino after helping Busch Gardens Tampa Bay unveil plans for their newest attraction "Rhino Rally" in Tampa, Fla. David Letterman's producers like it when Jack Hanna's zoo animals run amok on the show because it's good for laughs. Hanna, director emeritus of the Columbus Zoo, recounts 25 years of television appearances in his new autobiography. (AP Photo/Chris O'Meara)
Jack Hanna poses with a penguin as he arrives at Safe Kids Day at Smashbox Studios on Sunday, April 24, 2016, in Culver City, Calif. (Photo by Jordan Strauss/Invision/AP)
Television personality Jack Hanna attends G'Day USA: Australia Week 2008 at Jazz at Lincoln Center, Tuesday, Jan. 22, 2008 in New York. (AP Photo/Evan Agostini)
Zoo keeper Jack Hanna arrives for a taping of "The Late Show with David Letterman" in New York, Monday, March 9, 2009. (AP Photo/Charles Sykes)
FILE - This file photo from March, 2009, shows Jack Hanna of the Columbus, Ohio, Zoo in New York City for a taping with David Letterman. The Ohio zoo is celebrating a No. 1 ranking with a new commercial all about getting rid of "number 2" _ the other kind. A cast, including Hanna, shovels and sweeps animal waste to lyrics such as "Lots of scoopin' all their poopin'" and "No more number 2." (AP Photo/Charles Sykes, file)
Jack Hanna, director emeritus of the Columbus Zoo, has his hands full as he protects a CD recording from Kabul, a white Bengal tiger, in Columbus, Ohio, Thursday, April 11, 1996. The CD of contemporary instrumental music, inspired by Hanna's television wildlife specials, is to be released for sales this weekend. (AP Photo/Jack Kustron)
Deborah Gibson, left, and Jack Hanna arrive at the 39th Annual Daytime Emmy Awards at the Beverly Hilton Hotel on Saturday, June 23, 2012 in Beverly Hills, Calif. (Photo by Todd Williamson/Invision/AP)
Deborah Gibson, from left, Jack Hanna and a guest arrive at the 39th Annual Daytime Emmy Awards at the Beverly Hilton Hotel on Saturday, June 23, 2012 in Beverly Hills, Calif. (Photo by Todd Williamson/Invision/AP)
Jack Hanna poses backstage at the 39th Annual Daytime Emmy Awards at the Beverly Hilton Hotel on Saturday, June 23, 2012 in Beverly Hills, Calif. (Photo by Todd Williamson/Invision/AP)
Wildlife advocate Jack Hanna poses for a portrait with a serval cub on Monday, Oct. 12, 2015 in New York. (Photo by Dan Hallman/Invision/AP)
FILE - Wildlife advocate Jack Hanna poses for a portrait with a snow leopard cub in New York on Oct. 12, 2015. The family of celebrity zookeeper and TV show host Jack Hanna said he's been diagnosed with dementia and will retire from public life. (Photo by Dan Hallman/Invision/AP, file)
FILE - Wildlife advocate Jack Hanna poses for a portrait with a cheetah cub in New York on Oct. 12, 2015. The family of celebrity zookeeper and TV show host Jack Hanna said he's been diagnosed with dementia and will retire from public life. (Photo by Dan Hallman/Invision/AP, file)
"While Dad's health has deteriorated quickly, we can assure you that his great sense of humor continues to shine through," his family said in a statement. "And yes, he still wears his khakis at home."