An estimated 1.5 million people fled Louisiana before Hurricane Katrina bore down in 2005. Cars jammed on the New Orleans' Causeway in attempts to escape the Category 3 hurricane barreling toward the city sitting below sea-level. Citizens were told to take what they could and flee.
Amid the chaos leading up to landfall, thousands of pets were left behind in houses that eventually were enveloped in floodwaters from the broken levees. The Federal Emergency Management Agency (FEMA) had no plan in place to assist animals, only humans. Refugee centers were forced to separate pets from families.
The fate of these animals rested on a hodgepodge of animal welfare groups who had little experience working together.
Dr. Dick Green, senior director of disaster response for the ASPCA, arrived on the ground quickly after the storm struck and remained there for 47 days.
"We spent the first 20 plus days in relatively deep water. Then when the water started to recede our operations changed. We went from strictly floodwater rescue to a combination of water rescue and land rescue. So our mission changed," he told AOL.com.
Most flood waters subside within a week, allowing rescuers to transition to a land-based rescue, Green says, but Katrina was different.
"Katrina was the longest water-based rescue operation I've ever done. The water just hung around forever," he said.
The animal welfare groups also were overwhelmed by the outpouring of support from across the nation. Media coverage of the pets affected by Katrina like the infamous forced separation of a 9-year-old and his little white dog Snowball inspired a grassroots movement to help the animals left behind.
"It was such a heart-wrenching thing," Green said, recalling people from every state coming to help. "They filled up their cars with food and supplies, they drove all over the country and showed up and we didn't know how to put them to use ... We did not know how to manage all of these groups that came to help."
Over 8,500 animals were ultimately taken to the makeshift shelter set up at the Lamar-Dixon Exposition Center in Gonzales, La.
Another estimated 250,000 dogs and cats were displaced or died as a result of Katrina, according to the ASPCA, including an unknown number of other animals such as fish, small mammals and horses.
See the pets, and their owners, who struggled in the aftermath of Katrina:
Katrina 10 year: Animal welfare
Animal welfare groups unite in wake of Hurricane Katrina tragedy
This Feb. 15, 2013 photo provided by Best Friends Animal Society shows Celine, a dog who has had quite a journey. Born in 2005, she was rescued from the flood waters of Hurricane Katrina as a puppy. She was adopted and moved to Florida, but five years later, she was found as a stray in rough shape. At Utahâs Best Friends Animal Society, she is one of the last known adoptable survivors from the Aug. 29, 2005 hurricane. Since the storm struck on Aug. 29, 2005, laws have changed how animal welfare groups and emergency responders approach pet rescues. They also have received training to better catalog rescued animals. (Molly Wald/Best Friends Animal Society via AP)
This Jan 8, 2008 photo provided by Best Friends Animal Society shows Archie, a black Lab mix that was estimated to have been born in 2004. He was rescued by Best Friends Animal Society after Hurricane Katrina and first went to a rescue group in Arizona. Since the storm struck on Aug. 29, 2005, laws have changed how animal welfare groups and emergency responders approach pet rescues. They also have received training to better catalog rescued animals. (Molly Wald/Best Friends Animal Society via AP)
Phyllis Anderson and her 17-year-old cat, Trouble, are evacuated from their flooded home in Slidell, La., Thursday, Sept. 1, 2005, in the wake of Hurricane Katrina. (AP Photo/Mari Darr-Welch)
NEW ORLEANS - AUGUST 29: Lana Seymour and her dog Fifi peer out from their house to survey the damage in the French Quarter after Hurricane Katrina blew through the area early on August 29, 2005 in New Orleans, Louisiana. Katrina was down graded to a category 4 storm as it approached New Orleans. (Photo by Chris Graythen/Getty Images)
NEW ORLEANS - AUGUST 30: Al Duvernay (L) lowers Rusty the dog into his boat while rescuing people stranded by the Hurricane Katrina's floodwaters August 30, 2005 in New Orleans, Louisiana. Devastation is widespread throughout the city with water 12 feet high in some areas. Hundreds are feared dead and thousands were left homeless in Louisiana, Mississippi, Alabama and Florida by the storm. Looting has been reported in New Orleans, mostly empty due to the storm. (Photo by Chris Graythen/Getty Images)
New Orleans, UNITED STATES: A dog tied to the railing of a highway ramp barks in a New Orleans street 03 September, 2005 six days after hurricane Katrina hit the city. Thousands of soldiers poured into New Orleans 03 September while multitudes fled the city, leaving behind rotting bodies, flooded streets and homes and fears of disease epidemics. AFP PHOTO/Nicholas KAMM (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
New Orleans, UNITED STATES: US Airforce Lt. Nathan Broshear holds a kitten rescued and airlifted to New Orleans International Airport in the aftermath of Hurricane Katrina 04 September 2005 in New Orleans, Louisiana. AFP PHOTO/James NIELSEN (Photo credit should read JAMES NIELSEN/AFP/Getty Images)
UNITED STATES - CIRCA 2002: Ray Lambert is overjoyed to find at least one of his eight cats - Mamou - as he returns to his home on Keane Dr. in St. Bernard Parish for the first time since Hurricane Katrina hit 16 days ago. Lambert was on vacation with his wife in Maryland when the storm demolished his 9th Ward neighborhood. (Photo by Linda Rosier/NY Daily News Archive via Getty Images)
NEW ORLEANS - AUGUST 29: A dog sits stranded on a rooftop in the flooded Lower Ninth Ward in New Orleans, Louisiana on August 29, 2005. Hurricane Katrina slammed Louisiana as a category 4 storm, forcing levies to brake and flooding much of New Orleans. (Photo by Marko Georgiev/Getty Images)
New Orleans, UNITED STATES: Two mules who usually pull carriages for tourists through the French Quarter of New Orleans, Louisiana roam freely through the streets of the city 06 September 2005. US President George W. Bush said 06 September, he would investigate 'what went wrong' with the government's response to Hurricane Katrina, but he refused to say whether he would fire any aides involved. 'What I intend to do is to lead an investigation to find out what went right and what went wrong,' he said after a cabinet meeting, noting that the response to Katrina boded ill for any response to a terrorist attack in the future. AFP PHOTO/Nicholas KAMM (Photo credit should read NICHOLAS KAMM/AFP/Getty Images)
New Orleans, UNITED STATES: Officer Wiillie Cirone of the Humane Society of USA leashes an abandoned dog beneath a Highway 10 overpass in New Orleans 06 September 2005. According Cirone, for each animal they find abandoned, there are ten more in the streets of the devastated city, eight days after Hurricane Katrina. AFP PHOTO/ Omar TORRES (Photo credit should read OMAR TORRES/AFP/Getty Images)
Colby Fernandez, 3, left, gives his aunt, Rebecca Fernandez, right, and cat a hug, Monday, Sept. 12, 2005, in Roswell, Ga. Like countless other Hurricane Katrina evacuees, the Fernandez clan struggled to cope with the reality that their home, jobs and belongings were gone. Stranded in an Arkansas hotel, with their two cats meowing and little Colby restless, Christina and her sister weighed their options before deciding to drive 600 miles and move in with the strangers they found on the Internet offering spare rooms in their house. (AP Photo/Gregory Smith)
Jonathan Harvey wades through flood waters after rescuing his dog "Cuddles" from his flooded home after Hurricane Katrina struck the Gulf Coast Monday, Aug. 29, 2005 in Gulfport, Miss.. (AP Photo/John Bazemore)
Randy Fortier and Brandy McCoy pull C.C., a dog, back to their fishing camp on Wednesday, Aug. 30, 2005, in Slidell, La. The two friends evacuated their fishing camp during Hurricane Katrina. (AP Photo/Mari Darr-Welch)
Brian Mollerie holds his dog Rocky Wednesday, Aug. 31, 2005, in Waveland, Mississippi. He swam with Rocky from the second story window in his family's store to escape Hurricane Katrina. (AP Photo/John Bazemore)
UNITED STATES - CIRCA 2002: Abandoned dogs rescued from the floodwaters ride on the bow of a fishing boat in the submerged Mid-City district of New Orleans, La. Residents who evacuated the Big Easy in the wake of Hurricane Katrina were not allowed to take their animals along, so many of them were forced to choose between remaining at their barely-habitable homes or leaving their beloved pets behind. (Photo by Corey Sipkin/NY Daily News Archive via Getty Images)
UNITED STATES - CIRCA 2002: Dave Douglas, 42, who was told he couldn't bring his dog if he evacuated the area, explains that he's therefore choosing to remain at his flooded home in the hard-hit Ninth Ward neighborhood of New Orleans, La. As the Big Easy evacuates, already traumatized victims of Hurricane Katrina are making a choice: Head for safety or stay behind with a beloved pet. (Photo by Corey Sipkin/NY Daily News Archive via Getty Images)
U.S. Army flight surgeon Capt. Devry C. Anderson, of HHC 2-4 Aviation, 4th Infantry Division out of Fort Hood, Texas, holds a small dog named Chip after it was rescued with its owner, Friday, Sept. 2, 2005 in New Orleans. To the left and right of Anderson are victims of Hurricane Katrina peering out the windows of the Chinook as he flies to a new land zone. (AP Photo/Haraz N. Ghanbari)
Hurricane Katrina refugees Tracy Wilbur, left, and his wife, Jody Hestand, sit on their car with their two dogs Lexi, left, and Slater Friday, Sept. 2, 2005, in Bloomington, Ind. The couple made it to Bloomington with plans to stay in a local motel for the next few weeks. Hestand works at Tulane University with ties to Indiana University-Bloomington and is receiving help from IU with email and locating co-workers. (AP Photo/Monty Howell)
An east-side neighbor-hood dog makes his way over debris as he looks for a way out of the flooded area, Saturday, Sept. 3, 2005, in New Orleans, LA.(AP Photo/Phil Coale)
A stranded dog attempts to swim to safety from a flooded neighborhood, Saturday, Sept. 3, 2005, in New Orleans, LA.(AP Photo/Phil Coale)
Denyka Powell, 26, asks military police for information on how to be evacuated from the historic French Quarter in New Orleans, La., Sunday, Sept. 4, 2005. Powell said she would not leave without her snakes. (AP Photo/Rick Bowmer)
Donna Nicholson, a medic with a urban search team from Connecticut, gives water to surrey mules used to pulled surreys in the French Quarter as they roam downtown New Orleans, La., Sunday, Sept. 4, 2005, in the aftermath of Hurricane Kartinna. (AP Photo/Eric Gay)
Mat James carries his dog Baby Pearl as he marches in the Southern Decadence parade in the French Quarter of New Orleans, La., Sunday, Sept. 4, 2005. The week long gay festival, which is second only to Mardi Gras, was to have begun Sunday. (AP Photo/Eric Gay)
Hurricane Katrina evacuee Antoinette Simmons hugs her 7-year-old Shitsu dog, Princess, as her husband, Wilson Clark, not pictured, checks in the dog to stay at the Humane Society of North Texas in Fort Worth, Texas, Monday, Sept., 5, 2005. Clark and Simmons are from Jefferson Parish, about three to four miles from New Orleans. Placed by the Red Cross, they are staying with 14 of their family and friends at a nearby hotel. They plan to visit their dog at the Humane Society during their stay and eventually return with the dog to Louisianna. (AP Photo/David Pellerin)
Brad Fals, 32, leads a crate full of puppies and his dog Harley out of a warehouse where he had been staying with his grandfather and two other dogs in Chalmette, La. Monday, Sept. 5, 2005., after evacuating his home when Hurricane Katrina hit last Monday. Sept. 4, 2005, They are moving to another temporary housing location that will accept their animals. (AP Photo/Lynne Sladky)
Ruby Herpin of New Orleans is reunited with Sweetie, one of her five cats at the South Chattanooga Recreation Center, Tuesday, Sept. 6, 2005, in Chattanooga, Tenn. The Chattanooga Humane Society brought the two cats and three kittens down for a visit and are being housed at the Humane Society. Herpin will stay at the recreational center until she and the cats can be placed in a home. (AP Photo/Mark Gilliland)
Robert Fonteaine holds his puppy, Gangster, as he watches New Orleans firefighters try to save his house after it caught fire on the east side of New Orleans, La., Tuesday, Sept. 6, 2005. Fonteaine's house was a total loss. (AP Photo/Eric Gay)
Peaches, one of 17 cats and one dog belonging to Homer and Debbie Hollis of Biloxi, Miss., sits on a shelf at Pulaski County Humane Society's shelter Tuesday, Sept. 6, 2005, near Little Rock, Ark. The Hollis' who brought their pets when they evacuated their home last week and are staying in a shelter in Searcy, Ark. The couple visited their pets Tuesday. (AP Photo/Danny Johnston)
Lisa Hochstetler with United Canine, a volunteer search group from Ohio, and her dog Grisley search for victims of Hurricane Katrina in East Biloxi, Miss., Tuesday, Sept. 6, 2005. (AP Photo/M. Spencer Green)
Veterinarian Eugene Knispel feeds his neighbors cats in New Orleans Tuesday Sept. 6, 2005. Many of the besieged city's residents were reluctant to leave their pets behind as authorities continue to try and evacuate the flooded city. (AP Photo/Dave Martin)
Hurricane Katrina refugee Valerie Bennett, of Slidell, La., presses her face to her dog, Lady, after they were reunited at Emory Hospital in Atlanta, Wednesday, Sept. 7, 2005. She and her husband, Lorne, had to leave behind four of their pets when Lorne, a liver transplant patient, had to be evacuated in the wake of Hurricane Katrina, to a liver specialist for supervision. (AP Photo/John Amis)
A truck full of dogs and cats await unloading after a group called Much Love Animal Rescue airlifted the animals from the hurricane-affected Gulf Coast, at an adoption staging area in Torrance, Calif., Tuesday, Sept. 20, 2005. The animals arrived on a charter flight at Los Angeles International Airport, then were brought by truck to the staging area. (AP Photo/Nick Ut)
Animal rescue workers tend to a dog, dehydrated from the flight from Louisiana, at the San Francisco International Airport Sunday, Sept. 11, 2005, in San Francisco. Some of the animals who were displaced by Hurricane Katrina were brought to the Marine and Sacramento humane societies Sunday. (AP Photo/Julie Plasencia)
Staff Sgt. Dustin Mittag of Campbell, Mo., holds a kitten that he said came scampering across the interstate towards him while he and Pvt. Kevin Davis of Dexter, Mo., left, worked to clear trees in New Orleans on Wednesday, Sept. 14, 2005. (AP Photo/Ann Heisenfelt)
Casey Lucas, 7, left, and her mother Jennifer Lucas of Biloxi, Miss. reunite with "Hook" after finding him at the Forrest County Multi Purpose Center animal shelter Wednesday Sept. 20, 2005 in Hattiesburg, Miss., where animals were evacuated from the gulf coast area damaged by Hurricane Katrina. (AP Photo/Steve Coleman)
Two dogs that are among pets rescued from Hurricane Katrina are seen through a van window at Teterboro Airport in Teterboro, N.J., Thursday, Sept. 22, 2005, where they were delivered by charter plane. The 93 cats and dogs will be given foster homes by the North Shore Animal League America organization in Port Washington, N.Y., until they are claimed via the Internet by their owners or ar adopted. (AP Photo/Mike Derer)
SPCA volunteer Anna Strates, of Rockville, Md., calls for help from her partner after rescuing a kitten from the rafters of a wrecked home in the flooded Ninth Ward of New Orleans Wednesday, Sept. 28, 2005. Teams of volunteers have been scouring the city in an attempt to rescue the hundreds of animals left behind when Hurricane Katrina hit New Orleans a month ago. (AP Photo/Charlie Riedel)
Animal rescuer Suzanne Keeys, from Cary, N.C, carries a cat down from an attic as Mark Messenger, from Orlando, Fla., watches in New Orleans, La., Sunday, Oct. 9, 2005. Animal rescuers continue to collect and care for animals abandoned and suffering in Hurricane Katrina's aftermath. (AP Photo/Don Ryan)
NEW ORLEANS - SEPTEMBER 10: A dog stands on top of an air conditioning unit waiting to be rescued by Arkansans for Animals Inc in the Eastover neighborhood of New Orleans September 10, 2005 in New Orleans, Louisiana. Volunteers have found thousands of pets ranging from dogs and cats to pigs and goats and are taking them to temporary shelters near New Orleans to be cleaned and fed. (Photo by Lawrence Jenkins/Getty Images)
NEW ORLEANS - SEPTEMBER 10: Members of Arkansans for Animals Inc. unload a boat of exotic birds that they rescued from a home the Lake Forest Estates neighborhood September 10, 2005 in New Orleans, Louisiana. Volunteers have found thousands of pets ranging from dogs and cats to pigs and goats and are taking them to temporary shelters near New Orleans to be cleaned and fed. (Photo by Lawrence Jenkins/Getty Images)
NEW ORLEANS - MAY 30: Robin Beaulieu tends to homeless dogs at Animal Rescue New Orleans headquarters May 30, 2007 in New Orleans, Louisiana. The grass-roots group shelters animals that were left behind following Hurricane Katrina or have been separated from their owners. According to the LA/SPCA about 104,000 pets were left behind after the storm and 88,700 pets are still unaccounted for. (Photo by Mario Tama/Getty Images)
NEW ORLEANS - MAY 30: Robin Beaulieu tends to homeless cats at Animal Rescue New Orleans headquarters May 30, 2007 in New Orleans, Louisiana. The grass-roots group shelters animals that were left behind following Hurricane Katrina or have been separated from their owners. According to the LA/SPCA about 104,000 pets were left behind after the storm and 88,700 pets are still unaccounted for. (Photo by Mario Tama/Getty Images)
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Thanks to major strides made since 2005, the United States is unlikely to see another disaster affect pets the way Katrina did.
By fall of 2006, President George W. Bush signed the Pets Evacuation and Transportation Standards (PETS) Act into law, making certain that FEMA included plans to help individuals with household pets and service animals in the wake of a catastrophe.
The relationship between all of the animal welfare organizations that banned together has now been formalized.
"Prior to Hurricane Katrina, we were notorious for working independently. We weren't real keen on coming together. Katrina forced us to come together. There was just no way we were going to be able to manage that individually," Dr. Green said.
Dr. Green credits the delegation of authority from the ASPCA and Humane Society of the United States (HSUS) with setting up temporary shelters.
"It brought everyone under that umbrella," he said.
About six months after Katrina, the National Animal Rescue and Sheltering Coalition (NARSC) was formed, which includes shelters across the country, PetSmart charity, federal organizations, the American Red Cross and more.
"It is just so cool to see how far we have gotten," Dr. Green said looking out at the NARSC bootcamp and seeing individuals wearing 10 different organization shirts mingling. "We have put our differences aside."
Infographic shows statistics on pet ownership during Katrina: For more 10th anniversary Hurricane Katrina coverage, click here.