Many Texans grabbed not only their valuables but also their dogs, cats, birds and other pets as they fled the flooding caused by Tropical Storm Harvey.
"It seems like everyone coming off a boat is carrying a dog or cat," said Monica Schmidt, a manager for the Houston Humane Society.
After Hurricane Katrina in 2005, rescue officials have stressed the importance of evacuees bringing their pets because in New Orleans some people refused to leave for fear of abandoning their animals. Authorities had to include pets in federal guidelines for disaster planning, according to the American Society for the Prevention of Cruelty to Animals.
But on Sunday night that caused confusion and anger outside Houston's convention center, which has become a large shelter.
Dozens of people with dogs arrived only to be told they could not bring them inside or that animal services were not available to care for their pets. That included Rosana Nagera, 27, who took shifts with her husband in the rain with their shivering dog.
On Monday morning pets were welcomed in a designated area at the facility, where dogs nestled next to owners on cots. Red Cross officials said evacuees with pets are welcome at its shelters, and animals are typically housed in cages on site or accommodated by partner organizations.
Houston's BARC Animal Shelter on Monday set up a trailer to help house displaced pets at one site that wasn't allowing pets inside, it said on its Facebook page.
As authorities grappled with a growing number of residents arriving at shelters with pets, the storm continued to threaten thousands of other animals.
Animal rescue groups, many unable to reach affected areas because of flooding and blocked roads, said it would take days before the full toll emerged.
During Katrina, an estimated 250,000 dogs and cats were displaced or died, according to the ASPCA.
"We'll find that there are many losses after the waters recede," Jennifer Williams, president of the Bluebonnet Equine Humane Society in Texas, said Monday of the Houston flooding.
"I'm seeing stories on Facebook of stranded horses, and horses being pulled out of flooded stalls," she added.
Hundreds of animals in shelters from Corpus Christi to La Porte, Texas, were evacuated ahead of the storm, some sent as far away as Atlanta.
The Humane Society in Houston's 300-animal shelter will transfer existing animals to other locations after waters recede so it can take in an expected surge in stray animals, officials said.
The national Humane Society on Monday dispatched a rescue team to hard-hit Texas City.
"They're getting so many calls for animal rescue and response," said Katie Jarl, Texas state director for the Humane Society of the United States. "It's people who stayed behind with their animals, people who left them and now want someone to check on them, and reports of animals chained in backyards."
On social media and television, the plight of animals was shared widely, including a story about a man carrying two puppies in a cooler over high water and an abandoned dog found tied to a pole surrounded by water that was later rescued.
At the Houston Zoo, located near a medical center that was evacuated, some animal enclosure moats were filled with water but animals were all inside and safe, officials said. A crew of 30 people remained at the zoo to ensure the safety of its 6,000 animals.