The Bryant dogs were dropped off on Saturday afternoon by the family baby sitter. Their stay cost $75 per dog for 24 hours, Ms. Bryant said.

At breakfast with friends on Sunday morning, she said, she got a call from a manager. “She said Peanut had stopped breathing and was in the emergency room and the I.C.U., and they were working on her,” Ms. Bryant said.

She loaded Thaddeus into the car. “I was driving like a madwoman back to the city,” she said.

Along the way, there were more phone calls, including one with the manager of Biscuits and Bath who told her to assume that Peanut was dead. Ms. Bryant said she and Thaddeus began to pray aloud.

The company said its management was not available to discuss Peanut.

It turns out that on Sunday morning, Sweetie and Peanut were being brought back to TriBeCa from the Biscuits and Bath place on West 13th Street, where they had spent the night. The dogs were leashed by “slip collars,” also known as choke collars, which tighten when the dog pulls. Then their leashes were hooked onto the walls of the van. Other dogs were picked up.

“Some of the other dogs were anxious and active in the back, and managed to get tangled with the patient,” according to a report from Fifth Avenue Veterinary Specialists. “When the driver turned around, he saw the patient hanging by his choke collar. The pet was noted to not be breathing. The driver said he attempted chest compressions and nose to mouth breathing.”

Fifth Avenue Veterinary has 21 vets, and all the major specialties; it appears that since the closing of St. Vincent’s Hospital in Greenwich Village, a poodle there could have more immediate care in a medical crisis than a person. Peanut was intubated and given medicine to try restarting her heart, but it was over before she got there.