One of the dog owners, Stanley, said he took his Shiba Inu Mung Mung to the dog garden at the park in January. His friend, Ko, also took his Border Collie Matea to the park and the two dogs had a good time there.

Ko said both Matea and Mung Mung enjoyed sniffing the grass and jumping into the bushes. The two played for an hour.

However, the healthy dogs fell sick hours after leaving the park.

"Mung Mung showed signs of epilepsy and her legs were shaking. Her head then began to cramp on one side and she was forced to lie down," Stanley said.

"I didn't know what to do and I could only help her open her mouth as I was worried Mung Mung would bite her tongue."

Stanley said Mung Mung tried to open her eyes and look at him whenever he called her "good girl," but the dog was unconscious when Stanley got her to a veterinary clinic.

"Only 15 minutes after being sent to the clinic, the vet told me they couldn't save Mung Mung," he said. Then Stanley received news from Ko that Matea had developed the same symptoms and was put down.

"I never thought something like this would happen to Matea. she was like a daughter to me," Ko said.

Ko and Stanley visited the dog garden next day to search for evidence and found chocolate and meat sticks.

The two dog owners have reported the case to the police but said it would be hard to carry out investigations as there are no surveillance cameras at the park.

But vets told the two owners that their dogs were likely poisoned by tetramine -- an active component of a rat poison.

"The vet told me the poison was highly toxic," Stanley said. "I don't understand why someone so sick would poison a dog."

Veterinarian Reanne Kwok told Sing Tao Probe that the poison was not easy to find.

"The rat poison containing tetramine has been banned around the world and the person who did this must have obtained the drug through illegal means," Kwok said.

"The poison will affect dogs' central nervous system and dogs can experience seizures, diarrhea, vomiting and even stop breathing immediately," she said.

The Agriculture, Fisheries and Conservation Department has collected samples from the two dogs and is still waiting for the result.

There are over 110 pet-friendly parks set up by the Leisure and Cultural Services Department. The Chui Yu Road Rest Garden was opened in February 2021 for residents and pets.