In another abuse case, a nine-year-old Yorkshire terrier suspected to have been brutally beaten died on Monday night, about a week after an operation to remove 18 skull fragments.

Officers are still searching for the boyfriend of the pet owner's mother in connection with the case.

The Veterinary Specialty Hospital in Ho Man Tin reported to police yesterday that a woman brought in the Maltese on May 1 and that it died the next day.

Police have sought details from clinic staff and will contact the owner.

The Yorkshire terrier passed away on Monday after staying at a Mong Kok clinic for six days.

The dog was sent to the clinic run by the Non-Profit Making Veterinary Services Society after it was found unconscious in a Tsuen Wan flat.

Surgery was performed after it was diagnosed with depressed skull fracture. Veterinarians removed a total of 18 fragments in its skull.

The dog remained in a critical condition after the operation.

"Honey's condition improved on Friday. It was able to eat fluid food and swallow on its own. However, miracles did not happen," said the society in a Facebook post on Monday. Its condition deteriorated rapidly on Monday morning. Honey died.

"We hope Honey will rest in peace, but how could animals enjoy peace in a society where animal cruelty is so common?" the post read.

"We all have to reflect on why such a tragedy has happened."

The 44-year-old female owner of the Yorkshire terrier had asked her mother and elder sister to look after her dog at their Tsuen Wan home, which her mother's boyfriend occasionally visited.

The mother traveled to Thailand on April 30, and the elder sister left for work on May 1, leaving the dog alone with the mother's boyfriend.

The elder sister returned home and found the unconscious dog covered in injuries in the flat. The man had gone.

Under the Prevention of Cruelty to Animals Ordinance, offenders are liable to a fine of HK$200,000 and to imprisonment for three years.