JAXX, a five-year-old Dalmatian, was Cate Lilley’s best friend.

She had found him through a rescue centre when Jaxx was a puppy and the pair had been inseparable ever since.

So when Mrs Lilley needed to go away for a week, she chose a kennels boasting more than 30 years’ experience, owned by the local parish council chairman.

She dropped Jaxx off at the kennels in April last year, confident the dog was in safe hands. She never saw him again. When she came to collect him, she was told the dog had bolted in a storm and vanished.

Mrs Lilley scoured the West Sussex countryside for seven weeks. But it was only after a newspaper appeal that a motorist came forward and said he had knocked Jaxx down outside Wolstonbury Kennels on a main road in the village of Bolney in West Sussex.

The driver’s account puzzled Mrs Lilley. Not only did he say he had run over Jaxx a day or two after she had left her pet, but also that he had gone to the kennels for help. He even recalled the dog being lifted into a van with “Wolstonbury” written on it. Wolstonbury Kennels deny this version of events. Its owner, Tony Steer, has been arrested.

Mrs Lilley, who hired an agency, The Pet Detective, to investigate, has accused the kennels of misleading her. “We feel we were lied to and deceived. It has caused such a lot of heartache,” claimed Mrs Lilley, 37, a company administrator.

Mrs Lilley, from Partridge Green, West Sussex, left Jaxx at the kennels on April 26 last year before flying to Jersey where her fiancé, now her husband, Stefan was working. On May 3, she returned and was told the dog had run off.

That evening, Mr Steer, phoned Mrs Lilley and “was very apologetic”. Her hunt began. “On several occasions, I would go out at four in the morning because that is a time when dogs can be out looking for food,” she said. On June 23, the motorist called and, in a witness statement to the private investigator, said he had hit the dog in the road at the entrance to the kennels.

The driver said: “I could see the dog was seriously hurt because it wasn’t moving and was panting very heavily as if gasping for breath.” He asked the kennels for help. A man appeared and went to the bottom of the drive in a van.

“He and I were able to lift the dog into the rear of the van and place it on the floor,” the motorist said. “As we did this, the dog died.”

In a letter to Mrs Lilley sent last year, Mr Steer said that when Jaxx went missing, he had been visiting his wife and mother in hospital, but his house sitters were “adamant that nothing happened”.

“If Jaxx had been hit by a car I would have told you… I gain nothing by lying.” Mr Steer told The Sunday Telegraph: “Unfortunately I had house sitters at the time. I cannot help you I am afraid.”

A spokeswoman for West Sussex police said the force, the RSPCA and Mid Sussex District Council were investigating. “A 45-year-old man from Bolney has been arrested on suspicion of theft and bailed pending further inquiries,” she said.