DOG lover Maggie Trevelyan-Hall is warning all pet lovers in Marlborough to keep a close watch on their animals after one of her five dogs nearly died from suspected poisoning.

Vets bills for treatment including blood transfusions for ten- year-old black Labrador, Jock, have mounted up to about £1,000 during the last month since he was taken ill at home in Barnfield in Marlborough.

Only now, after four weeks of intensive veterinary treatment, can the family be sure that Jock has recovered although, said Mrs Trevelyan-Hall, it has left him with a weak heart and thyroid failure, both of which will require medication for the rest of his life.

Mrs Trevelyan-Hall said vets at the Elms Veterinary Surgery at Faringdon, where the family used to live, were convinced that Jock was the victim of rat poison.

The only place she can think of where Jock could have picked up the poison was outside the Thames Water sewerage works in Elcot Lane. Mrs Trevelyan-Hall said she had spoken with a Thames Water officer who confirmed that contractors employed to maintain their sites did use poison to control rats.

Mrs Trevelyan-Hall said: "Maybe a rat was able to leave a trail of the poison in some way and Jock picked it up on his paws and later licked them getting the poison into his system."

Jock who comes from the Queen's Sandringham strain of Labradors, became ill at the end of October. He could hardly walk and was short of breath.

The Elms veterinary practice discovered that the red-cell count in his blood was a quarter of what it should have been and kept him in to give him a blood transfusion.

Mrs Trevelyan-Hall said the dog was given huge doses of vitamin K to counteract the suspected poisoning.

She added that the family had no proof of where the poison came from and was not seeking compensation. "All we can do is warn other pet owners that there could be poison around and to act quickly if their dogs or cats fall ill suddenly."

A spokesman for Thames Water said that if rat poison was put down at any of its sites its use would be stringently controlled and he thought it unlikely that rats could carry traces of it out into publicly used areas.

He said contractors did use rat bait at the Marlborough sewage works. "There is baiting on the site and we do check this regularly to ascertain if any has been taken by rats. We have had no 'takes' in the last three months so there is no way that poison could have been carried off the site in anyway," he said.