A VET from Potters Bar has warned dog owners to be vigilant against the killer parasite lungworm following a death in his surgery.

Purdy, a one-year-old Hungarian Visla, died two weeks ago at Village Vet, in Southgate Road, after contracting the disease.

Dogs often pick up the parasite after eating or touching slugs and snails, which act as intermediary hosts.

The disease is very hard to spot because of its wide-ranging symptoms, but it can often prove fatal.

Practice partner Russell Welsh said: "This parasite is becoming more and more prevalent as the climate becomes warmer and wetter and there are more slugs about. It is especially bad in summer.

"When dogs eat the slugs, the larvae migrate through their heart and into their lungs, and can cause multiple problems.

"But the signs are so varied and non-specific, it can often go undetected."

The Village Vet group, which has 16 veterinary practices in London, Hertfordshire and Cambridgeshire, has seen 16 cases of lungworm in the last year, four of which have been fatal.

The parasite is now so prevalent that nearly a quarter of vets across the UK have seen either confirmed or suspected cases of the infection - yet only six per cent of dog owners have heard of the disease.

Purdy's owner, Barbara Maton, 50, from Parkgate Crescent, Hadley Wood, said more public information should be made available to owners to prevent further deaths.

"I had never heard of lungworm when Purdy fell ill," she said. "But, now I have learnt that you can actually help protect against it, I feel so guilty.

"People need more warnings on how to protect and control their dogs. It's important that as many people know about it as possible.

"Purdy was such a special dog, such a character. It was a terrible shock."

Signs of lungworm include lameness, coughs, reluctance to exercise, depression, weight loss, fits, vomiting, diarrhoea and persistent bleeding from minor cuts, though none of these are proof of the parasite.

Purdy was taken to the vet after showing signs of lameness, but tests were inconclusive and she was put on anti-inflammatories.

A few days later Mrs Maton discovered her breathing rapidly and deeply, and a second consultation revealed several mouth ulcers and respiratory distress.

The dog was sent to the Royal Veterinary College, in South Mimms, where a faecal egg count revealed lungworm larvae, but she had a seizure and died before she could be saved.

There is currently no prevention for lungworm, but Mr Welsh said owners could take steps to protect their pets by stopping them eating garden grubs or touching other dogs and dog excrement.

"Owners need to realise that when their dog is nibbling at something, it may have lungworm," he said.

"They should pull the dog away immediately. If they have any concerns, they should bring the dog in for testing."