Two cases of a mystery illness that can kill dogs walked in woodland have been reported to a Norfolk vets after a break of several years.

Eastern Daily Press: Fritton Woods where a case of Seasonal Canine Illness has been reported Picture: Nick ButcherFritton Woods where a case of Seasonal Canine Illness has been reported Picture: Nick Butcher (Image: Archant © 2008)

Seasonal Canine Illness (SCI) can strike between August and November, and without prompt veterinary treatment can prove fatal.

Haven Vets in Great Yarmouth say they have seen two cases so far, prompting it to post a warning on its Facebook page and circulate posters.

The alarm was raised by Leanne DeJean, of Drifter's Way, Great Yarmouth, who walked her toy poodle Bella in Fritton Woods, also know as Waveney Forest, on Sunday.

By the early hours of Tuesday morning the animal was shaking and suffering with vomiting and diarrhoea, classic signs of SCI.

Eastern Daily Press: Fritton Woods where a case of Seasonal Canine Illness has been reported Picture: Nick ButcherFritton Woods where a case of Seasonal Canine Illness has been reported Picture: Nick Butcher (Image: Archant © 2008)

Having rushed the two-year-old to the vets she was put on a drip and remains in hospital where she was diagnosed with the mystery illness.

'I have been in absolute pieces, she is my little baby,' the 39-year-old said.

The surgery confirmed it has also seen another dog and that it was the first time in several years a case had been confirmed.

The cases have been reported to scientists from the Newmarket-based Animal Health Trust (AHT).

Symptoms usually appear within 24 to 72 hours of dogs walking in woodland in autumn, and can come on very quickly.

They include vomiting, diarrhoea and lethargy.

The AHT launched an investigation in 2010, after dogs became ill after being walked in wooded areas including Sandringham, Thetford Forest and Rendlesham.

Harvest mites have been linked to the disease but tests have not proved conclusive.

A spokesman for AHT said: 'We would never want to say to people 'do not go to the woods' because the percentage of dogs that get ill is small.

'Our advice would be to be as vigilant as possible and do not take any chances.

'We do not know what causes it but if you think there is something wrong with your dog just go to the vets, do not delay.

'It does come on so quickly but with treatment a lot of dogs do pull through.'