Dog owners have been urged to be vigilant after a number of pets mysteriously died after using a popular walking spot.
Officials suspect the animals may have been poisoned but no-one knows if they were deliberately targeted or died by accident.
The deaths have left families in the village of Cross Hills, North Yorkshire, extremely anxious about their pets.
In almost all instances, the dogs collapsed and died within minutes of returning from a walk along a tree-lined footpath which leads down to fields by a lake.
The RSPCA has put the number of deaths at eight, although there could be more dog owners who have been affected but who have not come forward yet.
RSPCA spokeswoman Leanne Plumtree said: "We thought it was probably an isolated thing at first but then we heard about more and more dogs getting poisoned in the area.
"Not all of the dogs have been referred to the RSPCA. We have been working with two vets in the area who have confirmed the deaths.
"We are really concerned that people stay out of the area with their pets.
"This particular footpath seems to have been pinpointed in an area where a lot of dogs are walked. But we don't know for sure where they have picked this up from or what they have picked up."
Miss Plumtree said that the dogs had very quickly shown symptoms after being walked, convulsing and frothing at the mouth before dying.
She added: "It is obviously very distressing for the dog owners.
"They are extremely worried and until we can pinpoint what has caused this, dog owners are being told to stay away.
Vets are carrying out post-mortem examinations to try to pinpoint the exact cause of death.
Eileen Johnson's Jack Russell, Diesel, was one of the first dogs to die when he collapsed just ten minutes after returning home from a walk.
Mrs Johnson, 71, had put the kettle on after the walk when she heard a thump and turned around to see her six-year-old pet having a fit.
She told the Daily Mail: "We walk the fields five days a week and I can't believe this has happened.
"He was a lovely, lively little thing. He had never been ill and then he died so suddenly as if someone just came in and shot him in front of my eyes."