An unknown disease has killed 12 dogs in the New Forest and is spreading to other parts of the country.
The illness, which causes kidney failure and leg sores, has struck 14 dogs with only two surviving.
Hampshire-based vet Anderson Moores says on its website: "A number of dogs that had been walked in and around the New Forest developed acute kidney failure between December 2012 and March 2013. Six patients were seen by Anderson Moores Veterinary Specialists over this time period.
"An additional eight cases were identified that were considered to be suffering from the same disorder. Two of these additional eight cases were from the New Forest (Dibden and Verely car park) and the others were from Worcestershire, Cornwall, County Durham and Surrey.
"Two of the six dogs seen at Anderson Moores Veterinary Specialists survived. Unfortunately none of the other dogs survived despite intensive treatment."
Blood, urine and faeces have been examined, as well as on post mortem tissue and water tested in the New Forest, but the cause remains a mystery.
The Forestry Commission says: "The reported cases represent an extremely small proportion of the many hundreds of dogs that are exercised in the New Forest every day and it is likely that this syndrome is extremely rare."
Speaking to the Daily Express, Louise Beal, 52, who lost her spaniel Bruno to the mystery disease after walking him in Latchmore Brook in the New Forest, said: "It hasn't killed any cattle or other animals that we know about but it took a week to kill Bruno. It is seriously dangerous.
"I couldn't bear to go through that again, it was awful. We don't walk there anymore. It's such a shame because we love the forest but until we know what we are dealing with, we cannot risk it."
Walkers and tourists warned over 'deadly toxin' killing dogs in New Forest
Dog put on wrong flight ends up in Ireland