A family say they are devastated after their dog died following a visit to a stream which was later found to be contaminated.

Jasper, a golden retriever, became unwell with vomiting and diarrhoea hours after walking in Cut Throat Dene, Sunderland, his owner Gavin Heskett said.

An investigation by the Environment Agency into suspected pollution found a burst pipe had allowed wastewater to spill into the stream. It has since been repaired.

Northumbrian Water said it was "very sorry" to hear of the death and its "thoughts are with the owners", adding any claims it receives would be "fully investigated".

Roker Park Vets, which initially treated Jasper for sickness, said it had been dealing with a number of dogs falling ill after walking in the dene area in recent weeks.

"We're all devastated. He hadn't had his fourth birthday yet, it was tragic," Mr Heskett told the BBC.

"This [the dene] was the only place we walked, we never went anywhere else."

Mr Heskett had been on a routine walk to the dene with Jasper, but hours later the dog became lethargic, followed by vomiting and bloody diarrhoea.

Jasper was taken to the vets where they kept him in overnight, administered fluids and ran tests including for parvovirus which was negative.

However, he was referred to a pet hospital in Cramlington, Northumberland, for specialist care where all further efforts failed.

"We got the call… and they said 'if you want to say your goodbyes, you better come by now' and that was it," Mr Heskett said.

"Me, my wife, my son and daughter were all with him when he crossed rainbow bridge."

In total Mr Heskett received vet bill of about £9,000 and although the majority was covered on his insurance, there was a shortfall of £3,000.

Rory Thomson, practice owner at Roker Park Vets, said there had been an "increase in the number of dogs" with vomiting and diarrhoea where the severity "seemed more extreme" and, "rather than requiring a few injections, they were requiring hospitalisation".

He said: "We noticed at least two or three dogs associated with a recent walk in Cut Throat Dene.

"I'm aware of other practices with suspected cases that haven't been so favourable, like Jasper."

He added he had not yet been told if the area was safe for dogs to walk again and urged owners to avoid it where possible.

Malcolm Bond, Liberal Democrat councillor for Fulwell, said Northumbrian Water should provide compensation to owners whose "dogs have been killed or made ill".

"I also want to see regular testing of the water in the dene to reassure local people that this issue has been properly solved.

"After all, this stream also runs directly on to Seaburn beach."

The Labour-run Sunderland City Council said it was "also concerned" about water conditions in the dene, but had since "received assurances" from the Environment Agency after finding "no conclusive issues" with the water quality.

The Environment Agency said it could not confirm whether reports of animal illness were linked to the leakage, but "where appropriate, we will not hesitate to take enforcement action".

Northumbrian Water said it investigated after being made aware of the issue "and found the cause of the pollution to be a leak on a combined sewer a mile away".

"We fixed this straight away and it was resolved within 24 hours," a spokesperson said, adding it had not yet received any claims regarding deceased or unwell animals.