Fears have emerged that a dog poisoner who killed three pets in Brent maybe have moved on to Hampstead Heath after five animals were taken ill this week.

The pets, who were with a professional dog walker, were rushed to a veterinary practice where they received emergency treatment for suspected poisoning on Tuesday.

All were said to be showing signs of poisoning including abnormal behaviour and severe lethargy but are now “doing well”.

Adam Mugford, who is head of emergency and critical care at Village Vet, wrote on Facebook: “The dogs show signs of poisoning with mainly neurological symptoms, signs of abnormal behaviour, loss of control of blood pressure and severe lethargy. Symptoms show rapidly.

“All animals under care are doing well and the cause is still unknown, but we have sent samples to the US for further investigation. More blood tests to be performed later. We will keep you updated.”

Last month, Lesley Hastings of Glenwood Grove, Kingsbury, lost her six-year-old Lurcher called Toby after he ate poultry laced with rat poison at the corner of Salmon Street and Fryent Way, Kingsbury.

Two other dogs who were walked in the area also died from poisoning.

Miss Hastings, who has two other dogs, told the Times: “Whatever their motive is they are a malicious person.

“They are killing dogs that are part of people’s families. To lose a dog like Toby like this is so sad.”

Sergeant Peter Rowntree from Brent Police, investigating officer, said: “This is such a nasty, cruel act which has killed three beloved dogs and endangered all domestic pets and wild animals, in such close proximity to a country park.

“This is not simple, ignorant mischief, but criminal activity and the persons found to be responsible will be prosecuted.”

Anyone with information about the cases in Hampstead should call Heath Constabulary on 020 8340 5260, or call Sgt Rowntree on 020 8733 3804 if you have information about the cases in Brent.

For further information about the latest cases click here.