According to Olive Press sources, detectives have found ‘toxic substances’ at San Pedro’s Eucalyptus Park, as well as Parque la Futura, in Marbella’s La Campana area.
Police closed off both parks after poison was discovered by children’s swings and climbing frames.
Some dogs have perished within minutes of coming into contact with the substance and even sniffing it can cause death within an hour.
A vet last night told the Olive Press that he had seen ‘quite a number of poisoning cases in just a few days’.
The spokesman for Urvet pet hospital, in Marbella, said: “It is a very serious as mostly the pets are being poisoned in play parks.
“It seems to be the same produce and is sometimes hidden inside sausages, or something similar but in 10 or 15 minutes they are dead.
“Imagine if a child ate that. We would be looking at murder.”
The incidents, which could number up to 20 so far, are mostly taking place around the La Campana area of Marbella.
However, one victim, a British expat, who asked not to be named, said his Yorkshire Terrier had died just 15 minutes after eating something around the Bello Horizonte area, the other side of Marbella, on Sunday.
The owner, a businessman, said: “I’m devastated. I rushed him to the hospital after he began having convulsions. It was only a few minutes after we got home.
“He was trying to be sick to get it out and was acting aggressively. We knew something was wrong.
“This is a very sick stunt. I hope the police catch them fast.
“My vet told me there had seen five or six similar cases in the last week alone.”
Another British expat has stressed that the poison is not just in the parks, as his two-year-old beagle Ruby was poisoned in the streets near Pointers Vets on Avenida de la Girasoles in Nueva Andalucia on Sunday night.
“She has only just come out of the vets,” Phil Rawlings, 37, told the Olive Press this morning, “She has serious neurological damage and is very poorly.
“I must stress this isn’t just in parks as she was only in the street and luckily it happened to be by our vet so she was saved but she is still seriously ill.”
Parents are being warned to be extra vigilant of their children playing in parks, while the Guardia Civil’s Seprona arm is probing the case.
The dogs become disorientated and symptoms include foaming at the mouth, diarrhea and vomiting.
“It appears to be two types of poison and both are like rat poison, so once the dog tastes it or even sniffs it they have convulsions,” another source told the Olive Press.
“If you should know anyone that has a dog die because of the poison, it’s very important that they report it to the police because the police need denuncias otherwise nothing will be done.”