A green substance inserted into the sausage is believed to be rat or snail poison, which can be fatal to dogs.
Pet owners are being urged to beware after a dog became sick from eating food laced with poison at a popular park in Sydney's Inner West.
Steve Badgery's eight-year-old English cocker spaniel, William, ate a suspicious sausage left behind at Weekley Park in Stanmore.
It had a green substance inserted into it, believed to be rat or snail poison.
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"He loves food, very food driven," Badgery told 9News.
"I couldn't get it out of his mouth."
Badgery took his dog and a sample of the sausage to Sydney University Veterinary Teaching Hospital, whose staff helped get most of the poison out of his system.
Vets believe he ate up to six pellets of rat bait, which could have led to his death.
"These substances are highly toxic and can be life-threatening for dogs," Sydney University's Veterinary Teaching Hospital said in a statement.
Nearby residents took it upon themselves to conduct a search of the park for any more laced-sausages and found four more.
NSW Police, the Inner West Council and RSPCA have been notified.
Sydney University Veterinary Teaching Hospital is urging pet owners whose dogs have visited the park and eaten anything suspicious to contact their local vet immediately.
Parkgoers are advised to stay vigilant, keep their pet on a leash and prevent them from eating anything off the ground.
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