The contaminated meat was discovered by a dog walker on the Cuckoo Trail in Hailsham on Wednesday.
The sausages, which had been sliced open and filled with the blue pellets, were handed in to police.
The RSPCA warned that dogs ingesting even small amounts of some substances could suffer kidney failure and die.
A spokesman said: "The RSPCA is deeply concerned about any spate of suspected poisonings, but especially one where evidence suggests it may be deliberate.
"Animals, and especially dogs, are often extremely curious and will be drawn to food.
"If anyone suspects that their dog has been poisoned they must take it to a vet immediately. If possible, they should take a sample of what the dog has eaten."
Poisoning is a criminal offence in the UK under the Animal Welfare Act 2006.
The maximum penalty for those found guilty is up to six months imprisonment and/or a fine of up to Â£20,000.

Darren McDonald, 40, travelled from Ballymena, County Antrim, to support his team.
At Glasgow Sheriff Court he admitting running on to the pitch after the final whistle and kicking the other man on the head or body.
McDonald was also given a three-and-a-half year football banning order.
He is currently serving a sentence in Northern Ireland and the latest jail term will begin after that ends.
McDonald was named and pictured in the media after the game that saw Hibs beat Rangers 3-2 on 21 May.
Footage from the match was played to the court and newspaper reports from the time were brought to the sheriff's attention.
McDonald was seen clearly wearing a pink T-shirt and had distinctive tattoos.
The unknown Hibs fan was on the pitch after the match and was on the ground, having been assaulted by someone else.
McDonald ran over to him and pulled his right leg back to kick him but slipped and fell backwards.
The court heard that the momentum meant his leg made accidental contact with the Hibs fan's head or body.
He then got up and ran off after the attack, leaving the Hibs fan on the ground.

Chief Rabbi Ephraim Mirvis said Mr Peres "was the greatest living example of an unshakable belief in the pursuit of peace against all odds".
Former British PM Tony Blair also paid tribute describing the Nobel Peace prize winner as "a political giant".
Mr Peres died aged 93 on Tuesday, two weeks after suffering a stroke.
He was one of the last of a generation of Israeli politicians present at the new nation's birth in 1948, serving twice as the country's prime minister and once as president.
He also won the Nobel Peace prize in 1994 for his role negotiating peace accords with the Palestinians a year earlier.
Rabbi Mirvis said Mr Peres "gave hope to millions of people" that a peace deal would be achievable.
He added: "Tragically, thus far, we have not succeeded. But from Shimon Peres we learned that we must never let go of that audacious commitment to peace, even when all around us are ready to do so."
He went on: "For those of us whom he inspired during his remarkable lifetime, we say: No matter what the future holds, your legacy lives on in the Jewish people who will never rest until we achieve our eternal dream of peace among the peoples of the world."
Mr Blair paid tribute to Mr Peres on twitter, writing: "Shimon Peres was a political giant, a statesman who will rank as one of the foremost of this era or any era, and someone I loved deeply".
Cocktail sausages believed to have been stuffed with toxic slug pellets have been found at a popular dog-walking spot in East Sussex.
[NEXT_CONCEPT]
A Rangers supporter who kicked a Hibs fan during a pitch invasion at last year's Scottish Cup Final has been jailed for nine months.
[NEXT_CONCEPT]
The chief rabbi of the UK and Commonwealth has paid tribute to former Israeli PM Shimon Peres, describing him as a "true giant amongst men".