The cat could have suffered for a week before it was found, she said.
She could not say when and where the leg-hold trap was set.
Leg-hold traps needed to be fixed to the ground, and any live capture trap must be checked within 12 hours of sunrise each day it remains set to determine if an animal had been caught, Ms Sweeting said.
"If this trap was done properly, whoever set the trap would have gone to check within 12 hours and if that was done the cat would not have found itself in this condition. The cat was not microchipped, it was not very friendly and was pretty thin when found.
"It's actually very fortunate it did not become tangled in the bush because if it had, it would have slowly starved to death," Ms Sweeting said.
"The message here is for people to make sure they educate themselves on the rules around setting traps. They just need to be responsible."
The SPCA has constantly reminded people not to set up leg-hold traps in urban areas because of the risks to pets and children.
The latest warning comes after a Wairarapa man was last week fined after he admitted nailing a leg hole trap to a fence to catch possums.
A 4-year-old cat was discovered dead, hanging from the trap by the left front leg about three days later on March 23, 2016.
Under the Animal Welfare (Leg Hold Traps) Order 2007, the use of leg-hold traps within 150m of a dwelling without permission of the occupier or in any area where there is a probable risk of catching a companion animal is prohibited.