Six guinea pigs have been found thrown in bushes by the Halfway, St Sampson.
The GSPCA were called out at around 6pm on Monday 18 March.
Welfare Manager Lorna Chadwick says the animals had been poorly treated.
"Given how they were found, it is obvious that someone took the effort to throw the animals up into the branches, it's hard to comprehend why someone would do that.
The guinea pigs were very underweight and showed signs of long term neglect so we are very concerned that there more awaiting the same fate, and we need to find them."
The Guernsey animal charity took photographs of the scene and collected the dead bodies.
Manager Steve Byrne says it is rare to find animals abandoned in this way in Guernsey.
"This is a situation we take extremely seriously. We do deal with causes for concern almost on a daily basis that we go out and investigate, but to actually have pet animals left that have died in a public place is something that we have not seen in recent years.
It is very difficult to know why this could have happened to have six pet animals left in a public place is extremely unusual and we are appealing for information.
If any member of the public does know anything or saw anything in the Halfway area, please do call us."
Anyone with information can contact the GSPCA on 01481 257261.
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