"His head was cut off, but his collar was still on his neck. I was shocked and upset. I couldn't believe it - I don't understand why someone would do this."
Mrs Gedye has spoken to her neighbours and has appealed for information on Facebook.
"But no-one seems to know anything. I'd like to know who did this so they can be stopped. Gruff is a big, strong goat, so it would have taken more than one person to kill him."
In the three years Mrs Gedye has lived at Mangamahu, this is the second attack on one of her animals. Not long after she moved there, one of her dogs was locked in a shed with its legs broken. The dog survived.
She believes the two attacks are unlikely to be related.
Mrs Gedye has reported the attack on Gruff to the police, but was told those responsible were unlikely to be found. She said police told her there had been several incidents recently in Mangamahu of animals being deliberately injured or killed.
"I'm worried about my other animals, but there's not much I can do other than check on them every day."
+If you have information please contact Mrs Gedye at pamelajoy9@hotmail.com.