George Smith, 48, snuck into the creature’s stable block where he was discovered by its owner.
She had grown suspicious when she earlier saw Smith loitering nearby before returning to find him stood on a crate behind Ruby, nine, with his trousers behind his ankles.
Cops then found 10 soiled nappies, women’s underpants, and a teddy bear at the static caravan when he lived.
Smith, who himself owns two horses, was handed a four week prison term, suspended for 12 months, and banned from contact with animals for 10 years, after pleading guilty to sexual penetration of a living animal.
In a victim impact statement read out at Leicester Magistrates Court today the owner, who cannot be named for legal reasons, said “This incident has deeply disturbed me.
“My 10-year-old daughter is scared of going to the yard now as she knows George has been arrested.
“She is scared George will turn up to the stables and we will be in danger.
“Looking back I now find it really strange he said how I could not sell Ruby as ‘she is my mate’.
“George looks at Ruby as some kind of partner or girlfriend. He seems fixated on her while I doubt he even knows my other horses’ names.”
Describing the events on March 10 Sally Bedford, prosecuting, told the court the owner had been “shocked” to discover Smith having sex with her horse at the stables in Hinckley, Leicester.
His previous suspicious behaviour led her to return to the stables after she spotted him lurking in his Land Rover after locking up on March 10.
She found Smith having sex with the mare. Her partner grabbed Smith and they called the police.
She said: “The owner became suspicious of the defendant due to his previous behaviour.
“In 2016 she was with her daughter and found Smith leaving the horse’s stable with his shirt lifted up and closing the zip on his trousers.
“On another occasion the defendant told her he had seen someone else interfering with her horse.”
Mrs Bedford told the court investigators took swabs from the horse’s vagina which matched Mr Smith’s DNA.
Defending, Rashpal Singh said Smith had owned up to the offence immediately and that he was prepared to sell his two horses as soon as possible through a third party.
Following his early guilty plea, Smith was handed a four-week jail term suspended for 12 months.
He was also given 120 hours community work and ordered to pay £200 in costs.
Smith was banned from all non-incidental contact with animals for 10 years, and is subject to a restraining order preventing him from contacting Ruby’s owners or buying nappies.
Carl Stroud write this news and you can keep up with thesun