Clare Hopkins of Tukes Avenue, Gosport avoided jail after admitting three offences over the horses kept at Newgate Lane, Fareham.
The 44-year-old left three horses unattended for two weeks between April 19 and May 3 this year.
During those two weeks, a horse called Phoebe died, but was left with her stablemate Fred.
A pregnant horse, Molly, was so emaciated she was close to death, the RSPCA said.
RSPCA inspector Jenny Ride said: 'In my fifteen years as an RSPCA inspector this was the worst case I have ever seen. It was horrendous.
'To see a deceased horse basically rotting away and another horse, Molly, not long from death must have been mental, as well as physical torture, as horses are highly intelligent.
'In summing up it was clear that the judge understood the severity of the suffering endured by these three horses. She stated that this case involved the "dreadful treatment of the three animals" which involved a "period of starvation that was inexcusable".
'This was a very distressing case but I am pleased that Fred, Molly and her foal Bluebell, who was born in our care, have now been successfully rehomed to the same new home.'
Appearing at Portsmouth Magistrates' Court on Wednesday, Hopkins admitted causing unnecessary suffering to Phoebe, Fred and Molly by failing to adequately investigate and treat the causes of their poor bodily condition; failing to meet the needs of Fred and Molly by failing to provide them with adequate hoof care and failing to meet the needs of Fred and Molly by failing to provide a suitable environment.
District judge Anne Arnold handed Hopkins an eight-week prison sentence suspended for 12 months, twenty days of rehabilitation activities, a Â£300 fine and an order to repay the vet costs of Â£274.80.
She was also banned from keeping horses for three years.