In one of the worst cases RSPCA investigators said they had seen, one severely malnourished horse had to be put down immediately and another was not expected to live. A further 10 horses were taken to one of the charity's rescue centres for urgent veterinary treatment.
Officers are making regular trips to the Millfield Farm, near Rusper, West Sussex, to feed and care for the remaining 90 horses, many of which were valuable bloodstock, which were also found starving in stables.
A spokeswoman for the RSPCA said: "The horses were in an extremely bad state. It appeared that no-one had been looking after the animals, and they had not been fed or watered for a long time."
Officers from the RSPCA made their discovery on January 2, and are considering prosecuting. The 23-acre farm is being run by former stable girl Penny Armstrong, who was Gucci's mistress until his death at 64 in 1995.
The farm also came under investigation in 1995, before Gucci's death, when his neighbours complained that some horses were so emaciated their ribcages "stuck out like toast racks" and that some animals had running sores and diseases.
Miss Armstrong, 27, who was not available for comment yesterday, has two children by the late millionaire designer. She and his former wife Jenny Gucci are fighting a legal battle over the contents of the estate and pounds 2.5 million mansion adjoining the farm.