The aftermath of the neglect at Spindles Farm.
The 12-week trial ended with James John Gray, 45, and his son James Gray junior, 16, being found guilty of causing unnecessary suffering to 40 horses.
Along with wife Julie, 41, and daughters Jodie, 26, and Cordelia, 20, they were also found guilty of failing to meet the welfare needs of 114 horses.
The investigation was one of the biggest in the British RSPCA's history, and just providing care and rehabilitation treatment for the horses has so far cost the organisation more than £850,000.
Bicester Magistrates Court heard how the family was prosecuted after RSPCA inspectors discovered more than 100 horses, ponies and donkeys, and the bodies of a further 32 equines at Spindle Farm near Amersham between Friday, January 4 and Wednesday January 9 last year.
Officers from World Horse Welfare, Redwings Horse Sanctuary, vets and Thames Valley Police worked alongside the RSPCA to rescue the surviving animals from what it described as a terrible scene.
The Grays denied all counts of cruelty and neglect. In court, James Gray claimed sole responsibility for the animals. He said he ran a limited company dealing in 2300 to 2400 equines a year and, of these, "nine or ten" would die.
In respect of James Gray and James Gray Junior, District Judge Andrew Vickers said in reaching the guilty verdict today: "They ought reasonably to have known that leaving the weak ones to go to the wall would cause suffering and it was easily preventable."
The family will be sentenced on June 12 at Aylesbury Magistrates' Court.
The animals remain the property of the Grays unless the court rules otherwise at sentencing.
This means the RSPCA cannot yet take enquiries on rehoming them.
It said any support given to its Amersham Horses Appeal would help to continue to feed and care for animals like these.
"The operation to remove the animals to safety over a year ago was a difficult but successful joint effort between many animal welfare agencies and the police," said RSPCA Inspector Kirsty Hampton..
"The RSPCA would like to thank them all - and in particular the Horse Trust, Redwings, and World Horse Welfare - for helping us provide ongoing care for the huge number of deprived horses, ponies and donkeys removed from Spindle Farm in January 2008."
The British Horse Society welcomed the guilty verdicts in the trial.
However, chief executive Graham Cory said they were scarcely a cause for celebration.
"We must remember that many horses and ponies suffered inexcusable cruelty at the hands of these people. But we are certainly pleased that they have at last been brought to justice.
"Now we must move on and treat the Amersham case as a spur to even greater efforts to tackle cases of equine neglect and abuse."