Two brothers allowed their Labrador dog to put on too much weight causing it unnecessary suffering, the RSPCA has told a Cambridgeshire court.
Derek Benton, 62, and his brother David, 53, failed to stop the dog's weight soaring to more than 11 stone, Ely magistrates heard.
Vets said nine-year-old Rusty was so fat he looked like a walrus.
The brothers, from Fordham, are on trial over a charge of causing unnecessary suffering.
The court was told the brothers had ignored a vet's advice on the dog's health.
Stephen Climie, prosecuting on behalf of the RSPCA, said Rusty was "hugely and grossly" overweight when seen by the RSPCA in February.
"The dog could not walk a few steps before having to sit," said Mr Climie. "He certainly collapsed if he was kept standing."
Mr Climie said the dog, which had a long-standing hip complaint, also suffered pain in its joints and had difficulty breathing.
Rusty has now lost three and half stones under RSPCA care.
The trial, thought to be only the second prosecution of its kind in the UK, continues.