Frith Mitchell, 44, from Musselburgh, pleaded guilty to causing Tiga unnecessary suffering by failing to provide a suitable diet.
He also failed to seek veterinary treatment.
He was sentenced at Edinburgh Sheriff Court earlier this week.
Highlighting the case, Stephanie McCrossan, of the Scottish SPCA, said, "Tiga was in a very poor skeletal condition, he was dragging his leg, which was protruding at an awkward angle, across the floor as he walked and it was clear he was in urgent need of veterinary treatment.
"After taking Tiga to the vet we found out that he had several health issues which would have caused him to suffer unnecessarily for a prolonged period of time due to his owner failing to seek the necessary veterinary treatment he clearly required.
"Unfortunately the vet made the decision to put him to sleep due to the severity of his conditions.
"We are pleased that Mitchell has been dealt with by the courts and hope he will give serious consideration to his ability to care for animals in the future."
An East Lothian man who caused his cat unnecessary suffering has been given a community payback order of 85 hours unpaid work and has been disqualified from owning any animal for 10 years.