The inspector noticed the man was sweating profusely and had blood on his chin and cheek. When asked what had happened, he said: "I didn't beat my dog that much."
He went on to say that his dog had been fighting with another dog so he had given it a good hit.
Inside the caravan, the inspector found a female pit bull-type dog cowering in the corner. She had a cut to her forehead, blood running down her nose and swelling above the right eye and beneath the jaw.
The dog appeared to be very frightened and had her legs and tail tucked up under her.
When the inspector commented on this to the man, he said: "So she should."
A vet found the dog had a puncture wound between the eyes, bleeding from both nostrils, bleeding within her right eye, bruising and swelling around her left hind leg, swollen eyes and ears, bloody diarrhoea and bloody urine.
The vet found the most likely explanation for her injuries was excessive blunt force trauma, rather than dog fight injuries.
SPCA chief executive Ric Odom said the abuse was a "horrific case of violence against a defenceless animal".
"We're pleased that the court has handed down a reasonably tough sentence in this case due to the violent nature of the offending and the defendant's lack of remorse. We hope this sends a strong message to the community that it's not ok to beat your animals under any circumstances."
Animal mistreatment should be reported to the police or the SPCA immediately, he said.