When the officer approached the horse, its head was hanging low and was struggling to stay upright, SPCA chief executive Andrea Midgen said.
The veterinarian attempted to walk the horse away from the edge of the estuary where he was located, however the horse could only manage a few feet.
The veterinarian found that the condition of the horse was caused by a combination of missing teeth and oral pain, due to sharp edges on the teeth ulcerating the gums. This resulted in a decrease in food intake over several months. The horse was also suffering from parasite infestation.
The veterinarian went on to say that the oral pain, inability to eat, emaciation and severe dehydration indicated that the horse would not have survived more than a week.
Due to the extent of his injuries and the extreme level of pain and distress he was suffering, the veterinarian recommended that the horse be euthanised on humane grounds.
The defendant declined to be formally interviewed but when asked what he thought about the condition of the horse, he told the inspector he was going to call a pet food company to come and get the horse but he "didn't get time".
The judge yesterday sentenced Tuaupiki to three months' community detention and ordered to pay reparations of $1,192.50 and $200 towards legal costs.
He was also disqualified from owning and exercising authority over horses for seven years.
Midgen said she was shocked how Tuaupiki treated the horse.
"This beautiful animal spent his final few months in great pain and distress because his owner failed to look after him properly.
"It is shocking to see the lack of care some owners give their animals. This horse died a completely unnecessary death, simply because his owner did not provide him with basic treatment.
"Our animals are completely dependent on their owners for food, shelter, companionship, and treatment if they get injured or fall ill. If you own an animal, it is your responsibility to provide these fundamental things."