"When he came home, it was actually quite caked over, so we think it might have happened about three or four hours earlier. The force behind it obviously stunned him for a while," Stuart said.
He was taken for treatment at Havelock North's Animal Care Vet Clinic the next day.
"Certainly if that pellet had gone through his eye, or other tissue, then at best he would have lost his eye, at worst it would have killed him," veterinarian Tracey Wallace said.
"He was lucky that part of the skull is reasonably thick and it hadn't penetrated through."
Wallace said it was "reasonably easy" to remove and only took about 20 minutes with general anaesthetic.
"Incidents like this are not uncommon," she said. "It is something we have always had a problem with."
"We see cats with slug pellets in them, unfortunately, reasonably frequently. Sometimes we find them by accident when we are X-raying them for other things and sometimes we find them maliciously."
"As vets we find it disappointing that people go to these lengths to potentially deter animals. The potential for harm is huge and it is unacceptable when it is someone's pet."
Stuart has reported it to both police and the SPCA, as well as distributed flyers around her neighbourhood and shared the incident on social media.
"It's quite disturbing that kind of thing happened on a residential street."
Abuse of cats has been centre of attention lately with another case of a cat being shot, as well as a number of pets dying from suspected antifreeze poisoning.
On November 2, 3-year-old cat, Molly was shot with a slug gun and had to have her leg amputated as a result.
Penalties for shooting a cat could include a jail sentence of up to five years, and a fine of up to $100,000.