Animal welfare inspector Talia Jenkins. Photo / Stephen Parker
The slugs have shattered bone and caused extensive internal trauma to the pets.
Jenkins said the cat shot in the head was lucky to survive, but still needed specialist care.
"The bullet entered the cat's head just above his right eyebrow, the cat is incredibly lucky to have kept his eye. There was a lot of bruising and swelling from the injury and the cat had to remain at the vets on fluids."
The SPCA does not yet have valid leads of inquiry.
"The police are aware of the case. Someone in the small community of Mamaku must know something. We urge that person to come forward."
Animal welfare inspector Talia Jenkins. Photo / Stephen Parker
Mamaku Residents and Ratepayers' Group spokeswoman Wendy Roe said the behaviour was unacceptable.
"Someone's walking round with a gun and that's a concern for anyone in the community whether they're a pet owner or not."
Mamaku resident June Farndon was distraught when her pet Sox was shot in November.
June Farndon is mourning the loss of her cat Sox, who was shot near her house. Photo / File
"Sometimes the littlest feet leave the biggest footprints in your life," she said at the time.
June Farndon, mourning the loss of her cat Sox. Photo / File
Farndon described the shootings as a "criminal act and sadistic, unwarranted violence".
"He was not a nuisance cat or a wandering cat. He was known and loved in the area... There'll be no more pet cats for me. I can't go through this again."
Another, Booboo, was also shot and dumped in the village in September.
At age 10, he learned to do high fives and sit on request.
"He was really friendly, very cuddly, was quite vocal. He would talk a lot," owner Belinda Walker said last year.
Belinda Walker after her cat Booboo was shot and dumped in Mamaku. Photo / File
She also raised concerns about gun use in a residential area, and the dangers to people, especially children.
"Obviously something is really terribly wrong with them [the culprit]."
Belinda Walker after her cat Booboo was shot and dumped in Mamaku. Photo / File
The SPCA said Mamaku cat owners should take extra steps to keep their "fur babies" safe.
These included keeping them inside where possible, keeping them to routine and ensuring they were home at mealtimes, checking them regularly for injuries, even very small holes which can be caused by slug guns.
If you have information: - Contact the Rotorua inspectorate on 07 349 2955 - All information will be treated confidentially