The cat was forfeited to the SPCA after being taken for urgent medical attention for a large open wound, approximately 10cm by 10cm.
The wound may have started as an abscess from a smaller injury, possibly a cat bite.
Robust admitted noticing her cat had a small wound in January, which over time had increased to the size of a palm, but said she had struggled to find time to take it to the vet.
The veterinarian said treatment should have been sought as soon as the wound was noticed to reduce further infection, contamination, fever, and healing times, and to minimise pain and discomfort in the initial stages after the skin sloughed off.
"This case clearly demonstrates what can happen if you put your pet's health in the 'too hard' basket," said SPCA boss Ric Odom.
"Through her neglect the defendant has inflicted significant pain and suffering on her pet cat, all of which could have been avoided if she had simply taken the time to visit her local vet.
"If you own an animal, its welfare is your responsibility. If you fail to take care of it and we get involved, you could end up in court and lose your animal. If you think something is wrong with your pet, take it to the vet right away."
The cat underwent surgery, a course of antibiotics, and extensive rehabilitation.
It has since made a full recovery and will now be put up for adoption by SPCA Waikato.