When the intruder saw the black dog racing toward him, teeth bared, he ran out the door, jumped the fence and disappeared.
"He saved my life," Clark said.
But ever since then Charlie had been nervous of people. He became anxious and started eating household objects when Clark was not home.
A couple of weeks ago Charlie became sick. On Monday he started vomiting and developed diarrhoea and on Tuesday he started defecating blood.
X-rays and scans found a blockage in his intestine.
Papanui Pet Doctors vet nurse Aime Bruce said bits of towel were blocking his intestines, and were removed.
They believed they had removed it all and expected he would fully recover, she said.
But Clark, who can only work part time because of serious organ problems she has been dealing with for the past 14 years, is struggling to afford Charlie's treatment.
She believed the vet bill would come to about $5000 all up. She has used her savings, sold some of her jewellery and borrowed money from family but has still come up short.
The vet is willing to let her pay off the debt but she is appealing for help on Givealittle so she can at least make a decent deposit on it.
Clark said the dog was given to her as a gift when she seriously ill in hospital a few years ago.
"Charlie came into my life when I thought I couldn't survive my severe injuries any longer. When the treatment was excruciatingly painful he was always there for cuddles and helped me through," she said. "He is my child, my family and my best friend."
Clark said she would be lost without Charlie.
"Having him around really helped me with that guy breaking into my house and being sick. He's my support. Losing him, I couldn't have survived that."
Click here to make a donation towards Charlie's vet bill.
