"Over the weekend we've seen a very small weight gain. While it might appear to be progress, we would have expected greater improvement than we've seen.
SPCA staff have given the dog the name "Bright Eyes".
"We're doing everything we can but it is touch and go. There is a very high likelihood this dog won't make it.
"We are completing further veterinary tests, to try and establish whether there are any reasons why we are not seeing the level of progress that we would hope."
Ms Kalin said the abuse was "absolutely shocking".
"There has been a period of neglect. This is not neglect that occurs over a week, there has been weeks of neglect.
"How someone can look at that dog in the face and not do anything is our greatest concern. The degree of cruelty in this case is one of the worst cases we've seen. And the degree of cruelty cannot go unpunished."
Ms Kalin said the box the dog was found in has been sent away for forensic testing, but as the box was wet it is not known whether any evidence can be gained as to who was responsible.
"We haven't been able to secure any information from the public. We urge if anyone knows anything to come forward.
"This person must be stopped. They must be held accountable."
If you have information on this case, or any other incidents of animal abuse, contact the SPCA on 09 256 7300.
- HERALD ONLINE