Five of the dogs were seized and taken to the SPCA for veterinary treatment.
Putt Putt was in significant pain, and had to have its left hind leg amputated.
The SPCA vet said the dog had likely suffered a traumatic foot injury and then chewed off its own foot, which would have been missing for several days before it was discovered.
SPCA Auckland executive director Bob Kerridge said any lay person would have known the dog was in need of urgent veterinary attention.
"The kennels clearly fell well below the minimum standards set out in the Animal Welfare Code of Welfare for dogs. All the dogs were put at risk of damage to their respiration and gastrointestinal systems due to the faecal, algal, and bacterial hazards in the kennels where they were confined for long periods of time.
"This is a case of neglect, pure and simple. As a result 'Putt Putt' has now lost one of her hind legs, which permanently limits her mobility. The original injury should have treated immediately but there is a wider pattern of neglect here. It is obviously completely wrong to confine dogs in such appalling conditions and ignore their obvious distress, let alone dogs with serious injuries."
Smurthwaite was also convicted of five charges of ill-treating animals in 2007.
Mr Kerridge said tougher sentences should be imposed as a deterrent to further offending.
