Mr Kerridge told Radio New Zealand's Morning Report programme this morning he stood by his comments.
"I think the figures speak for themselves," Mr Kerridge said.
"If you look at Manukau City and its make-up of population then obviously it is a very varied population - both immigrants and ethnic people.
"In terms of our own prosecutions for dog offences, a very, very large percentage of those are also ethnic and also from South Auckland.
"What we're saying is, this is a contributing factor, we're not making an issue of it."
Mr Kerridge highlighted Pacific Island groups and "other immigrants" as being partially responsible, but conceded that SPCA conviction figures did not record ethnicity.
"Socioeconomics is another contributing factor, there's not much we can do about that.
"We're not pointing the finger at anyone, we're just generalising and saying that it is a contributing factor.
"The bottom line is, education is required."
Mr Kerridge declined any suggestion that he was racist. "I haven't got a racist bone in my body."
A large contributing factor behind dog attacks was ignorance, Mr Kerridge said. "And therefore we need education."
Mr Kerridge added that he favoured licensing owners instead of registering individual dogs.