A South Auckland farmer has been fined thousands for locking his dogs in filthy kennels for so long that one of them chewed off its own injured foot.

The Auckland SPCA says Allan Smurthwaite was convicted on Monday for a range of charges relating to mistreating animals.

Inspectors found seven Australian cattle dogs and two border collie-type dogs all confined in kennels littered with a massive build-up of faeces. Food bowls were also infested with flies and drinking water green with algae.

A female cattle dog named Putt Putt had one left hind foot completely missing with flesh and bone protruding.

The 66-year-old has been sentenced to 150 hours of community service, disqualified from owning animals for 10 years and ordered to pay reparation of $7202.81.

The SPCA said it is not the first time Smurthwaite has ended up in court for abusing animals in his care and believes he should have been jailed.

SPCA Auckland director Bob Kerridge said Smurthwaite was convicted on similar charges of mistreating animals in 2007 and Monday's sentence is similar to that handed down then.

Mr Kerridge believed the sentence would make little or no difference to prevent Smurthwaite from reoffending.

He said judges have the option to provide tougher penalties such as jail sentences and larger fines, and should use them.