In sentencing, the worst cases where the "maximum" is given are to those offenders where the offences have aggravating factors.
For instance, if this person is convicted, he has long previous convictions for animal cruelty, it was a deliberate act because he enjoyed frying dogs, it was premeditated and pre planned and took place over a number of months, was committed on bail and he has shown no remorse yes a custodial sentence near the maximum - is almost certain.
On the other hand, if it was a mistake, where he popped into the nick to collect something, got say involved in helping to subdue a violent prisoner and it took longer than the 30 seconds he was intending to be. Plus he has no previous convictions and is probably hugely cut up about it (in my experience, police dog handlers are extremely close to their dogs) and as a result has lost his career. Plus he pleads guilty at the earliest opportunity, well frankly a maximum prison sentence would a) be manifestly excessive and b) likely to be over turned on appeal.
Those are just examples - I make it clear that I have no knowledge of the facts.
Aggravating and mitigating factors must be taken into account in every offence - it is part of our sentencing provisions and long may it continue.