I agree to a point, DBF , but that would therefore imply stopping animals from being bred for work in general. Can dogs not be bred for hunting, or shepherding, and horses for riding schools (though not for racing I would happily have that banned).
We originally bred animals for work, not for domestic needs, so it would be tough to know where to draw the line.
From my work with former police horses they have always, without exception, been well trained, very healthy, friendly and good with people, and the vast majority used for crowd control and rarely injured on the job. And they really do help keep people under control (which is what policing boils down to).
However I may be wrong and may have been lucky to only ever have seen the exceptions.
Fully agree with long sentences for anyone hurting a police dog or horse (or, come to that, any animal at all, working or not).