Police horses have and are still used as an intimidating tactic at protests and peaceful protests at that. The use of police horses are unnecessary and bring the animal into harms way. Not only this, people feel threatened by their presence and are more likely to act in violent ways when police horses are commanded to charge or walk near people. As seen in many recent videos of horses being brutally attacked by the public. 

When you factor in all the expenses for training, feeding, stabling, and outfitting, funding a single police horse is decidedly expensive. And horse units, usually deployed at large public events, perform poorly on typical accountability metrics like arrest rates. With so many more cost effective alternatives, there is no need to bring these innocent animals into the firing line. The money used to train these horses could be used for further training for police officers in handling situations without excessive force or violence and also to enforce higher regulation within the police.