Dave Palmer-Davies and Pendle.
The book features Pendle the police horse - a foal who goes on a journey of discovery to decide what he wants to be when he grows up.
All royalties from sales will go towards the Lancashire Police Horse Benevolent Fund, which helps ease the county's retired police horses into their retirement.
"The possibility to also raise money for retired police horses gave me the push to do it," Palmer-Davies said.
The Lancashire Police Horse Benevolent Fund was set up in 2010 to support retired police horses. Once retired, horses are given to a new owner and the fund helps to cover any ongoing costs including vet treatment which may be needed.
Pendle is a real-life police horse for Lancashire Constabulary. He is an 18-year-old bay gelding. Most police horses retire at around the age of 20 and he is likely to be the next police horse to retire from the force.
"I have no previous experience of writing books but I had always wanted to write one for my little boys.
"I really enjoyed writing the book and my career as a mounted police officer gave me lots of creative ideas for the story. I have shown my children the book and they think it is fantastic.
"All money raised from the sale of the book will go towards the benevolent fund, which helps to ensure a smooth transition for our horses to their new owners once they have retired. The support available from this fund is invaluable.
"I hope people will support this book and this important charity to help the horses that spend their working life protecting the county's residents."
The book has been published by Pegasus Elliot Mackenzie Publishers Ltd under its children's section Nightingale and can be pre-ordered now.