What do you think the first readers learned from reading Black Beauty?

First readers of Anna Sewell's Black Beauty probably attained new perceptions of horses and, at least, some compassion for animals as well as learning of the dangers of intemperance.

Ms. Sewell wrote her one novel with the main purpose of informing readers of the mistreatment of horses specifically, and other animals in general. In the nineteenth century when this novel was written, horses were treated like machines to be used to do work that men were unable to do, and to transport people. For the upper class, having fashionable horses was de rigeur, so matched pairs were purchased and horses who had high stepping trots were popular. A very cruel device, the bearing rein, was used to force horses to keep their heads up at all times as it held the horse's head and neck in a sort of elevated hyperflexion. This bearing rein, then, could cause dangerous strain on a horse's back if it needed to go up hill as it pulled a carriage because of the unnatural position in which it was placed. For, a horse must be able to move its head and neck in order to pull heavy weights or absorb the strain of going uphill.

In addition to pointing out the cruelty of the bearing rein, Anna Sewell writes of many other cases of mistreatment such as in an episode Chapter 29 in which she tells of townspeople who rarely use a horse and buggy:

They always seemed to think that a horse was something like a steam engine, only smaller....they think that if only they pay for it, a horse is bound to go just as far and just as fast and with just as heavy a load as they please.

One driver is described as racing along and until it side-swipes a carriage. This collision causes the poor horse to have his flesh torn open with the blood streaming down. 

In addition to the promotion of animal rights, Anna Sewell, who was raised  as a Quaker in the Victorian Age, describes some of the dangers and repercussions of drunkenness. For instance, the groom who is responsible for Beauty’s knees being damaged is inebriated when he causes the accident. Frequently also, those who are described mistreating horses are in a state of drunkenness.

Certainly, animal rights and moral, upright behavior are help up to the readers as standards in Anna Sewell's didactic novel, Black Beauty.