Horses
Horses in the west were more than just a vehicle, they were the difference between life and death for many. There is a reason crimes involving horses historically were punished very severly as stealing a person's horse was tantamount to trying to kill them or ruin their livelyhood.
Stables
There are stables all across the world, some run by NPC's and others run by cast members. NPC stables will charge a fee for homing a horse, and will provide the horse with average care during its stay. Characters will be able to give their horse additional attention to make sure they stay healthy and happy if they choose to put in the time. Horses that are stabled will only be accessible at the location they were stabled.
Calling The Horse
Unlike the base Red Dead gameplay, you will not be able to magically summon your horse to you, you will have to be within a reasonable distance of where you left them. Horses that are left in the wild will eventually be returned to the closest NPC stables.
Breeding
In order to provide more ways for players to have an impact on the world, each other and stand out there will be an in depth breeding system for horses and possibly cattle. Using a simplified genetic model every animal will have its own unique DNA that will have direct impact on the traits of the horse, from coat color and pattern to stamina and speed.
Nature vs. Nurture
Breeding and raising horses and cattle will not just be about the genetics and family lines. For the animals to reach their true potential their maximums and minimums will be effected by their environment growing up, including access to nutrient rich feed and medical care from vets. Beyond that it will take training and care to keep horses at their best, and their performance will diminish with neglect.