Hidden Traits are a perk given out to those who purchase a Forever Pro account. They cannot be obtained in any other way, and do not transfer with the horse if you sell a horse out of your barn.
Hidden traits will show you each of the following for your horse: Prime, Colt Composure or Filly Power, Courage, Risk, Dirt %, Turf %, Favorite Distance, Mud Tolerance, Athleticism, and Pace Preference. These will appear in a table at the bottom of a horse's main page. Only YOU can see your horse's hidden traits.
Prime is the stat that determines how long a horse will remain at their peak. Each star equals roughly three months of prime. No horse may have more than thirty months' worth of prime at a time.
This relates to how well a colt will perform in an open race, where fillies may be present. The higher the stars, the more composed they will be, and therefore the better they will perform. This can be improved by early gelding of yearlings.
This relates to how well a filly will perform in an open race, where colts/geldings may be present. The higher the stars, the better they will perform. This trait could be particularly useful to throw off male competition in a big race, by using Colt Composure against them.
The higher the risk, the more likely your horse is to be injured. Risk can be lowered by the use of Wraps, or feeding Defend.
Dirt % & Turf %
Both of these bars show how well trained on a particular surface your horse is. When a horse is fully trained on a Surface, it avoids Race Notes such as "Dull Effort".
This is the Distance your horse likes to race on, and will do best on. Your horse will receive bonus points towards it's PR when racing on it's favorite distance. This is also useful when your horse doesn't have a particular range of distances based on it's genes.
This trait is how well your horse will race in muddy conditions. This will be shown as either Low, Average, or High. The use of Goggles can increase your horse's mud tolerance and this is particularly useful if it's raining at the track on the day of a big race.
Athleticism determines how much energy each race uses, and also plays a part in condition levels. You can give your horse an Athleticism boost from Low by using a pair of Blazing Horsehoes - this will take Athleticism up to Average.
Your horse will either show Fast, Slow or No Preference on this trait. On occasion, it may be in your best interest to race your horse at a style other than the one that uses their highest stat. In general, if the difference between their highest stats and their preferred style is less than 3, you may want to run them in the style opposite to their pace preference, to try to force the pace of the race into the one they prefer. If a race has a bunch of closers in it, it will have a slow pace. If it has many frontrunners/midpack racers, it may end up being a fast-paced race. Generally speaking, there will be far more slow-paced races than fast-paced ones, since it takes quite a few frontrunners/midpack to create a fast pace