Growth rings are the horizontal lines that you see that go all the way around the hoof. These occur due to changes in feed, environment, and/or stress. Where these don't necessarily cause a problem they can be signs of a problem. They can be associated with inflammation.
Wall bruising is generally not a cause for lameness. They are caused by trauma at the coronary band or at the level of the laminae. If it is from the laminae, inflammation can be the cause. I generally call this sub-clinical laminitis; meaning that there is no obvious pain or changes clinically that would warrent concern but it is a silent alarm that inflammation is occurring and needs to be addressed. Nutritional imbalances can also cause this bruising. Providing your horse with proper minerals can help both with growth rings and wall bruising. You will notice bruising in white hooves but it is just as prevalent in black hooves.
Abscesses can erupt from the coronet band. As they grow out there will be a horizontal crack. This is unslightly and can be minor but there can subsequent damage where the hoof wall connects to the laminae. There is usually nothing to do for this but let it grow out. As it comes to the end of the hoof wall extra care may need to be taken to roll the edges so the wall doesn't break.
Side bar: White hooves are not weaker than black hooves. There are minor differences but they are able to function and withstand the same.
Example: It is now spring and you can't wait to turn your horse out onto that beautiful grass pasture. You are busy so you don't really notice that he seemed stiff for a few weeks. Otherwise, summer was great and you rode but not on rocky areas as that bothered him or maybe he was just fine all summer. Now it is fall and your trimmer or farrier is there and you notice that he has growth rings that are an inch or so down from the coronet band. They say 'eh, don't worry about it, the horse is fine right?' WRONG. He may currently be just fine but those rings and the stiffness you didn't see was really a little case of laminitis that resolved on its own. But it is telling you that you should be more careful about pasture next spring. As this spring did a little damage, so will next spring. They hoof doesn't just grow that way. It is an intricate map that tells you a lot about what is going on. We all need to be tuned to our own 'horse maps' and we can learn a great deal.
