Any serious illness with fever or metabolic consequences — colic, infections, influenza, or even a serious wound — can result in rings on the hoof. These conditions change the body’s demand/need for key vitamins, minerals and proteins/amino acids. If demand exceeds supply, available nutrients will go to the area/system that has the emergency need instead of to the feet.
Changes in blood supply to the feet also cause rings, which is what happens with founder/laminitis. However, it also occurs in horses that are undergoing rigorous training/exercise and possibly inflammation of the feet.
A rapid change in diet (such as a change in hay or grain or grazing on rapidly growing pastures) commonly shows up as a ring on the feet, representing the adjustment period to new feeds. You can tell whether it was a change for the better or not by looking at the hoof wall quality above and below the ring, as well as changes in rate of hoof growth.
Naturally occurring major metabolic changes also show up on the feet. The ring halfway down the hoof in the photo corresponds to this mare’s foaling six months before the photo was taken.
Growing horses may develop a ring if a period of heavy training is superimposed on a growth spurt, which results in serious competition for available nutrients. In fact, if your young horse is showing prominent rings it is a warning to have the adequacy of your diet evaluated.
Prove it to yourself. Look for a prominent ring on your horse’s feet. You can pinpoint it in time by remembering the visible hoof represents about 12 months of growth (with “average” trimming and wear); the halfway point is your record of what was going on six months ago. If you think back carefully you will come up with an explanation. It may be something as routine as spring or fall pastures coming in, change to a new brand of feed or addition of a supplement.
Horses being fed grain mixes that are not fixed formulas — those that will change the types and relative proportions of ingredients in the mix — may show many rings on their feet. Even vaccination or deworming may cause a ring. Illness, allergy, injury, pregnancy, weaning, drastic shoeing/trimming change could be the reason. Think back and you will find the reason.
