Q: I recently noticed something strange about my mare’s hooves—there’s a red line that runs around the perimeter of each sole. This line is noticeable on all of her feet. After a trim, the line is still red. She is sound, but I worry that this might mean there’s something wrong.
A: The red lines on your mare’s hooves are evidence of a nutritional change, concussion or fever that occurred in her life last year. Your photograph shows that the red color is in the hoof wall, outside the white line.
This red in the wall originated at the coronary band, where the hoof wall is generated. The white line, which is a part of the hoof’s basic anatomy, is the strip where the bottom edge of the hoof wall meets the sole. Because the hoof wall grows at the rate of a quarter to 3/8 inches (about 1 cm) per month, the new wall reaches the bottom of the toe and becomes visible after 10 or 12 months.
Indicators of laminitis
On the other hand, if red coloration appeared in the sole—on the inside of the white line—then it would indicate a mild case of laminitis or road founder had occurred.
Your mare has probably long since recovered from the stress, severe concussion or whatever disruption triggered the coronary band inflammation responsible for the discoloration of her hoof walls and, as you stated, she is not now lame. At the time of the inciting event, she may have been off for a few days.
The results of these incidents are more visible in feet that are white. Eventually the red will disappear as the wall continues to grow out, just like bruises in our fingernails eventually disappear as they grow out.
Doug Butler, PhD, CJF, FWCF
Butler Professional Horseshoeing School