Q. I love your articles. I wished I lived close enough to bring my horse to you for work (if you even do farrier work anymore since you now teach.) In any case I have a question for you. My horse is kept in a stall next to a horse that has been diagnosed with hoof wall disease. I do not know what this is? Is it something that is contagious or just something a horse gets from being in a wet stall or poor diet? How can you spot if your horse has it? And, how do you treat it?

A. Hello Kari Ann,

Thank you for the kind words. I still love to shoe and have a few clients whose horses require a little more than just ordinary shoeings.

I assume that you are referring to White Line Disease. There is another condition of the foot called Yeast infection.

White line disease is a term used to describe a separation of the inner zone of the hoof wall.

There are three layers of hoof wall. The stratum tectorium is the smooth, shiny surface of the hoof that you can see. The stratum medium is the bulk of the hoof and the stratum tectorium is what we call the white line. From the bottom of the foot it is where the sole and the hoof wall join.

The separation occurs at the junction between the stratum medium and the stratum lamellatum (white line). The term White Line Disease is really a misnomer. The stratum medium is the area of concern.

The basic problem is separation between the hoof wall and sole at the white line. The separated area can spread vertically toward the heel or toe. It may involve any part of the wall from the toe to the heel. At first, separation of the wall does not cause lameness because it involves only the insensitive tissues. But lameness can occur if the dirt and other material that pack into the crevice results in a hoof wall abscess. Lameness can also occur when there is sufficient disintegration of the stratum medium so that the coffin bone can be rotated downward by the pull of the deep digital flexor tendon.

Causes of white line disease belong to the "Cause of the Week Club." You will see articles that have anecdotal evidence of everything from processed feed to paste wormers. The contents of the hoof wall separation have been cultured and the fungus and bacteria that are found are common in barnyards. Some feel that the bacteria are causative and others feel that the bacteria are opportunistic. None of these 'causes' can be verified clinically. The specific cause is still unknown.

Hoof problems that cause mechanical stresses on the hoof wall seem to have connection to white line disease. Horses whose hooves are out of balance, excessive toe length, collapsed underrun heels, club feet or chronic founder, to name a few, have tearing of the hoof wall at the white line. The mechanical breakdown of the white line allows bacteria to enter.

Treatment will vary depending upon your vet and/or farrier. If they feel that the bacteria are causative, then they will remove the diseased hoof, treat with an antiseptic and then wait until healthy foot grows down. If the diseased hoof is close to the coronary band the lay up time may be 10 to 12 months. If they believe, as I do, that the bacteria is opportunistic then the diseased hoof will be removed and the wall reconstructed with acrylics or polyurethane so the horse can get back to work in a couple of days.

Yeast infection is common only in wet, hot and humid conditions. The stratum tectorium, the outside wall we see, will have very poor quality. The hoof wall will appear similar to a piece of plywood after a winter of rain, falling apart. Because a yeast infection of the hoof is caused by environmental concerns it is difficult to treat, requiring constant attention from the owner.

You can relax, neither White Line Disease or Yeast infection are contagious. White line Disease does not appear to be diet related although there is some speculation that it may be an immune system response, but again this is purely speculation not backed by any scientific data.

The horse owner easily sees yeast infection of the hoof. White Line Disease, however, is more difficult for the horse owner to detect. A horseshoe covers the white line. Therefore the white line is only visible during the shoe process. On a bare foot horse there may be some white line separation but no disease process.

A well trained, professional farrier can spot White Line disease early on and, working with a vet, can resolve this problem for you and your horse.