Sandcracks are vertical fissures or cracks in the wall of the claw. They account for ~0.2% of lesions of the claws of dairy cows. In western Canada, the average incidence in mature beef cows is ~20%. In individual herds, the incidence can be as high as 60%. No breed differences have been recorded. The lesion is extremely unsightly, which can be a considerable drawback for beef cattle producers who wish to sell their animals.
Vertical fissures occur almost exclusively in the lateral fore claw. In dairy cows, fissures are usually small and confined to the proximity of the coronary band. In beef cattle, they are more extensive, mostly starting at the coronary band and/or running part or all of the way to the bearing surface. In herds with the highest incidence of this disorder, lesions are also observed to start from a horizontal groove in the middle of the claw.
The etiology remains uncertain. The incidence is highest in mature, heavy cows. Bending or buckling of the claw around one or several horizontal grooves probably creates mechanical stresses that cause rupture of the claw wall.
In beef cattle in the prairies, it is theorized that the most probable cause is a rapid change from a winter diet low in protein and high in fiber to one high in protein and low in fiber.
Most sandcracks are not painful and require no treatment. However, if the origin of the lameness can be traced to a claw in which a sandcrack is present, routine treatment of the crack is appropriate.
A crack at the coronary band can split open, allowing infectious organisms to enter. The protrusion of granulation tissue through such a lesion can be quite troublesome. The dorsal pouch of the distal interphalangeal joint is extremely superficial at this point. The joint is very vulnerable, and lesions at this location should never be ignored. Superficial horn should be pared away and an astringent dressing applied (50% mixture of a sulfa powder and anhydrous copper sulfate). Pressure should be applied using cotton batten held tightly in place by a narrow, adhesive elastic bandage encircling the entire coronary band.
The fissures often have ragged edges that may be twisted and gape open. Sometimes, the edges move and pick up a foreign body. Cosmetic treatment may be requested in the case of show animals. The axial wall at the tip of the claw should be cut back so that the weight is borne only by the abaxial portion of the wall. The ragged edges of the fissure should be trimmed, ideally with the cutting disk of a grinding tool. In selected cases, a fissure can be immobilized with an application of methyl methacrylate after the two edges of the fissure have been laced together with steel wire.