Sandcracks
click on images for detail

Incidence

Many of the photographs on this page were taken from the feet of cows in one Swedish herd. (click image)

The incidence of the condition is very low in dairy cows (0.2%).

On the Canadian prairies the overall incidence is about 17% of mature cows while, in seriously affected herds, as many as 59% of the cows will have sandcracks.

Description

Some cows with sandcracks experience so much pain that they lose condition and are culled for that reason alone.

Stress associated with pain can cause breeding problems.

A sandcrack (vertical fissure) is a vertical split or crack in the claw wall. For convenience they have been classified into five types.

Many sandcracks are associated with horizontal grooves. It has been determined that the formation of grooves is associated with a change in the quality of feed intake.

Owners of purebred herds that have a high incidence of sandcracks are concerned that the presence of the condition will affect sales.

The nutritional changes causing sandcracks take place during the first lactation when a heifer is at pasture.

The condition affects mostly the outside front claw. The reason for this is unknown.

The Type-One Sandcrack

This type involves mainly the coronary band. It can be assumed that some sandcracks start in this region. (click image)

This type can only be identified in 5% of cases.

The Type-Two Sandcrack

The coronary band is involved but in this case the crack extends down to a horizontal groove or the middle of the claw.

This may indicate that the formation of grooves is an important part of the cause of a sandcrack. (click image)

The Type-Three Sandcrack

These are the most commonly seen cracks . They involve the entire dorsal surface of the claw from the coronary band to the apex. (click image)

The Type Four-Sandcrack

These cracks run from the centre of the claw to the bearing surface. (click image)

This suggests a sandcrack can resolve itself if the nutritional "insult" is not repeated.

The Type-Five Sandcrack

The type-five sandcrack starts in the middle of the dorsal surface of the claw. It appears to be a disturbance associated with bending.

Perhaps the claw horn has been weakened to make it susceptible to mechanical stress. Many of the lesions appear to be "explosive." (click image)

Causes

Body Weight

We found that cows with sandcracks were significantly heavier than unaffected animals. For example, the mean body weight in mature cows (cows greater than or equal to three years of age) with sandcracks was 611.0 kg compared to those without sandcracks whose mean body weight was 597.3 kg.

These findings agreed with those of workers in Alberta, Canada (Westra 1981, Goonewardene and Hand 1995). These workers hypothesized that heavier animals may place a greater load on the claws, thus causing sandcracks.

The commercial implications of weight versus size (volume) are several. It is believed that heavy cows produce calves that are heavier at weaning than those of lighter cows. It has yet to be determined if sandcracks make this hypothesis false.

Long Claws Bend and Crack

When a cow walks, there is an upwards pressure beneath the toe.

This creates a mechanical stress on the front of the claw rather like a human shoe which tends to bend at the instep. In the case of the claw, it also may bend (buckle) or even crack.

It is quite common to find vertical cracks apparently originating from a horizontal crack. If vertical and horizontal cracks are interdependent, it suggests that the cause of grooves could also be the cause of sandcracks.

The importance of grooves is worthy of your further study. I believe that they may be THE most important factor causing sandcracks.

Changes in Pasture and Between Forage and Pasture

Winter forage is rich in effective fibre and poor in protein. When beef cows are turned out to grass in the spring, there is a sudden increase in protein and drop in the quality of fibre as well as other changes in the nutrient quality of the grass.

Similar changes can occur at other times during the grazing season as the result of changing weather conditions, irrigation of pasture and rotational grazing.

As the result of careful investigation, we have found that sudden changes in the nutrition of beef cows probably cause the development of a groove.

Click image for more information.

A groove can be the focus of a sandcrack.

The Possible Role of Micronutrients

However, on most of the pastures grazed by cows affected by sandcracks we have found marginal levels of copper or zinc and sometimes high levels of iron or sulfate in the drinking water. The most prevalent micronutrient deficit in the diet of beef cows is probably vitamin E.

It is not known for sure if micronutrients play any role in the production of sandcracks.

However, it would be wise to collect data about the availability of trace elements on farms where claw problems exist.

Treatment

Treating sandcracks is possible but not cost-effective. It may be worth treating extremely valuable and/or show cattle.

It takes almost a full year for a treated crack to grow out.

However, remember that unless you introduce effective control measures the condition is almost certain to recur. The procedure is expensive and should be undertaken by a veterinarian.

(click image) above to see how a sandcrack can be treated.

Control

Thoroughly review pasture management (See also the section on pasture.)

• Avoid turning out cows for the first time in the spring when the grass is lush (i.e., between three and six inches high).
• Leave long cover on a pasture in fall and graze first in the spring. Avoid including legumes in pasture to be grazed first in the spring.
• Avoid fertilizing pasture to be grazed first in the spring.
• Offer good forage during first ten days after turn out.
• Ensure that micronutrients are balanced (See also the section on micronutrients.)
• We have found that cows fed Biotin are 2.5 times less likely to develop a sandcrack. This is not a magic bullet; you must also correct pasture management. Heifers should be fed this product.
• Test the water supply for iron and sulfates.
• Consider supplementing with zinc methionine. Evaluate the copper levels in the pasture.

Monitor Body Weight

We know for certain that heavy animals are more likely to have sandcracks. Therefore, the risk of this condition appearing is greater if you overcondition your animals.

Genetic Selection

This is a subject that needs more research. I am certain there is a link between claw volume and body weight. The appropriate balance between the two is not known.