A closer look at the five main triggers that drive the need to apply hoof blocks.
By Dr. Dana Tomlinson, Research Nutritionist, Zinpro Corporation
Proper blocking is essential to the recovery of diseased, damaged or improperly trimmed claws. Summer and early fall are especially important times with respect to development of claw damage or Claw Horn Disruption (CHD) resulting in the need for pain relief through therapeutic blocking.
Heat stress, for example, often causes cows to increase standing time and can result in CHDs such as sole ulcer, white line disease and heel fracture. Heat abatement measures may also weaken claw horn, as time standing in manure, urine and water increase. Breakdown in horn integrity may accelerate claw wear, resulting in thin soles, as well as loss of heel horn and claw angle. The subsequent weight imbalance can cause sole hemorrhaging, sole ulcers, and painful lameness.
Another often overlooked factor is the increased frequency of parturition (calving) in late-summer and early-fall months. Unfortunately, painful lameness frequently occurs in early lactation (the first two through five months of lactation). Parturition often results in mobility of the pedal bone with potential damage to sole corium, especially if further complicated by extended standing time due to poor stall comfort, additional time in headlocks for health management, high stocking density and poor stockmanship.
Parturition is also closely associated with metabolic disorders such as hypocalcemia (milk fever) and hypoglycemia (ketosis), which often result in production of inferior claw horn. In addition, significant loss of body fat in early lactation may lead to loss of sole fat pad support, which results in sinking of the pedal bone with potential development of a sole ulcer.
When are hoof blocks needed?
There are five main triggers that drive the need to apply hoof blocks:
1. Heat stress, which contributes to CHD due to:
• extended standing time, sole concussion, corium damage and hemorrhage;
• excessive sole wear;
• increased claw hydration due to standing in water, manure and urine; and
• heel fracture from extended standing times.
2. Excessive sole wear caused by:
• long walking distances;
• poor flooring – broken, irregular or deteriorated walking surfaces;
• improperly finished or aggressively grooved flooring;
• walking up and down sloped walkways; and
• sand or other abrasive bedding materials.
3. Metabolic disorders, including milk fever, ketosis, SARA and systemic infections (reproductive or respiratory). These may cause CHD and repeated production of inferior horn with subsequent loss of pedal bone support, sole hemorrhage development, and greater potential for sole ulcer.
4. Infectious claw diseases may result in cows with significant imbalance or loss of sole horn (such as heel horn erosion) or cows that walk on their toes (such as digital dermatitis and foot rot).
5. Improper trimming. Toes trimmed too short, soles trimmed too thin, excess removal of sole horn at the toe, abaxial wall, or excess removal of heel horn (claw angle too shallow) may also require blocking.
Block application steps
Blocking shifts weight bearing within the claw to allow for recovery of damaged living tissue and claw horn. Since sole horn grows at approximately 5 mm (about 0.25 inch) per month, blocks should last at least four weeks or longer. Use the following proper block application steps to help ensure good results.
Dr. Tomlinson has a doctorate degree in animal science, ruminant nutrition and management from Virginia Polytechnic Institute and State University and is employed by Zinpro Corporation as a research nutritionist based in Virginia. Email him at Dtomlinson@Zinpro.com.