White line disease collectively refers to a group of lesions affecting the junction between the sole and the wall of the claw. Lesions of the white line include hemorrhage (an escape of blood from a ruptured blood vessel), fissure (a long, narrow opening or line of breakage made by cracking or splitting), and abscessation (a collection of pus surrounded by a capsule), which represent different stages of the breakdown of the integrity of the white line. This condition can also be explained as the separation of the horn from the sensitive layer of the foot (lamina) characterised by filling up with debris. This puts pressure on the laminae, debris accumulation may cause an abscess at the coronary band (the soft skin that the horse’s hoof grows from. Just like the cuticles on our fingers,is the junction between hoof wall and hairline).
Source: Ishler et al. (1997)
The white line is the soft, white horn that joins the wall horn with the sole horn. It is produced by the laminae which means any disturbance to the laminae, such as bruising, will produce even weaker horn. As the white line joins the hard capsule of wall horn with the relatively flexible sole horn, it has to withstand considerable tensions. These tensions are increased by/with turning and pushing behavior on hard surfaces, or sharp, stony penetrations from the environment. Wet conditions can soften the horn and increase the risk. The main factors thought to contribute to white line lesions include:
- Rumen acidosis and other dietary imbalances leading to poor horn quality
- Physical trauma producing bruised white line horn
- Shearing forces across the white line, such as twisting and turning on an unyielding surfaces
- Loose stone and uneven surfaces that physically penetrate the white line
- White line disease is also a common finding in beef bulls which may result from a combination of poor feeding management and excessive loading of the rear legs. It can also affect other livestock too such as sheep, goats and even horses.
- Limping, difficulty in walking
- Painful lesion on hoofs possibly covered with debris, bleeding or pus filled.
- Abrasions on the hoofs with the white soft tissue visible
- Bruising and cracking of the hoof
When the white line lesion extends as far as the quick, a site of infection can become established, often resulting in an abscess if the drainage is blocked. Alternatively, a lower grade focus of inflammation or infection may be present, producing a mild lameness.
- Careful identification of the painful lesion
- Good drainage of any pus
- Removal of any loose or under-run horn (often1-2 weeks later) as well as any other debris.
- Relieve weight from the painful claw: The application of a lift to the sound claw is helpful, as is complete immobilization of the digit. Immobilization of the joint reduces the risk of permanent deformity due to avulsion (pulling or tearing away) of the deep flexor tendon.
Control and Prevention of white line lesions
Prevention of white line lesions involves reducing standing times and improving the diet, cow flow and under-foot surfaces.
- Claw trimming will help remove early lesions that haven’t progressed to the laminae.
- Supplementation needs to be maintained long-term and the beneficial effects will only be noticeable after approximately 130 days.
- Addition of 20mg per day of biotin to the ration daily and trace elements such as zinc, have been shown to reduce the risk of white line disease in older cows.
- Reduced lying behaviour, the increased risk of bruising and risk of twisting on concrete
FOR DAIRY FARMERS-Pushing in collecting yard-improve collecting yard design to ensure good flow; encourage cows into the parlour, never shout or drive cows; disarm the electric backing gate, taking up slack space with the backing gate and no more; avoid any aversive experiences.
Important Things to Know About White Line Disease (Summary)
- Hemorrhage, fissure and abscessation of the junction between the sole and the wall of the claw are collectively referred to as white line disease.
- Lesions typically occur in the outer claw of the rear foot—two thirds of the way back from the toe.
- Fissure and abscessation of the white line must be treated by removal of all loose wall horn and transfer of weight to the healthy claw.
- Prevention requires attention to feeding management, regular hoof-trimming, and provision of comfortable stalls and non-slip walking surfaces.