Hoof balance is a cornerstone of equine podiatry, vital for the overall health and soundness of horses. Central to this concept is the alignment of the pedal bone (P3 )within the hoof capsule. When discussing hoof balance, terms like negative plantar angles (NPA) come into play, reflecting a crucial aspect of hoof balance and its impact on the horse’s well-being.
What is Hoof Balance?
Hoof balance encompasses the proportional relationship between the bones, soft tissues, and external structures of the equine foot. It ensures that weight distribution is optimal, minimizing stress on joints, tendons, and ligaments. Achieving and maintaining proper hoof balance is essential for preventing lameness and promoting longevity in performance horses.
Understanding Negative Plantar Angles (NPA)
Negative palmar or plantar angles of the pedal bone occur when the rear part of P3 sits lower than the front portion within the hoof capsule. This misalignment can lead to a cascade of issues affecting the entire limb.
Recognising NPA
Detecting NPA requires a keen eye and often involves assessing the relationship between the dorsal and palmar/plantar aspects of the hoof. Key indicators include:
- Sole depth under the tip (SDT) exceeding sole depth under the wing (SDW) of P3.
- Hyperextension of the distal interphalangeal (DIP) joint, bringing the extensor process of P3 closer to the dorsal articular margin of the second phalanx (P2).
- Dorsal slippage of P3, displacing it dorsally in relation to P2.
Grades of NPA
NPA can vary in severity, ranging from mild to severe. Floyd (2010) outlined grades from observations of negative palmar angles, which can be adapted to negative plantar angles:
- Grade 1: Mild misalignment with minimal distortion.
- Grade 2: Moderate misalignment with noticeable distortion and slight functional impairment.
- Grade 3: Severe misalignment with significant distortion and functional limitations.
Problems Caused by NPA
NPA disrupts normal biomechanics, leading to a range of issues:
- Poor hindlimb posture: NPA alters weight distribution, predisposing horses to weak or underdeveloped hindquarters, sacro-iliac inflammation, hamstring overloading and lower back problems.
- Poor front leg posture with NPA; overloading of navicular area, deep digital flexor and associated structures, coffin bone inflammation and bone bruising in the pedal and pastern bones are among the most common problems.
Proprioceptive deficits: Misalignment affects sensory input, compromising the horse’s ability to maintain balance and coordination.
Pain and lameness: Chronic NPA can cause discomfort, lameness, and reluctance to perform.
Relevance to Soft Tissue Structures
The implications of NPA extend beyond the skeletal system, impacting soft tissues such as the superficial and deep digital flexor tendons (SDFT, DDFT), and suspensory apparatus. Misalignment places undue stress on these structures, increasing the risk of strain, tears, and tendonitis.
Management and Correction
Addressing NPA requires a multifaceted approach, including:
- Regular farriery: Skilled trimming and shoeing to restore proper hoof balance.
- Rehabilitation exercises: Strengthening exercises to improve hindquarter musculature proprioception.
- Veterinary oversight: Monitoring and addressing any underlying issues contributing to NPA, such as conformational abnormalities or musculoskeletal imbalances.
- DSS actively supports the suspensory apparatus and by doing so contribute to improve NPA, degenerative suspensory desmitis and conformational issues and conformational issues in hindlimbs.
In conclusion, understanding negative plantar angles is crucial for maintaining equine soundness and performance. By recognizing the signs, addressing underlying issues, and implementing appropriate management strategies, we can mitigate the detrimental effects of NPA and promote the well-being of our equine companions.