Koper Equine

The autonomic nervous system (ANS), affects bone. The ANS is divided into two branches: the sympathetic and parasympathetic systems, each with distinct effects on bone tissue.

1. Sympathetic System’s Role in Bone

• The sympathetic nervous system (SNS) is responsible for the body’s “fight or flight” response, which prepares the body for action in stressful situations. It generally increases heart rate, redirects blood flow to muscles, and releases energy stores.
• In the context of bone, the SNS innervates (penetrates) bone tissue more extensively than the parasympathetic system. This means the SNS has more influence over bone tissue, reaching deeper and affecting a wider area.
• Sympathetic activation of bone tissues, often linked to stress responses, leads to the suppression of bone growth. This occurs because:
• The SNS releases norepinephrine, a neurotransmitter that can inhibit osteoblasts, the cells responsible for bone formation.
• Chronic sympathetic activation (due to prolonged stress, for example) may reduce the bone’s ability to produce new tissue, leading to slower bone growth or even bone loss over time.

2. Parasympathetic System’s Role

• The parasympathetic nervous system (PNS) is responsible for “rest and digest” functions, promoting relaxation, digestion, and recovery.
• Unlike the SNS, the PNS has limited penetration into bone tissue. Its influence on bones is less direct and less extensive.
• Since the PNS generally promotes rest and recovery, it supports bone growth and healing by allowing the body to shift resources toward tissue repair, including bone regeneration.

Why Sympathetic Activation Suppresses Bone Growth

• When the SNS is active, the body prioritizes energy for immediate survival tasks, like fighting or fleeing, over long-term processes such as bone growth and repair.
• Chronic stress or ongoing activation of the SNS (e.g., due to constant physical or emotional stress) can lead to an imbalance where bone resorption (breakdown) outpaces bone formation, increasing the risk of weaker bones or osteoarthritis.

The sympathetic nervous system has a more complex and widespread presence in bone tissue compared to the parasympathetic system, and its activation, especially during stress, suppresses bone growth by inhibiting the activity of bone-forming cells (osteoblasts).

This means that long term (chronic) stress can negatively affect bone growth and maintenance in your horse, potentially affecting their health and soundness.