What is the recommended use and management of a thoracic sling in horses?

The Thoracic Sling in Horses: Anatomical Structure and Clinical Significance

Anatomical Definition

The thoracic sling (also called the thoracic girdle or synsarcosis) is the unique muscular suspension system that attaches the equine forelimb to the trunk, as horses lack a bony clavicular connection between the scapula and axial skeleton. This sling consists primarily of the serratus ventralis, pectoralis, and subclavius muscles that support the thorax between the forelimbs 1.

Clinical Relevance in Trauma

Pectoral and Axillary Injuries

• Trauma to the thoracic sling region represents an important cause of morbidity in horses, particularly involving pectoral and axillary lacerations 1
• Axillary wounds require close monitoring for respiratory distress until complete healing occurs, as these injuries can compromise the structural integrity of the thoracic sling and affect ventilation 2
• Horses with axillary wounds had concurrent pneumothorax in 80% of cases (12 of 15 horses) and subcutaneous emphysema in similar proportions, indicating the proximity of these structures to the pleural cavity 2

Emergency Management Priorities

• Initial management of thoracic sling trauma should include assurance of a patent airway and adequate ventilation, along with treatment for shock if present 1
• Tetanus prophylaxis must be instituted for any open wound in this region 1
• A thorough evaluation including the abdominal cavity should be performed, as penetrating wounds may extend beyond the thoracic region 2

Surgical Access Considerations

Thoracotomy Approaches

• Lateral intercostal thoracotomy can be performed in standing sedated horses with minimal perioperative complications, though this requires working around the thoracic sling musculature 3
• Right lateral intercostal thoracotomy was performed in 82% of cases requiring thoracic access, with intercostal muscle myectomy needed in some cases to improve exposure 3
• For complete cardiac exposure, rib resection (typically the fifth rib) provides adequate access through the thoracic sling, with surgical duration under 45 minutes 4

Recovery Support Systems

Anderson Sling Application

• The Anderson Sling suspension system can be used to recover high-risk horses from general anesthesia by supporting them in a standing position within a padded recovery stall 5
• This system had a 97% success rate (31 of 32 recovery events) with no complications associated with the sling or recovery protocol 5
• The sling should be considered for horses at increased risk for injury during recovery from anesthesia, particularly those with compromised thoracic sling function from trauma or surgery 5

Prognosis and Outcomes

• The prognosis for horses with penetrating thoracic wounds affecting the thoracic sling region is favorable (73% discharge rate) when extrathoracic injury is absent 2
• Horses requiring euthanasia had severe trauma to structures outside the thoracic cavity rather than thoracic sling injuries themselves 2
• Following standing lateral thoracotomy through the thoracic sling, 88% of horses survived to discharge and 46% returned to their previous level of athletic activity 3

Common Pitfalls

• Failing to monitor horses with axillary wounds closely for respiratory distress can result in missed pneumothorax or hemothorax development 2
• Inadequate evaluation of the full extent of penetrating wounds may miss concurrent abdominal injuries that determine prognosis 2
• Underestimating the structural importance of the thoracic sling for weight-bearing and locomotion can lead to premature return to work following injury 3