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Basics ⬇

Outline

Basics

Definition!!navigator!!

  • May be penetrating or blunt
  • Penetrating trauma usually results from collision with an object
  • Blunt trauma often occurs in neonatal foals at parturition

Pathophysiology!!navigator!!

Fracture of bones of the thoracic cage, lung injury, air in the pleural space and mediastinum, diaphragmatic injury, and heart or large vessel injury may occur. Concurrent trauma to the abdomen is also possible.

  • Axillary laceration—often the result of a horse running into a fence or barbed wire. Can be accompanied by severe subcutaneous emphysema, pneumomediastinum, PTX
  • Pulmonary contusion—occurs when the chest wall is compressed against the lung parenchyma. May cause hemorrhage into the alveolar spaces and induce respiratory distress, and pneumonia
  • Pulmonary laceration—a traumatic disruption of the lung that causes PTX or HTX. Caused by a sudden compression of the thoracic wall or direct puncture of the lung. Complications such as pulmonary abscess or bronchopleural fistula may arise
  • PTX causes varying degrees of lung collapse and inadequate ventilation
  • Fractured ribs cause pain and may lead to hypoventilation. When combined with pulmonary contusions, can lead to pneumonia
  • Pericardial effusion may result from hemopericardium, septic pericarditis, or hydropericardium, and potentially lead to cardiac tamponade
  • Transdiaphragmatic perforation can cause viscus rupture, septic peritonitis, and herniation of abdominal organs

Systems Affected!!navigator!!

  • Respiratory—PTX, rib fracture, and pulmonary contusions or lacerations
  • Cardiovascular—cardiac tamponade, large vessel, and intercostal artery or pulmonary parenchymal vessel
  • Gastrointestinal—foreign body penetration of the abdominal cavity

Incidence/Prevalence!!navigator!!

  • Penetrating trauma is rare
  • Blunt trauma occurs in 20% of newborn foals (primiparous and dystocia) at birth but clinical signs are rare
  • In foals referred to neonatal intensive care units, fractured ribs were identified in 65%; mortality attributable to rib fractures may be as high as 25%

Signalment!!navigator!!

Neonatal foals are predisposed to rib fracture and costochondral fracture/dislocation.

Signs!!navigator!!

Historical Findings

  • History of penetrating or blunt trauma
  • History of dystocia or birth from a primiparous mare

Physical Examination Findings

  • Palpation of the thoracic cage and axillary area to detect penetrating wound, edema, fractured ribs, subcutaneous emphysema, or thoracic wall instability and asymmetry
  • Cyanotic or pale mucous membranes
  • Absence of lung sounds—suggestive of PTX
  • Reduced lung sounds ventrally—suggestive of HTX

Causes!!navigator!!

  • Collision with an object, particularly fences, is the most common cause of penetrating thoracic wounds
  • Birth trauma most likely results from compression of the thorax during passage through the dam's pelvic canal

Risk Factors!!navigator!!

  • Horses at pasture, horse getting loose
  • Dystocia and foals from primiparous mares

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

As these horses may suffer from polytrauma, an approach consisting of a first look, shock and emergency treatment, recheck, and then diagnosis is suitable.

Differential Diagnosis!!navigator!!

  • Pain can cause rapid shallow breathing
  • Diaphragmatic hernia
  • Pneumonia
  • HTX, pleural septic effusion, or hydrothorax

CBC/Biochemistry/Urinalysis!!navigator!!

Stress leukogram may be observed. Leukocytosis and increased acute-phase proteins are common with secondary bacterial infection; anemia caused by blood loss.

Other Laboratory Tests!!navigator!!

Arterial blood gas analysis.

Imaging!!navigator!!

Thoracic US

  • T-FAST to quickly detect PTX (see chapter Pneumothorax) and accumulation of pericardial or pleural fluid. Otherwise a complete examination of the entire thorax is recommended to detect fractured ribs or diaphragmatic hernia
  • Foreign bodies or lung contusion may also be identified

Thoracic Radiography

PTX, radiopaque foreign objects, effusion, fractured ribs, or diaphragmatic hernia may be seen. However, radiographs are less sensitive than US for the detection of rib fractures.

Other Diagnostic Procedures!!navigator!!

  • Thoracocentesis confirms a diagnosis of tension PTX or HTX (see Treatment)
  • Thoracoscopy to evaluate the pleural space, potential non-radiopaque foreign bodies, and pulmonary pathology
  • Abdominal US and paracentesis when abdominal cavity perforation is suspected

Pathologic Findings!!navigator!!

  • HTX
  • Rib fracture and flail chest
  • Pulmonary contusion or laceration
  • Large vessel injury, hemopericardium, and cardiac laceration
  • Diaphragmatic laceration
  • Intestinal or abdominal organ injury
  • Septic pleuritis or peritonitis
  • Extrathoracic trauma

Treatment ⬆ ⬇

Outline

TREATMENT

Aims!!navigator!!

  • Support and restore respiratory function
  • Treat shock if necessary
  • Close wound whenever possible
  • Administer broad-spectrum antibiotics, anti-inflammatory and analgesic drugs

Appropriate Health Care!!navigator!!

  • Emergency care and continuous monitoring for severe cases
  • Inpatient care until stabilized

Nursing Care!!navigator!!

  • Oxygen by nasal insufflation to hypoxemic patients
  • Control of external hemorrhage and shock treatment with IV fluids (hypertonic/isotonic) during the acute period. Blood or plasma transfusions should be considered in cases of severe blood loss. Contused lungs are extremely sensitive to crystalloid fluid overload
  • Temporarily close penetrating wounds
  • Decision to decompress the pleural cavity (air or blood) should be based on:
    • Exacerbation of clinical signs when the wound is sealed
    • Presence of a tension PTX or an increase in PTX size
    • Presence of a large accumulation of blood in the pleural space
    • Presence of HTX combined with a penetrating thoracic wound
  • The site for air evacuation is the dorsal thoracic cavity just in front of the 12th to 15th ribs. The site for fluid evacuation is the ventral thoracic cavity and is best evaluated by US (usually, the fifth to eighth intercostal spaces). Avoid intercostal vessels along the caudal border of the ribs
  • Perform thoracocentesis using a 14 G over-the-needle catheter, a teat cannula, or a large-gauge needle attached to a 3-way stop cock, extension set, and 60 mL syringe
  • For severe or active PTX or HTX, place a thoracostomy tube in the pleural cavity, and attach to a Heimlich valve, a “home-made tip-truncated unlubricated condom,” or continuous-suction apparatus in cases of rapid reaccumulation. Evacuation pressures ≤20 cmH2O should be used, and the air or fluid should be removed from the thorax slowly
  • Drain pericardial effusions when cardiac tamponade is detected. Ideally, a 14 G over-the-needle catheter is inserted through the pericardium under US guidance. ECG monitoring is recommended
  • Fractured ribs are usually not stabilized, but rough edges may be rongeured and fragments removed in cases of open fracture. Indications for internal fixation are:
    • Displaced fractures of the third to sixth ribs at the costochondral junction on the left side, with lower fragment pressing in towards myocardium
    • Fractures of caudal ribs resulting in laceration of diaphragm or diaphragmatic hernia
    • Foals with existing extensive internal thoracic trauma
    • Presence of flail chest (3 or more consecutive ribs that are each fractured in at least 2 sites, resulting in a free-floating segment of the chest wall and paradoxical associated respiration) with severe respiratory dysfunction

Activity!!navigator!!

  • Box stall rest
  • Confine foals with fractured ribs for a minimum of 2–3 weeks, and, if possible, avoid manipulations

Client Education!!navigator!!

  • Discuss clinical signs of PTX, and advise immediate return with recurrence
  • Inform of potential complications. Reevaluation is recommended if wound drainage occurs

Surgical Considerations!!navigator!!

  • Standing surgery when possible
  • Stabilization of the patient, decompression of the PTX, and positive-pressure ventilation are mandatory for surgery under general anesthesia
  • Suture wounds whenever possible to rapidly achieve an airtight seal. Conservative debridement is advised to permit primary closure. If impossible, apply an occlusive bandage
  • Consider thoracoscopy for severe or recurrent PTX or when a foreign body is suspected
  • Certain types of rib fractures may be successfully reduced and stabilized in foals using reconstruction plates, self-tapping screws, and cerclage wire or nylon strand suture
  • Wound or thoracic exploration is indicated for uncontrolled hemorrhage

Medications ⬆ ⬇

Outline

MEDICATIONS

Drug(s) of Choice!!navigator!!

  • Broad-spectrum antibiotics for patients with penetrating wounds
  • NSAIDs to avoid splinting and hypoventilation because of pain from fractured ribs. If pain is not controlled, long-lasting intercostal blocks (bupivacaine) or opioid analgesics may be indicated

Precautions!!navigator!!

Drugs such as xylazine or opioids may reduce PaO2.

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Patient Monitoring!!navigator!!

  • Respiratory rate and effort, heart rate, auscultation, hematocrit, and total solids during the first 48 h
  • Blood gas analyses for signs of hypoventilation
  • Thoracic US and radiography can be repeated every 24–48 h until the condition is stable

Possible Complications!!navigator!!

  • Recurrence of PTX or HTX
  • Pyothorax
  • Bacterial pneumonia in young foals
  • Septic peritonitis and shock when intestinal viscus penetration has occurred
  • Rib and sternal fistulae
  • Diaphragmatic hernia

Expected Course And Prognosis!!navigator!!

  • Tension PTX and cardiac tamponade are serious life-threatening conditions
  • Cardiac or large vessel laceration carries a poor prognosis
  • Full recovery is expected if the injury is not severe and does not involve the large vessels, heart, or abdominal cavity

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Associated Conditions!!navigator!!

  • Fractured ribs
  • Diaphragmatic hernia
  • Ruptured trachea
  • Thoracic and abdominal organ lacerations
  • Other complications of trauma

Abbreviations!!navigator!!

  • HTX = hemothorax
  • PaO2 = partial pressure of oxygen in arterial blood
  • PTX = pneumothorax
  • T-FAST = thoracic focused assessment with sonography for trauma
  • US = ultrasonography, ultrasound

Suggested Reading ⬆ ⬇

Bellezzo F, Hunt RJ, Provost R, et al. Surgical repair of rib fractures in 14 neonatal foals: case selection, surgical technique and results. Equine Vet J 2004;36(7):557–562.

Jean D, Laverty S, Halley J, et al. Thoracic trauma in newborn foals. Equine Vet J 1999;31(2):149–152.

Jean D, Picandet V, Macieira S, et al. Detection of rib trauma in newborn foals in an equine critical care unit: a comparison of ultrasonography, radiography and physical examination. Equine Vet J 2007;39(2):158–163.

Laverty S, Lavoie JP, Pascoe JR, Ducharme N. Penetrating wounds of the thorax in 15 horses. Equine Vet J 1996;28(3):220–224.

Radcliffe RM. Thoracic injury in horses. In: Orsini JA, Divers TJ, eds. Equine Emergencies: Treatment and Procedures, 4e. St. Louis, MO: Elsevier Saunders, 2014:728–732.

Schambourg MA, Laverty S, Mullim S, et al. Thoracic trauma in foals: post mortem findings. Equine Vet J 2003;35(1):78–81.

Sprayberry KA, Barrett EJ. Thoracic trauma in horses. Vet Clin North Am Equine Pract 2015;31(1):199–219.

Author(s) ⬆

Authors: Florent David and Sheila Laverty

Consulting Editors: Mathilde Leclère and Daniel Jean