The nature of the trauma can direct diagnostic and therapeutic efforts. Blunt trauma is commonly associated with thoracic and abdominal bleeding, organ rupture, fractures, and neurologic injuries. Penetrating trauma is typically localized to the path of the penetrating object, which is rarely a straight line. Falling from a height causes long bone and facial bone fractures as well as thoracic injuries. A dog bitten by another larger dog can have deep penetrating bite wounds as well as spinal injuries and tracheal rupture from the shearing forces sustained during thrashing motions. Resuscitation of the airway, breathing, and circulation; control of hemorrhage; and pain relief are followed by a careful evaluation of the nervous system, chest, abdomen, integument, and musculoskeletal system.
The traumatized animal should be approached as if multiple injuries are present. The neck and spine should be immobilized until a thorough examination for spinal fractures or luxations is made. Thoracic auscultation for cardiac arrhythmias and the presence and quality of lung sounds should be done to identify chest injuries. The abdomen should be palpated for pain, fluid, or hernias. Extremity fractures should be supported by bandages or splinted to prevent further injury if there is significant swelling or displacement of bone. Because many problems are not apparent for 12–24 hr after trauma occurs, careful monitoring allows early detection of potentially life-threatening complications.
Initial diagnostic work should include the minimum database before fluids are administered. Point-of-care tests should minimally include a PCV, total solids, BUN test strip, and blood glucose. An extended initial database includes arterial or venous blood gases, electrolyte panel, blood lactate, and prothrombin time/partial thromboplastin time. This baseline information is used to create the initial treatment plan and to provide the baseline for subsequent monitoring. Survey lateral radiographs of the chest and abdomen at presentation can demonstrate the initial changes resulting from thoracic and abdominal trauma.
Pulmonary contusions, pneumothorax, cardiac arrhythmias, pleural hemorrhage, pericardial hemorrhage, rib fractures, flail chest, and diaphragmatic hernia are but a few of the potentially life-threatening complications that must be considered in thoracic trauma. Oxygen supplementation and analgesics allow careful physical examination. An ECG, thoracic radiographs, blood gas analysis, and diagnostic or therapeutic centesis aid in determining the extent and severity of the problems.
Severe pulmonary contusions cause hypoxemia, labored breathing in a pattern consistent with parenchymal disease, and crackles and rales on pulmonary auscultation. If the animal does not improve with supplemental oxygen, rapid sedation, intubation, and positive-pressure ventilation with 100% oxygen are indicated. The airway should be suctioned to evacuate blood and debris that is obstructing the flow of air.
Labored breathing with dyssynchronous movement of the chest and abdomen (short, choppy breathing) is consistent with pleural air or fluid, and warrants immediate thoracocentesis. Thoracocentesis should be performed before taking radiographs in animals with respiratory distress. When a negative pressure cannot be achieved, repeated thoracocentesis or continuous drainage of the pleural space by chest tube is required. Large quantities of whole blood removed on thoracocentesis or ongoing leakage of air after 72 hr of pleural drainage are indications for surgical exploration of the chest.
The thoracic focused assessment with sonography technique (TFAST) can be helpful in diagnosing pneumothorax, hemothorax, or thoracic wall trauma, and provides an alternative to radiographs when performed by someone skilled and familiar with sonographic changes associated with these injuries. The chest cavity should be palpated for rib fractures with displaced bone, flail segments, avulsion of ribs, torn intercostal muscles, and herniations. When flail segments impair ventilation, the segment is stabilized by securing it to an external frame of metal rods or splint and cast material formed to the shape of the chest. Penetrating bite wounds over the chest should be explored under anesthesia for debridement and drain placement; if the wound is penetrating, the thorax may be surgically entered to inspect damage to underlying tissue, repair or debride that tissue as necessary, and lavage the thoracic cavity to decrease contamination.
The heart should be ausculted, and an ECG evaluated for arrhythmias. The most common arrhythmias seen with thoracic trauma are sinus tachycardia, ventricular premature contractions, and ventricular tachycardia. Treatment with lidocaine is warranted if the arrhythmias impair perfusion, if the rate is rapid and sustained (>180 bpm in dogs), if ventricular premature contractions are multiform, or if there are prefibrillatory rhythms (R on T phenomenon, torsades de pointes, ventricular flutter).
The extent and severity of abdominal injuries are not initially obvious unless there is visceral herniation outside the body cavity. The abdominal surface should be examined closely for evidence of bruising, abrasions, lacerations, protrusions, localized swelling, herniations, distention, and pain. Animals with evidence of abdominal pain and in shock are considered to have intra-abdominal hemorrhage until proved otherwise. Rupture or laceration of the spleen or liver are the most common sources of intra-abdominal hemorrhage. However, all abdominal organs are susceptible to the shearing forces from blunt trauma. Other common sources of abdominal bleeding include an avulsed mesenteric vessel or damaged muscle or avulsion of the kidneys in the retroperitoneal space.
Approximately 40 mL/kg or half of the circulating blood volume is necessary before free blood in the abdominal cavity will be evident by palpation or visual inspection. Abdominal distention from hemorrhage may become apparent if aggressive fluid resuscitation increases blood pressure and disrupts one or more blood clots that provided hemostasis. Small volume fluid resuscitation to achieve a low normal blood pressure endpoint (90 mm Hg systolic) is indicated to avoid sudden increases in arterial or venous pressures. When ongoing abdominal hemorrhage is confirmed, hind limb and abdominal binding (see Evaluation and Initial Treatment of the Emergency Patient: Hind Limb and Abdominal Binding) is indicated early to reduce the amount of hemorrhage until hemostasis is accomplished.
After injury of any abdominal organ, clinical signs of organ dysfunction or hollow viscus rupture typically develop over a period of hours. Acute abdominal pain is a key physical finding. Survey abdominal radiographs can demonstrate organ displacement, distention, rotation, or free abdominal gas or fluid. Fluid can be recovered by 4-quadrant abdominocentesis. Using the focused assessment with sonography technique (FAST, see Evaluation and Initial Treatment of the Emergency Patient: Hemostasis), even small amounts of free fluid in the abdomen can be identified and aspirated using ultrasound guidance.
When free fluid is not readily identified, a diagnostic peritoneal lavage can be done. A fenestrated catheter is placed into the peritoneal space, and warm isotonic saline (20 mL/kg) infused into the abdomen. The fluid is allowed to dwell for several minutes and distribute throughout the abdomen; it is then drained and evaluated.
Clear fluid indicates that the possibility of significant abdominal hemorrhage is minimal. Fluid with a 1% PCV indicates mild abdominal hemorrhage, while fluid with a PCV >5% indicates significant abdominal hemorrhage that warrants careful monitoring.
Fluid obtained from the abdomen should be examined cytologically for evidence of WBC, plant or meat fibers, free bacteria, or bacteria within WBC. Biochemical evaluation for creatinine and potassium, bilirubin, amylase, and phosphorus help identify urinary system rupture, gallbladder rupture, pancreatic injury, or ischemic bowel, respectively. Abdominal fluid glucose that is 20 mg/dL or more below peripheral blood glucose is characteristic of a septic peritonitis and warrants exploratory surgery. The abdominocentesis, peritoneal lavage, or FAST ultrasound scan can be repeated in several hours if fluid from the first assessment did not indicate a significant problem but the clinical signs continue or progress. Retroperitoneal hemorrhage, fascial hemorrhage, or hemorrhage into the GI system can be difficult to identify.
Criteria for emergency exploratory laparotomy include ongoing hemorrhage; inability to stabilize shock; organ rotation, entrapment, or ischemia; diaphragmatic hernia; and evidence of organ rupture or peritonitis. Surgery to repair a diaphragmatic hernia should not be delayed, particularly with gastric displacement into the thoracic cavity, respiratory compromise, or ongoing hemorrhage.
Retroperitoneal, severe fascial compartment hemorrhage (associated with pelvic fractures), or hemorrhage into a hollow viscus is suspected in acutely traumatized animals that still have signs of a declining PCV, nonresponsive hemorrhagic shock, and no significant findings on abdominocentesis, peritoneal lavage, or FAST scan. Radiographs typically show expansion and loss of detail in the retroperitoneal space. An IV pyelogram should be done to help delineate disruption in the renal vascular supply or in the retroperitoneal portion of the ureter before proceeding with exploratory surgery in this situation.
Last full review/revision March 2012 by Rebecca Kirby, DVM, DACVIM, DACVECC; Andrew Linklater, DVM, DACVECC