There is limited data on TBI in animals. Anticipate TBI in MWDs after trauma in 25-40% of cases.2-6 TBI carries an extremely high mortality; assume a prehospital mortality of >40% in severe TBI cases. Management of MWDs is largely based on recommendations for treating people. Care by HCPs should be directed at efforts to mitigate secondary injury from hypotension, hyperthermia, hyper- and hypoglycemia, hypoxia, hyper-and hypocapnia, acid-base imbalances, electrolyte imbalances, SIRS, MODS, and ARDS. Thus, HCP care should be directed at maintenance of blood pressure, normoxemia, normal ventilation, and normal body temperature.

 

Clinical Signs Suggesting TBI

Brain injury should be suspected in any trauma patient with altered mentation (coma, stupor, depression, lethargy, inappropriate behavior or responses) or with physical evidence of head trauma (e.g., lacerations, abrasions, bruising, swelling, pain, bleeding from the nose or ears).

  • Pay special attention to the patient‘s level of consciousness (LOC), overall pain response, pupillary light responses, cardiac and respiratory changes, motor activity and reflexes, and body temperature.
  • The external ear canals and nasal openings should be examined for evidence of blood or CSF.
  • The presence of lateralizing neurologic signs in a patient with brain injury suggests underlying intracranial hemorrhage; whereas patients with diffuse CNS deficits more probably have significant intracranial edema as a cause or contributor to their neurologic dysfunction.2-5 These findings will affect treatment options.
  • MWD posture on presentation may allow injury localization and estimation of prognosis. While these classic postures are not always noted, their presence can be used by first responders to identify severe TBI with poor-to-grave prognoses.
  • Patients with injury to the T2-L2 thoracic spine often display the Schiff-Sherrington syndrome (Figure 47, inset A), typically with normal mentation, forelimbs in extensor rigidity, and hind limbs that are flaccid. The prognosis for these patients is usually grave due to severe spinal cord trauma.
  • Patients with decerebellate rigidity (Figure 47, inset B) typically are obtunded or depressed, have opisthotonus, have fore limbs in extensor rigidity, and hind limbs in active flexion. These patients have a guarded prognosis due to severe injury to the cerebellum.
  • Patients with decerebrate rigidity (Figure 47, inset C) typically are obtunded, have opisthotonus, and the fore limbs and hind limbs are in extensor rigidity. The prognosis for these patients is grave due to severe injury to the cerebrum.

 

Figure 47.  Characteristic Neurologic Postures on Presentation

Figure 47.  Characteristic Neurologic Postures on Presentation

Assessing Severity of TBI in MWDs

A modified veterinary Glasgow Coma Scale (GSC) (Table 22) is validated for use in dogs.7 Data is limited, however, correlating long-term outcome (i.e. prognostication) with initial or serial assessment of GCS in dogs.

  • As with people, the lower the total GCS, the worse the TBI and the lower the expected survival with neurological function intact.
  • Limited use in veterinary trauma patients has allowed development of suggested prognoses based on the MVGCS (See Table 23). HCPs should use this guidance when assessing severity of TBI and resource allocation.

 

Table 22.  Modified Veterinary Glasgow Coma Scale

Table 22.  Modified Veterinary Glasgow Coma Scale

Table 23.  Suggested Prognoses Based on Modified Veterinary Glasgow Coma Scale

Table 23.  Suggested Prognoses Based on Modified Veterinary Glasgow Coma Scale

General Management Considerations for MWDs with TBI

It is critical to ensure adequate resuscitation and management of cardiovascular and respiratory problems, as hypotension, poor tissue perfusion, and hypoxia lead to progressive brain injury due to the adverse effects of secondary neurological injury due to ischemia, cerebral edema, reperfusion injury, and so forth. (See Figure 48.)

  • Follow guidance in this CPG for management of shock, hypotension, hypovolemia, hemorrhage control, and respiratory dysfunction.
  • Be prepared to intubate patients that are not breathing or have depressed ventilation; careful intubation using manual in-line stabilization (MILS) is essential to minimize further injury.
  • Focus care on preventing hypoxemia, maintaining cerebral perfusion pressure and systemic arterial pressure in the normal ranges, and preventing secondary ischemic cerebral injury.
    • Provide 100% oxygen by facemask. Monitor respiratory rate and effort. Be prepared to intubate and provide supplemental oxygen by ET tube. Maintain arterial carbon dioxide content in the normal range using assisted manual ventilation. Avoid hyperventilation!
    • Maintain normotension (MAP 70-80 mmHg or systolic BP >90 mmHg). Start IV crystalloid fluid therapy to correct shock and provide ongoing volume support (See CPG 6, Figure 33). Measure blood pressure if possible; otherwise, guide fluid therapy based on presence or absence of distal pulses. Consider hypertonic saline (4 mL/kg IV over 5 min) or hyperoncotic fluid (HES, 10 mL/kg IV) boluses if hypotension persists despite crystalloid use.
    • Nurse with head elevated 300 with neutral neck position, avoid external jugular vein compression and catheters, avoid procedures that stimulate coughing or sneezing.
    • If evacuation will be prolonged and the patient is recumbent, rotate lateral recumbency and lubricate the eyes with ophthalmic ointment every 4 hours and maintain in a well-padded area.
    • If the MWD is conscious, restrict activity and movement (e.g., portable kennel), which may require sedation and analgesia (See CPG 16).
    • Give mannitol, 1.5 grams/kg, IV, over 30 min for MWDs with a MVGCS score of ≤ 8. Repeat this dose once more 4-6 hours after the first dose. Note that dogs are less likely to suffer subdural or intracranial hemorrhage; thus, mannitol should be used early in any MWD with moderate-to-severe TBI (MVGCS ≤ 8).
    • Do NOT use corticosteroids to treat MWDs with TBI.

 

 Figure 48.  Management Algorithm for TBI for MWDs

 Figure 48.  Management Algorithm for TBI for MWDs