Trauma is a common cause of emergency presentations in small animal practice. Due to our patients’ small size the potential for multi-system damage is high and their injuries need to be approached in a systematic manner to ensure that no life-threatening abnormalities are missed. Appropriate management in the first few hours is vital for success. Many patients benefit from a multi-modal approach in the successive days, concentrating on careful nursing, nutrition and pain relief.

Primary Assessment

A major body system assessment approach should be used to rapidly identify the life-threatening problems and initiate life-saving treatment. The major body systems are:

• Cardiovascular
• Respiratory
• Neurological

Cardiovascular

Cardiovascular assessment is aimed at identification of hypoperfusion as a result of hypovolaemia. Significant blood loss can occur into body cavities and fracture sites without visible haemorrhage. This is especially true in cats. The response to hypovolaemia is initially tachycardia, vasoconstriction and increased myocardial contractility as a result of adrenergic stimulation. With continued blood loss, these compensatory measures fail to maintain tissue perfusion and signs of decompensated hypovolaemic shock ensue.

The response of dogs to blood loss is predictable and the degree of hypoperfusion can be estimated from the severity of their clinical signs (see table below). Cats are less predictable and more difficult to assess. Their higher resting heart rate also means there is less room for an increase in heart rate. We are therefore more reliant on palpation of pulse quality for assessment in these patients. Assessment of the severity of hypovolaemia is used to guide fluid therapy.

Respiratory

Respiratory assessment is aimed at identification of dyspnoea and identification of the underlying cause. All patients presenting with dyspnoea should be provided with immediate oxygen therapy in the least stressful manner possible.

Common causes of dyspnoea following trauma include:

• Pneumothorax
• Pulmonary contusions

Less common causes include diaphragmatic hernia and chest wall trauma.

Significant haemothorax is an extremely rare cause of dyspnoea as in these patients the signs of hypovolaemia predominate.

Traumatised animals should therefore be assessed carefully for lung sounds; all areas of the thorax should be carefully auscultated. Some of these patients can be extremely challenging, especially those that have both pneumothorax and pulmonary contusion. Pleural space disease (dull lung sounds) should prompt needle thoracocentesis.

Neurological

In the primary assessment of these patients, neurological assessment is limited to mentation, posture and assessment for limb movement and deep pain. Patients with severe cardiovascular compromise should not be assessed for neurological function until they are more stable.

Mentation: Patients with coma or stupor (response only to pain) are likely to have intracranial injury. Reduced mentation in the absence of cardiovascular abnormalities should prompt evaluation for head injury.

Posture: Decerebrate rigidity (extensor rigidity in all four limbs with associated abnormal mentation, opisthotonus may or may not be present) is associated with caudal midbrain or cerebellum injury. This posture has a grave prognosis for recovery.

Decerebellate rigidity: (extensor rigidity of forelimbs, flexion of hind limbs with opisthotonus and normal mentation) is associated with caudal cerebellar lesions. This carries a better prognosis.

Schiff-Sherrington posture: (Extensor rigidity of forelimbs, flaccid, atonic, areflexic, analgesic pelvic limbs, normal mentation) is associated with an acute, severe, T3–L3 lesion. Prognosis has typically been thought to be poor for full recovery of motor function, however with time some of these positions can recover.

Management of Major Body System Abnormalities

Cardiovascular

Mortality in hypovolaemic shock is related to duration of the ischaemic insult. Early replacement of circulating volume is key to successful patient management.

Stabilisation of the cardiovascular system is aimed at replacement of lost circulating volume with intravenous fluid therapy. First choice is always isotonic crystalloid fluids, e.g., lactated Ringer’s solution.

The volume of fluid given is based upon the severity of hypoperfusion. A proportion of ‘shock dose’ is administered over a short period of time (15–20 minutes) and the patient reassessed. For example, in a patient assessed to have moderate hypovolaemia a volume of 20 ml/kg is administered over 15 minutes and the patient reassessed. The patient’s response to therapy will ultimately determine the approximate volume to be given. Isotonic crystalloids are effective in the majority of cases. If the patient is responding poorly to fluid resuscitation, the use of other fluid types should be considered in conjunction with evaluation for the site of on-going haemorrhage.

There is on-going debate whether to use crystalloids or colloids for resuscitation. The on-going debate is testimony to the fact that there is little difference between the two types of fluids. Colloids in theory are more efficient and have a better persistence than crystalloids.

Respiratory

On arrival at the practice it is likely that the animal will have endured a car journey and therefore be stressed at the unfamiliarity of the situation. The patient should be provided with oxygen supplementation whilst a brief examination of the respiratory tract is carried out to rule out easily treatable conditions. The patient should then be left to relax (as much as is possible).

In severely dyspnoeic animals, actively taking control of the airway (which often only requires very small doses of sedative in severely dyspnoeic animals) is vastly superior to intubating them following a respiratory arrest. The decision, although a big step, may be lifesaving in conditions such as upper respiratory tract obstruction secondary to brachycephalic obstructive airway syndrome, or laryngeal paralysis. It is important to gain a capsule history with particular reference to pre-existing disease, concurrent medication, history of trauma and onset and progression of the condition.

The first part of the evaluation of the respiratory tract should be to watch and listen without a stethoscope. An enormous amount of information can be gleaned from just observation, before even touching the patient. In normal animals, the majority of inspiration is due to diaphragmatic contraction, therefore little chest wall movement is seen. As the diaphragm contracts the abdominal contents are pushed caudally and therefore the abdominal wall moves out. In cats and small dogs where the abdomen moves in with inspiration, is seen in conditions preventing adequate lung inflation with respect to thoracic wall movement and indicates severe respiratory compromise. Conditions causing this include: upper airway tract obstruction, diaphragmatic rupture or paralysis, decreased lung compliance and pleural effusion (particularly in cats).

One should also be aware of the postural manifestations of dyspnoea such as extended neck, abducted elbows, open mouth breathing, an anxious facial expression, increased abdominal movement and paradoxical abdominal movement. Straightening of the neck and open mouth breathing occur in both dogs and cats, however, some other postural manifestations of more severe dyspnoea vary between species. Dogs prefer to stand with abducted elbows, whilst cats tend to sit in sternal recumbency. Constantly changing body position in cats implies a much worse degree of dyspnoea than it does in dogs. Lateral recumbency due to dyspnoea is a serious sign in a dog and it often means impending respiratory arrest in a cat.

The differentiation between inspiratory and expiratory dyspnoea can also aid in the localisation of the disease process. Inspiratory dyspnoea with stridor or stertor is associated with dynamic upper airway obstruction, in cats chronic pleural effusions may be associated with inspiratory dyspnoea without stertor. Expiratory dyspnoea is a feature of feline allergic airway disease. Most other causes of dyspnoea will be associated with mixed respiratory patterns. Short shallow respiration and sometimes panting may be seen in some pneumothoraces.

Pulmonary Auscultation

Auscultation is an art that with practice can be learnt and perfected by all. It requires a methodical approach and a decent stethoscope. All lung fields should be auscultated, this is easily accomplished by dividing the thorax into a nought and crosses board, i.e., 9 smaller areas. If lungs sound dull you should be cross referencing at all stages with respect to what you would expect given the degree of dyspnoea. In normal lungs increased lung noise is expected in the cranioventral lung fields. This is due to increased turbulence in these smaller airways. The lungs should be symmetrical left to right in similar fields.

Abnormal sounds are associated with a number of different disease processes within the airways. Increased respiratory rate and effort should cause increased harshness within the lung fields, so one should cross reference findings with what would be expected given the degree of respiratory embarrassment.

The distribution of the abnormal lung sounds can provide information as to the cause of the disease. Adventitious lung sounds are associated with parenchymal disease. It is somewhat easier to classify abnormal lung sounds as either:

• Harsh—i.e., louder and coarser than normal
• Crackles—either fine or coarse, associated with lower airway or parenchymal disease

A cranioventral distribution or crackles or harshness in dogs is associated with aspiration pneumonia. Cardiogenic oedema may be associated with sounds loudest over the heart base. Neurogenic oedema is seen most commonly in puppies after cervical trauma or upper respiratory tract obstruction. This usually results in a caudodorsal distribution of crackles.

Pleural space disease is associated with the absence of lung sounds. The pattern of dullness provides information as to the possible cause:

• Dorsal dullness—associated with accumulation of air, pneumothorax
• Ventral dullness—fluid or soft tissue
• Gut sounds may be heard with diaphragmatic hernias.

Animals that have been hit by cars and have pneumothoraces and pulmonary contusions may complicate auscultation. The contusions cause harshness, whereas the pneumothorax dampens sounds down, resulting in overall normal sounding lung sounds.

All dyspnoeic (and hypoperfused) patients will benefit from oxygen therapy. This should be provided in a stress-free environment. Initially this is most likely to be via an anaesthetic circuit and these are often better tolerated than masks. If on-going oxygen therapy is required the use of an oxygen tent should be considered. Patients that are severely dyspnoeic should have a brief targeted examination to identify for the presence of pleural space disease. If this is not present no further stress should occur to the patient and they should be allowed to recover for a period of time in an oxygen enriched environment. Certainly, in trauma patients radiographs should not be made without careful consideration of risks/benefits. It is unlikely to change your immediate treatment plan.

If the cause of dyspnoea is thought to be pneumothorax this should be addressed as soon as possible with needle thoracocentesis. Thoracic drain placement is rarely required and anaesthesia for placement may be associated with significant morbidity. Repeat needle thoracocentesis can be performed as required as this is a low morbidity and well tolerated procedure in both dogs and cats. Should regular decompression be required placement of a chest drain using a modified Seldinger technique is recommended. The Seldinger technique involves placement of a needle into a cavity (vessel or pleural space) through which a wire is placed. A catheter can then be railroaded into the space over the wire. These kits are commercially available through Direct Medical Supplies and produced by Mila. They are reasonably priced and extremely useful. Traumatic pneumothorax is rarely a surgical condition and the vast majority will respond to conservative management. Some may require 7–14 days to resolve fully, some patience is required!

There is no specific therapy for management of pulmonary contusions. Antibiotics are not indicated as infection is a rare complication. No therapy has been shown to speed recovery. If a patient is severely dyspnoeic as a result of pulmonary contusions any fluid therapy can result in worsening of their signs. Careful risk benefit analysis should be performed prior to administering large volumes at rapid rates. On no account should fluid therapy be withheld in patients suffering severe hypoperfusion. In these situations, patients should be monitored carefully. Some may require artificial ventilation if there is deterioration of their respiration although the prognosis for patients requiring ventilation for pulmonary contusions is extremely poor.

Diaphragmatic rupture is relatively infrequent compared to other causes of dyspnoea. There is less mortality if surgery is performed later rather than as an emergency as this allows stabilisation of other abnormalities. Indications for emergency surgery include displacement of the stomach into the thorax, intestinal volvulus or suspicion of intestinal rupture. Physical examination findings are often seen with diaphragmatic rupture include: dull lung sounds, gut sounds in the thorax, an “empty” abdomen on palpation and paradoxical abdominal movement with respiration. Suspicion of these should prompt thoracic radiographs at some point during diagnostic evaluation, although these can wait in the majority of patients.

Other injuries that may be seen rarely, although they seem to particularly affect cats, include subcutaneous emphysema and pneumomediastinum, occasionally in conjunction with a small pneumothorax. The pathogenesis of this often remains unknown although a small lung laceration or tracheal injury is often suggested. Many of these cats again will respond to conservative management.

Rib fractures are common, but rarely significant. In some patients with no other identified causes of dyspnoea these can contribute to inspiratory dyspnoea related to pain. Local anaesthesia can be used to provide analgesia at the fracture site.

Neurological

Neurological assessment should only really be interpreted in patients that are cardiovascularly stable. Some patients also respond poorly to pain testing in the first few hours after trauma. Any abnormalities found on initial examination should be corroborated later.

Patients with suspected brain injury have inappropriate levels of mentation and often have concurrent head injury. The presence of head injuries does imply there is brain injury.

Where brain injury is suspected, cranial nerve testing should be carried out to evaluate for increased intracranial pressure. Herniation or imminent herniation is associated with deterioration in CNIII function. This is usually seen as unilateral changes in pupillary size. Unresponsive pupils that are mid-size occur with brainstem signs that progress into the medulla and are usually a grave sign. There may also be associated Cushing’s response. This response occurs secondary to increased intracranial pressure (ICP) and results in systemic hypertension and associated secondary bradycardia. The systemic hypertension is an effort to maintain cerebral perfusion pressure (CPP=MAP-ICP).

The primary aim in patients with brain injury is to restore and maintain tissue perfusion and oxygen therapy. Oxygen should be administered and efforts to restore circulating volume initiated.

There is some data to suggest that hypertonic saline (2–4 ml/kg) causes smaller increases in ICP than other fluids and may therefore be the most appropriate first choice. Steroids are not indicated and are associated with significant haemorrhagic gastrointestinal side effects if given at appropriate doses. Mannitol may be considered in patients that are cardiovascularly stable (0.25–1 g/kg over 20 minutes) where there is evidence of increased intracranial pressure, but should not be used when there is concurrent hypovolaemia or pulmonary contusions.

Patients that are deteriorating despite appropriate medical therapy should prompt consideration of surgical intervention. This is a specialist procedure and referral should be sought sooner rather than later.