Spine: fracture / luxation

• Cause: trauma such as a fall or a road traffic accident (RTA).
• Signs: neurological, orthopedic, other serious injuries likely.
• Diagnosis: neurological examination, survey radiographs of spine, CT and MRI of spine.
• Treatment: cage rest, methylprednisolone, external support or surgical stabilization and/or decompression.
• Prognosis: poor if deep pain sensation (nociception) absent.

• Spinal hyperesthesia.
• Suspected traumatic incident.
• Signs of cord damage: upper motor neuron (UMN), or lower motor neuron (LMN), signs. May or may not be able to walk.
• Neurological deficits: from pain to complete paralysis with loss of deep pain sensation (nociception).

• Delayed onset of signs, eg a day or so after trauma.
• Cervical vertebral subluxation, eg small dogs shaken by the neck by a larger dog or head on injury.

• Always acute situation.

• Young animals with no 'road sense'.

• General anesthesiaorsedationmay reduce spinal cord perfusion pressure and exacerbate secondary injury to the spinal cord.
• Investigation of any major trauma case must include examination of cardiovascular and respiratory function.
• Pneumothorax Pneumothorax , pulmonary contusion, traumatic myocarditis, hemoperitoneum, rupture of diaphragm Diaphragm: traumatic hernia , or bladder Bladder: trauma rupture , must be considered.
  Sedation or anesthesia will often influence the results of neurological examination and result in loss of paraspinal muscle tone → unstable vertebral segments may be more likely to subluxate

• Vehicular collision.
• Fall from a considerable height.
• Gunshot injury.
• Dog running into obstacle at high speed.
• Falling object.

Specific

• Fracture or dislocation/luxation.

• Because the spinal cord is encircled by a rigid, inelastic bony encasement (vertebrae), and because of the relatively soft texture of spinal parenchyma, any change in canal diameter results in spinal cord injury.
• Mechanical injury to nervous tissue (especially axons), results in physiologic or morphologic disruption of nervous impulses.
• Contusive injury to the spinal cord causes primary mechanical injury to the parenchyma and vasculature, and secondary damage that is responsible for an expanding zone of necrosis.
• The majority of the secondary damage occurs in the 24-48 hour period after the initial injury, but ongoing apoptotic cell death can be detected months and even years later.
• Numerous pathophysiological consequences may evolve including ischemia, hemorrhage, alterations in spinal cord blood flow and edema.
• These secondary events lead to a self-perpetuating process of damage to the spinal cord that often is equally, if not more, detrimental to the spinal cord than the initial mechanical injury (second injury phenomenon).
• Putative mediators of this self-perpetuating process include excitatory neurotransmitters, endorphins, catecholamines and free radicals released after the intitial insult.
• The different injuries resulting from trauma include vertebral fractures, subluxations and luxations, flexion/extension injuries and traumatic disk herniations.
• Several different types of vertebral fracture and luxation can occur dependent on the combination of loading forces applied and the location along the spine.
• Forces can be divided into axial loading, flexion and extension, and rotational with each producing a different type of vertebral column injury.
• Flexion injuries→ damage to the ventral compartment.
• Extension injuries→ damage to the dorsal compartment.
• Fracture is more common at the junctions of rigid and more mobile parts of the spine, eg thoracolumbar and lumbosacral junctions.
• Ongoing instability can result in repeated contusive injuries, additional laceration of the cord and increasing severity of compression.

• This results from a lesion between T2 to L3 spinal segments that interrupts the ascending inhibitory impulses from the Border cells in the lumbar spinal cord grey matter.
• These cells are present in the dorsolateral part of the ventral grey matter from L1 to L7 with a maximal population from L2 to L4.
• Axons from these cells cross to ascend in the contralateral fasciculus proprius of the lateral funiculus to terminate in the cervical intumescence.
• This loss of ascending inhibition to the thoracic limbs results in extensor rigidity of the thoracic limbs.
• The thoracic limbs, however, are otherwise neurologically normal in terms of gait and postural reactions.
• While Schiff-Sherrington posture is usually seen with acute and severe spinal cord injuries, this posture alone does not indicate that the spinal lesion is irreversible.

• Acute onset, neurological deterioration in first few hours/days after trauma.

• Pain in spinal column/spinal hyperesthesia.
• Neurological deficits.

• As spinal injury frequently occurs in association with multiple organ trauma, it is imperative to determine the presence of other life-threatening injuries:
  • Respiratory and heart rate.
  • Heart rhythm.
  • Degree of peripheral perfusion (capillary refill times, coolness of limbs).
  • Ability to voluntarily move.
  • Level of consciousness.
• The degree of general health may influence subsequent neurological evaluations.
• If, for example, the animal is poorly responsive because of poor perfusion to the brain, latter, accurate assessments for deep pain recognition will be difficult.
• If the animal is mentally alert but unable to move, immediate concerns should be directed toward the neurologic and musculoskeletal systems:
  • Initial observations of posture can be helpful in determining if a neurologic abnormality exists.
  • Schiff-Sherrington posture is characterized by thoracic limb extension and paraplegia with normal to sometimes decreased tone and reflexes in the pelvic limb.

• It is not uncommon that the owners will have witnessed the animal being traumatized and may contact the veterinary surgeon for advice prior to transporting the animal to the hospital.
  Owners should be advised to be cautious when dealing with traumatized animals as they can have severe pain and may become uncharacteristically aggressive.
  Placing the animal on a rigid, movable surface such as a board is ideal. If a rigid surface is not available, placing the animal in a blanket or other sling-like apparatus can be used for movement. Multiple persons to help with moving the animal may decrease the chance of additional injury to the animal during transport.
• Significant history includes:
  • Whether or not the owner witnessed the traumatic event and the relevant circumstances.
  • How long ago the accident occurred.
  • What movement the animal was capable of immediately after the trauma.
  • Was the dog able to walk at some point?
  • Has it been able to urinate on its own?
  • Was the animal normal before the trauma?

• Gunshot injuries to spinal column.

• Pain in affected area of spinal column.
• Misalignment of spine.
• Other evidence of trauma.

• Any degree of neurological impairment up to complete paralysis with no deep pain sensation.
• When nervous system injury is suspected, a complete neurologic assessment is mandatory Neurological examination.
• This examination should allow one to determine lesion(s), location and severity of nervous tissue damage.
• Clinical deterioration during examination is possible due to vertebral instability.
• Such a deterioration can be catastrophic, particularly in patients that have suffered an atlantoaxial injury.
• The examination and diagnostic sequence needs to be modified to accommodate for a possible unstable vertebral segment and the immobilization method used.
• It is not unusual for there to be more than one site of injury and so neurological signs can be multifocal and periphery nerve injury such as brachial plexus avulsion Brachial plexus: avulsion can complicate the clinical assessment.
• Observation of any voluntary movement is noted.
• It is important however, to differentiate voluntary from reflex movements.
• Reflex movements often occur when the animal is touched or physically stimulated, whereas voluntary movements are made without external stimulation.
• Talking to the animal or calling its name may result in attempts by the animal to move the limbs or wag the tail.
• Until definitely proven, voluntary movement should be assumed to be absent.
• In cases of suspected sacrocaudal fracture or luxation, nociception in the tail base and perineal region should be assessed.

• Clinically normal despite significant spinal damage. Later neurological signs/deterioration.

• As some fractures and subluxations can be subtle, good quality, well-positioned spinal radiographs are usually most helpful. This may be accomplished with the animal awake and immobilized Radiography: spine.
  Poor radiographic technique resulting in rotation of the spine (especially in the cervical area), can make assessment for unstable and malaligned vertebral segments difficult.
• Intuitively, survey radiographs provide a static record of the location of the vertebrae at the time of study. However, do not allow for assessment of how extensive the displacement of the vertebrae was at the time of injury and prior to radiology.
• In many instances, the neurological assessment of the severity of spinal injury is most important in establishing the prognosis, regardless of the radiographical features.
• As a result of the strong paraspinal musculature, vertebrae can be significantly displaced acutely at the time of injury, but then subsequently be pulled back into a more normal position. Clinical signs in these animals appear worse than the radiographs would suggest.
• Disturbances in the adjacent soft tissue, such as paraspinal muscle disruption or hematoma may also be an additional radiographic clue to the site of injury.
• Serial radiographs may indicate instability. However, the degree of instability is often difficult to predict. A scheme has been devised in humans for predicting spinal instability based upon the degree of vertebral damage and modified for use in animals. The vertebrae are divided into 3 compartments:
  • The ventral (anterior) compartment - composed of 3/4 of the verebral body and disk, and the ventral longitudinal ligament.
  • The middle compartment - includes the dorsal 1/4 of the verebral body, the disk and dorsal longitudinal ligament.
  • The dorsal compartment - includes the articular facets and joint capsules, the ligamentum flavum and the dorsal vertebral arch and pedicle, and the dorsal spinous processes and interspinous ligaments.
• Damage of two or more components would indicate the need for surgical stabilization.
• It is also important to remember that disruption of the soft tissues of the intervertebral disk, dorsal and ventral longitudinal ligaments, and synovium of the articular facets disrupts all the compartments and causes instability.

Other imaging

• Myelography Radiography: myelography or other advanced imaging such asComputed Tomography (CT) Computed tomography , orMagnetic Resonance Imaging (MRI) Magnetic resonance imaging: spine is needed to establish spinal compression and to ensure that no additional lesions (not seen on survey radiography), are present.
• Because patients with spinal fractures and luxations frequently have vertebral instability, the potential for causing additional injury during positioning to obtain orthogonal views in myelography is of real concern.
• CT is very helpful in determining abnormalities of bone that may not be apparent with survey radiography.
• Three dimensional reconstruction from CT images may provide additional anatomical information regarding bone contour.
• MR imaging has the distinct advantage of showing information regarding intramedullary spinal disease or soft tissue compression of the spinal cord caused by hematoma or ruptured intervertebral disk.
• Bone detail is not as apparent on MRI as with CT.

• Intervertebral disc disease Intervertebral disk: type 1 herniation.
• Discospondylitis Diskospondylitis.
• Neoplasia Spine: neoplasia.
• Fibrocartilagenous emboli (FCE) Fibrocartilaginous embolism.
• Myelitis.
• Pathological fracture associated with neoplasia, infection or metabolic disease.

• Pelvic fractures.

• Acute bilateral cruciate disease Stifle: cranial cruciate ligament disease.

• As with any trauma patient, the first step is to check airway patency, breathing and circulation Trauma: overview. Hypotension and hypoxemia will worsen outcome of spinal cord injury and should be corrected if present.
• If the animal is calm and quiet, it should be further examined in the position it was admitted. Usually this will be a lateral or sternal recumbent position.
• If the animal is struggling to move it should be immediately restrained. This can be accomplished by firmly taping the animal to a rigid back-board or similar structure.
• If a thoracolumbar vertebral trauma is suspected, the animal can be secured with white tape placed over the scapular and femoral trochanter regions.
• If a cervical injury is suspected, the head should be additionally secured.
• 
  Any rigid surface that is movable can be used to support the spine during manipulations and movement. A board 8-10 inch in width, 4-5 feet in length and 3/4-1 inch in thickness works well. Handles can be attached to make it easier to move the board from flat surfaces such as floors. It is also helpful to record the weight of the board directly to enable an accurate body weight to be recorded on the animal even after it has been immobilized
• Cranial nerves, spinal reflexes (assessed in the dorsal limbs), spinal palpation for hyperaesthesia, cutaneous trunci assessment and assessment for deep pain can be performed with an animal in a lateral recumbent position.
• For evaluation of the opposite (down) side, a second back-board is used to 'sandwich' the animal, fascilitating the' flipping' of the animal. Place the second back-board on the upside of the animal. Firmly hold together, trapping the animal between them. If necessary secure the boards together with tape. Flip the animal/board configuration over so that the board previously on the upside of the animal is now down. The animal can be secured to this bottom board as previously described using a single board.

• Corticosteroids may be indicated for shock, but their use to treat spinal cord injury is contentious.
• Methylprednisolone sodium succinate Methylprednisolone (MPSS) has been advocated as a free radical scavenger.
• There is currently no clear evidence that MPSS will improve outcome of spinal cord injury in dogs.
• Methylprednisolone sodium succinate can be given as an initial bolus (time 0) at a dose of 30 mg/kg IV, with additional doses of 15 mg/kg IV given at 2 and 6 hours after the intial dose.
  If the methylprednisolone sodium succinate is given too rapidly in an awake animal, vomiting often occurs. In an animal under general anesthesia, hypotension is often noted. It is therefore, advisable to administer the drug slowly over approximately 5-10 mins

Polyethylene glycol (PEG)

• Polyethylene glycol (PEG) has also been advocated as a therapy of acute spinal cord injury.
• A study in dogs with disk herniations showed it is a safe drug, and may improve outcome, but the outcome of dogs reported in this study was similar to other published case series in which PEG was not administered.
• The recommended dose is 2 ml/kg of PEG (3500 Dalton, 30% w/w in saline) given intravenously over 15 min and then repeated 4 hours later.
• PEG is not commercially available in a medical grade at this time.

Analgesia

• Opiate analgesics are commonly used to alleviate pain.

• Treatments can be separated into surgical and non-surgical categories - in many instances they are combined.
• If instability is noted, spinal stabilisation is indicated. External fixation using splints and bandages may be helpful if applied correctly. Internal fixation and stabilization is often necessary.
• If a fracture or luxation exists, internal surgical fixation may be needed.
• If an intramedullary contusion is present, surgical treatment is rarely indicated, as decompression is of questionable value in this instance.

Non-surgical treatments

Confinement

• Regardless of additional therapies administered, confinement is initially mandatory treatment for any unstable vertebral problem.
• Cage confinement may be necessary for 4-6 weeks in animals with non-surgically managed spinal injury.

External support

• External support bandages or casts Fracture: external fixation have been used if concurrent spinal instability is present.
• The goals of external support should be immobilization of the vertebral segments above and below the damaged area.
• Splints do not protect from compressive loading of the spine, and offer poor protection against rotatory forces.
• After the damaged area has been identified:
  • Place a soft wrap over the body above and below the injured segment.
  • Apply cast padding, covered by cling gauze and bandage.
  • Apply plaster or fiberglass casting material moulded to the shape of the spine as a rigid external support.
  • The authors have had good success using aluminium rods bent in a rectangle shape and contoured to the curvature of the spine. The ends of the rectangular configuration can be bent outward and used as handles which aids manipulation, physical therapy and walking. Additional handles can be fashioned with the bandage to serve the same purpose.
  • Secure the casting material or aluminium rods to the soft wrap using bandage material. White porous tape works well for this purpose.
• Pressure points, particularly between throacic and pelvic limbs, should be checked and padded carefully.
• The thocacic and pelvic limbs need to be included in the splint to immobilize the thoracolumbar junction, and the head and thoracic limbs must be included to immobilize the cranial cervical spine.
• With lower lumbar and lumbosacral fractures, especially in male dogs, the penis or vulva must not be incorporated into the bandage. This may prevent securing the bandage effectively. To prevent urination onto the bandage in males, a plastic shield cut from a used intravenous fluid bag or waterproof pads can be secured to the bandage ventrally. If more protection from moisture damage to the entire bandage is needed, a polythene bag or suitable barrier can be placed over the bandage with the ends tucked into the ends of the bandage.
  The layers of bandage and covering material may result in an increase in the animal's body temperature, especially if the ambient environment is warm - monitor animal's body temperature regularly after placing a bandage to prevent overheating

Surgical treatments

• Indications for surgical treatments of spinal trauma are numerous and often inconsistent among clinicians.
• Some authors suggest that similar results are obtained with both surgical and non-surgical treatments for spinal fracture, irrespective of severity of clinical signs.
• Damage of two or more components using the prediction scheme as outlined previously would indicate the need for surgical stabilization.
• A variety of techniques are available

Internal fixation

• Surgical stabilization is the most effective method of stabilizing an unstable spine, but is associated with significant surgical risks.
• Internal fixation Fracture: internal fixation using a combination of bone screws, Kirschner wires, Steinmann pins, and poymethylmethacrylate (PMMA), cement is most often chosen for stabilization:
  • Screws and pins are used to anchor the PMMA to the bone.
  • Knowledge of normal vertebral and spinal anatomy is important so as to recognize when normal alignment is achieved.
  • Alignment should be performed cautiously and slowly, providing time for overcoming muscle contracture.
  • Lamina spreaders are useful to distract collapsed vertebral segments.
  • Once reasonable alignment is achieved, and if at least one pair of articular facets remain intact, a small K-wire can be driven across the facets to maintain alignment during subsequent screw placement.
  • Place screw either side of the fracture site in the vertebral bodies or articular facets (if facets are large enough).
  • Incorporate these screws with PMMA either in a 'doughnut-shaped' or bilateral 'cigar-shaped' configuration.

Decompression

• Decompression is indicated if myelography indicates spinal cord compression due to intervertebral disk rupture or hematoma.
  Often with fractures and luxations, spinal compression is the result of bony instability and realignment of the spine is all that is needed
• Additional bone removal from the damaged area during laminectomy may increase the amount of instability and make internal fixation more difficult.
  A hemilaminectomy is preferable if decompression is needed as this results in the least amount of instability of all decompressive procedures.
  Myelomalacia can be accurately assessed only after durotomy

• Any deterioration in neurologic status should be investigated using spinal radiography, and potentially advanced imaging if deterioration continues.
• If animals are recumbent for a time, special attention to prevent recumbency complications is necessary:
  • The recumbent animal should be turned at least every 1-4 hours to prevent decubital ulcers from developing on bony protuberances such as hips or shoulders.
  • Extra padding under the dog with foam rubber or thick fleece material is necessary.
  • Small soft-sided waterbeds are helpful in preventing bed sores.
  • Frequent turning is also important in preventing atelectasis which may lead to pneumonia.
  • Ideally, the animal should be kept in a sternal or sternal oblique position to allow for chest expansion.
• The recumbent animal is often unable to move itself from an area it has soiled:
  • Absorbent, waterproof pads can be useful in soaking up urine and preventing the saturation of bedding material with urine or faeces.
  • Frequent bathing may be necessary to prevent urine scald. This may be accomplished during hydrotherapy.
• Long-term recumbency can lead to limb edema and muscle atrophy:
  • Massage to the effected limb and other forms of physical therapy Physical rehabilitation (after fracture stabilization) can prevent or help treat these complications.
• It is important to encourage the recumbent animal to begin walking again:
  • To prevent slipping, a textured non-slip surface such as concrete or soil is helpful for this exercise.
  • When the dog has deficits in its rear limbs only (paraparesis) it can be supported by a number of simple methods:
    • The dog can be grasped by the base of the tail (when minimal support is needed), or supported by a towel under the abdomen and assisted to walk.
    • Commercially made supports can be helpful and are available in a wide variety of sizes. These devices can be used on both the thoracic and pelvic limbs to provide a sling effect. Due to possible binding in the axial and groin areas, these should not be used for extended walking exercises.
    • For the animal that is reluctant to walk or has deficits in all four limbs a supportive sling, preferably on wheels, may be necessary.
  • Although not practical in all hospital settings, hydrotherapy can also be an effective method of physical therapy:
    • Swimming provides a buoyant environment for the animal to attempt movement of its limbs without having to support its full weight.
    • The warm water also promotes adequate circulation and muscle relaxation.
    • A non-slip surface such as a cage mat should be placed on the bottom of the tub or deep sink.
    • Sterile petroleum ointment should be applied over the surgical incision.
    • Rarely are wound complications such as infection noted if clean water is used at each therapy.
    • The water can be filled to a depth which provides enough support for the animal to attempt to stand on its own and encourages the animal to swim.
    • An animal should never be left unattended in water.
    • The therapist should keep his or her hands on the animal at all times to prevent slipping or attempts at jumping out.
    • A variety of children's flotation devices can be helpful in supporting the animal in the water. These range from simple inflatable toys from a local store to specially adapted canine life vests which can be purchased from water skiing or diving equipment stores. Another popular swim toy which can be found near pool accessories are long, foam rubber tubes. These can be useful as a support under the abdomen of a swimming dog and can also be assembled into a raft-like device to support a heavy or tetraparetic animal.
  • The animal's ability to urinate following spinal injury is another important factor in determining prognosis for recovery and quality of life:
    • Inability to control bladder function can have a greater influence on the dog's quality of life than the return of limb function Urinary incontinence.
    • Assessing the animal's bladder function both prior to and following spinal surgery is crucial.
    • The presence or absence of urine on the animal's bedding or in the cage, voluntary or involuntary urination and the ease or difficulty with which urine is passed should be determined.
    • The bladder should be gently palpated regularly (at least every 6 hours; more frequent in animals that are polyuric), to determine the volume of urine it contains and to establish whether or not the animal is fully emptying its bladder each time it urinates.
    • Urine left in the bladder due to inadequate bladder emptying can lead to cystitis.
    • Manual expression may be necessary every 6 hours if the animal is not able to urinate on its own.
    • Addition of phenoxybenzamine Phenoxybenzamine (0.25-0.5 mg/kg orally q8-12 h) or prazosin Prazosin (Dog: 1 mg if <15 kg bodyweight or 2 mg if >15 kg PO q8-12 h; Cat 0.25-0.5 mg PO q12-24 h) and diazepam Diazepam (0.5 mg/kg orally 20 min prior to expression) may help to reduce urethral sphincter tone and facilitate expression.

Treatment

• If the animal has been managed non-surgically, follow-up evaluations can be scheduled as necessary based upon clinical course.
• It is ideal to evaluate the animal at 3 and 6 weeks after injury to critically assess neurological progress.
• If an external support bandage has been applied, more frequent evaluations may be performed to change soiled bandages.
• Radiographic assessment of fracture healing may also be used to determine when cage-confinement or external support can be terminated.
• If healing is suspected to be complete, a gradual return to exercise should be initiated:
  • Short leash-controlled walks are begun (10-15 mins; 1-3 times per day for the first 1-2 weeks), on flat surfaces with good footing. The animal is monitored for any pain or decline in neurologic status.
  • If leash walks are tolerated, the duration and number of walks during the day can be increased over the next 2-4 weeks.
  • If the animal tolerates this exercise, the animal may have free activity after this time, providing that the activity area is enclosed (eg fenced back yard), and there is good footing.
• The animal that has had surgical fixation is treated similarly:
  • Appropriate wound management is used for the first 2 weeks.
  • If clinical improvement is noted, the aforementioned exercise scheme can be followed.
• Radiographs can be taken at least 6 weeks after surgery to assess the alignment, surgical implants and fracture healing, but are not consistently needed unless complications arise.
• Vigorous excercise that involves jumping and twisting should be avoided permanently especially in the case of luxations which will only demonstrate fibrous union rather than osseous union.

• Guarded: may have other serious injuries.
• The presence or absence of deep pain sensation seems to be an important prognostic indication.
• Deep pain negative paraplegic animals probably will not recover, especially if radiography shows overriding of the vertebrae.
• Cervical injuries are associated with a guarded to grave prognosis if the animal is tetraplegic and unable to ventilate adequately.
• The prognosis for recovery of fecal and urinary incontinence in lumbrosacral and sacrocaudal fractures is approximately 50% if there is absent anal tone and no nociception in the perineal region or the tail at the time of presentation.
• Long-term postoperative care may be significant in terms of time, money and effort. As such, thorough briefing of the client is critical.

• Neurological improvements may be slow.
• Pain should resolve quickly if surgical stabilization is performed.
• The longer the case continues without evidence of neurological recovery, the less likely recovery becomes.
• Further improvement after 4-6 weeks is unlikely to be significant.

• The animal may simply be too badly injured from the outset, and euthanasia is not an uncommon outcome to this type of injury.
• Over optimistic prognosis due to failure to detect other serious lesions.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Tatton B, Jeffery N, Holmes M (2009) Predicting recovery of urination control in cats after sacrocaudal injury: a prospective study. JSAP 50 (11), 593-596 PubMed.
• Bruce C W, Brisson B A, Gyselinck K (2008) Spinal fracture and luxation in dogs and cats: a retrospective evaluation of 95 cases. Vet Comp Orthop Traumatol 21 (3), 280-284 PubMed.
• Laverty P H et al (2004) A preliminary study of intravenous surfactants in paraplegic dogs: polymer therapy in canine related SCI. J Neruotrauma 21 (12), 1767-77 PubMed.
• Olby N J, Levine J, Harris T, Muñana K, Sheen T & Sharp N J H (2003) Long term functional outcome of dogs with severe thoracolumbar spinal cord injuries. JAVMA 222 (6), 762-769 PubMed.
• Bagley R S et al (1999) Exogenous Spinal Trauma - clinical assessment and initial mangement. Comp Contin Educ Pract Vet 21 (12), 1138-1144 VetMedResource.
• Hawthrone J C, Blevins W E, Wallace L J et al (1999) Cervical vertebral fractures in 56 dogs - A retrospective study. JAAHA 35 (2), 135-46 PubMed.
• Anderson A, Coughlan A R (1997) Sacral fractures in dogs and cats - a classification scheme and review of 51 cases. JSAP 38 (9), 404-409 PubMed.
• Bruecker K A (1996) Principles of vertebral fracture management. Semin Vet Med Surg (Small Anim) 11 (4), 259-272 PubMed.
• Quencer R M & Bunge R P (1996) The injured spinal cord - Imaging, histopathologic, clinical correlates, and basic science approaches to enhancing neural function after spinal injury. Spine 21 (18), 2064-6 PubMed.
• Coates J R, Sorjonen D C, Simpson S T, Cox N R et al (1995) Clinicopathologic effects of a 21-aminosteroid compound (U74389G) and high-dose methylprednisolone on spinal cord function after simulated spinal cord trauma. Vet Surg 24 (2), 128-39 PubMed.
• Ferguson J F (1995) What is your diagnosis? Spinal fractures. JSAP 36 (9), 381/406 PubMed.
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• Bruecker K A, Seim H B 3rd (1992) Principles of spinal fracture management. Semin Vet Med Surg (Small Anim) 7 (1), 71-84 PubMed.
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• Taylor R A (1992) Post-surgical physical therapy - The missing link. Comp Contin Ed 14 (2), 1583-94 AGRIS FAO.
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Other sources of information

• Sharp N J H, Wheeler S J (2005)Spinal trauma.In:Small Animal Surgical Disorders, Diagnosis and Surgery.2nd edn. Chapter 13, pp 281-318. Elsevier Mosby.
• Bruecker A & Seim III H B (1993)Spinal fractures and luxations.In:Texbook of Small Animal Surgery, 2nd edn. Ed D Slatter. Philadelphia: W B Saunders Co. pp 1110-1121.