image of Tetraparesis
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Tetraparesis can result from focal or diffuse diseases of the brainstem and spinal cord, and generalized diseases of the peripheral nervous system including diseases of the neuromuscular junction and muscle, but can also be caused by non-neurological diseases. This chapters covers clinical signs, lesion localization, pathophysiology, neurodiagnostic investigation, spinal cord diseases, lower motor neuron diseases.

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15.2 Lesion localization for tetraparesis. The brainstem, cervical spinal cord and PNS are highlighted. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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15.3 Approach to localizing the neurological signs in tetraparetic animals with a normal CN examination and mentation. Note: some animals with a generalized LMN disorder may also have CN dysfunction, especially facial and laryngeal paresis.
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15.4 Propagation of a neuronal axon potential. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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15.5 The structure of a somatic neuron. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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15.6 The structure of a peripheral nerve. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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15.7 In animals with spinal cord disease, the need for further diagnostic testing depends on the results of survey spinal radiography. CSF = cerebrospinal fluid; CT = computed tomography; MRI = magnetic resonance imaging.
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15.8 Animals with LMN signs often need an electrophysiological evaluation coupled with a nerve or muscle biopsy to determine the most appropriate treatment. ACh = acetylcholine; CSF = cerebrospinal fluid.
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15.11 Soft tissue abnormalities that may contribute to cervical stenotic myelopathy in the caudal cervical spine are shown at C5–C6. The normal relationship of the soft tissues is shown at C2–C3 and C3–C4. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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15.12 Lateral cervical radiograph and myelogram from an 8-year-old Dobermann with cervical stenotic myelopathy. Note the tipping of C6. The myelogram reveals severe compression of the spinal cord at C5–C6 and C6–C7.
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15.13 Imaging study in a 14-month-old Great Dane with ataxia and tetraparesis. The lateral myelogram does not reveal any sites of compression but the ventrodorsal view shows three sites of lateral compression of the caudal cervical spinal cord (arrowed). Transverse CT myelogram at the centre of the vertebral body at C5 showing the normal appearance of the spinal cord. Transverse CT myelogram at the level of the articular processes, highlighting the lateral compression of the spinal cord by the enlarged processes.
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15.14 T2-weighted MR images of a 7-year-old male neutered Great Dane with dorsal compressive lesions at C4–C5, C5–C6 and C6–C7. The dorsal compressive lesions (due to hypertrophied ligamentum flavum) are clearly visible on the sagittal view. Focal parenchymal damage is also visible on the sagittal view and on the axial images at C6–C7 and at C5–C6.
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15.15 Normal structure and anatomical relationship of the intervertebral disc and the pathological changes seen with disc extrusion and protrusion. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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15.16 Sagittal and axial T2-weighted MR images of a 14-year-old neutered Dachshund bitch with an acute onset of tetraparesis and neck pain. The spinal cord is deviated dorsally by herniated disc material on the sagittal view and there is a hyperintensity within the spinal cord parenchyma overlying the herniated disc. The material is clearly visible in the ventrolateral aspect of the canal on the axial image (arrowed). The disc material is isointense and hypointense compared with the spinal cord, suggesting that it is not mineralized. This was confirmed at surgery.
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15.17 Axial T2-weighted and post-gadolinium T1-weighted MR images of a 10-year-old Miniature Pinscher with an acute onset of non-ambulatory tetraparesis and pain. (a) A cyst is visible as a hyperintense structure on the ventral floor of the canal causing compression of the overlying spinal cord. (b) The contrast-enhanced capsule (arrowed) surrounding the hypointense fluid centre is visible.
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15.18 Lateral cervical radiograph of a 4-month-old Viszla with calcinosis circumscripta. Note the focus of mineralization dorsal to the atlas (arrowed).
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15.19 Ligaments of the atlas and axis vertebrae. Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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15.20 Atlantoaxial subluxation. Normal relationship of the axis (C2) to the atlas (C1) and the spinal cord. Subluxation associated with an aplastic or absent odontoid process (dens). Clinical signs may not be severe as there is minimal compression. However, concussion is always possible and can lead to severe motor and sensory dysfunction. Subluxation due to traumatic fracture. Trauma may lead to fracture of the dens but is often associated with ligament rupture. Subluxation associated with a dorsally deviated dens. Compression of the spinal cord can be exacerbated by such a subluxation. (Modified from ). Illustration created by Allison L. Wright, MS, CMI, Athens, Georgia, USA.
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15.21 An 8-month-old West Highland White Terrier with a splint placed to prevent movement of the atlantoaxial junction. A thick layer of cast padding was placed first, then a splint was modelled to run ventral to the chin, neck and sternum. This was then held in place with another layer of bandage.
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15.22 Lateral cervical radiograph of a 1-year-old Yorkshire Terrier showing surgical repair of an atlantoaxial subluxation. Two transarticular screws were placed once the subluxation was reduced. The heads of the screws are denoted with arrows in the surgical image. A cancellous bone graft was placed over the articulation between C1 and C2 (*).
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15.23 Lateral and VD (inset) postoperative radiographs of the atlantoaxial junction in a 1-year-old Toy Poodle. The atlantoaxial subluxation was initially reduced using wires around screws placed in the body of C2. Two screws were needed to correct both the dorsal and lateral deviation of C2 on C1. Two screws were placed in C1 and all five screws were covered in polymethylmethacrylate. The dog made an excellent recovery.
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15.24 Lateral cervical myelogram of a 1-year-old Labrador Retriever. The subarachnoid space is markedly dilated over C2–C3 as a result of an intra-arachnoid cyst. Sagittal T2-weighted MR image of a similar subarachnoid cyst in a 9-month-old male Bloodhound. The parenchymal hyperintensity (black arrow) suggests a wider disturbance of CSF flow than simply obstruction of the subarachnoid space (white arrow).
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15.25 Sagittal and axial (inset) T2-weighted MR images of a 5-year-old mixed-breed dog that became acutely hemiplegic following a session of rough-housing with another dog. There is a hyperintensity within the spinal cord over the C2–C3 disc space and a small amount of hyperintense material (probably hydrated nucleus pulposus) visible in the canal ventrolateral to the cord (arrowed).
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15.26 Lateral cervical radiograph of a 7-month-old Dobermann that fell from a balcony. The body of C2 is fractured and displaced dorsally, causing severe compression of the overlying spinal cord. The fracture was reduced by traction wires placed around the heads of the two screws situated in the caudal body of C2. Additional screws were placed in C1 and C3 and the construct was stabilized with polymethylmethacrylate cement.
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15.27 Sagittal T2-weighted MR image of the cervical spine of a 3-year-old Yorkshire Terrier. The dog suffered an acute onset of lateralizing signs localized to C6–T2. There is no evidence of a compressive lesion, but multifocal intraparenchymal hyperintensities are visible from C5–C7. These lesions did not enhance with contrast medium and CSF analysis was unremarkable. A presumptive diagnosis of FCE was made.
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15.30 Typical stance of a cat with sciatic neuropathy associated with diabetes mellitus.
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15.31 Muscle sample from a dog infected with . A group of tachyzoites can be seen within a myocyte (arrowed). (H&E stain; original magnification X150)



The 9-year-old male Chesapeake Bay Retriever in this video clip had scavenged rotten food from a compost heap 2 days prior to developing an ascending tetraparesis with absent reflexes and intact sensation. The dog was regurgitating and a naso-oesophageal tube was placed to keep the oesophagus empty and reduce the potential for aspiration pneumonia. (See page 295 in the Manual)

Caudal cervical spondylomyelopathy

An 8-year-old neutered Dobermann bitch showing the disconnected gait typical with a caudal cervical lesion. The thoracic limb gait is short, choppy, and at times the dog appears lame. The pelvic limb gait is ataxic with long strides. The dog is also exhibiting signs of cervical pain. Note the atrophy of the supraspinatus and infraspinatus muscles, causing the scapula spine to be prominent. (See page 276 in the Manual)

Cervical disc herniation

A 5-year-old neutered Beagle bitch with a herniated disc at C4–C5. The dog has severe neck pain, resulting in reluctance to move the neck. The head is held low due to kyphosis of the thoracolumbar spine. The sclera are visible as the animal attempts to look at the videographer without moving the neck. The dog also has obvious muscle spasms causing the ears to twitch. The dog has mild ataxia in the pelvic limbs and a short-stilted gait in the thoracic limbs. When standing, the dog tends to lift the left thoracic limb due to a nerve root signature. (See page 279 in the Manual)


The 3-year-old male Coonhound in this video clip was bitten by a raccoon 10 days prior to presentation. Note the dramatic generalized muscle atrophy and hypotonia. Spinal reflexes are reduced in all four limbs, although sensation is intact. The cranial nerves are normal. (See page 293 in the Manual)


A 9-month-old male mixed-breed dog, which had been neutered 2 weeks prior to this video clip. The dog had developed a stiff gait and dysphagia since surgery. Note the classic facial expression (risus sardonicus) associated with tetanus, with the ears drawn up. When the dog was placed on its side, it developed a dramatic increase in extensor tone in all four limbs, resulting in the typical sawhorse stance. (See page 286 in the Manual)

Tick paralysis

A 3-year-old neutered Pomeranian bitch presented with a 24-hour history of non-ambulatory flaccid tetraparesis with reduced spinal reflexes. Careful inspection of the dog identified a tick. Removal of the tick resulted in a rapid improvement within 24 hours. (See page 296 in the Manual)

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