Spinal fracture in a rabbit

4 Spinal fracture in a rabbit




INITIAL PRESENTATION


Acute onset hindlimb paralysis in a rabbit.



Introduction


It is common knowledge among veterinary practitioners that rabbits are susceptible to spinal injuries, often associated with handling incidents. Thankfully, training veterinary undergraduates in careful and appropriate handling of rabbits has ensured that this is now relatively uncommon in veterinary practices. This case outlines an unfortunate incident in a teaching hospital where the rabbit sustained a spinal fracture during clinical examination. Good client relations were paramount to a satisfactory outcome from this accident.



CASE PRESENTING SIGNS


A 7-year-old male entire Netherland dwarf cross-breed rabbit (Oryctolagus cuniculus) became acutely paralysed on both hindlimbs after handling for clinical examination and nail clipping.



Husbandry


The rabbit was housed with another male entire rabbit, and had been in the owner’s possession for 6 years. The hutch was in a shed, with access through the day to an exercise pen. The substrate was wood shavings. Several other rabbits were housed in separate hutches in the same air space. The diet offered including ad libitum hay, muesli-type commercial rabbit food, and fresh vegetables. Water was offered in a sipper bottle.



Case History


The rabbit presented at the clinic for a routine myxomatosis vaccination. The clinical examination detected overgrown nails, and consent was given for these to be trimmed. A qualified veterinary nurse restrained the rabbit while a veterinary student trimmed the nails. Although the initial examination did not reveal any locomotor deficiencies, it was noted that the rabbit was not placing his hindlimbs appropriately when returned to the carrier after the nail trim.



Clinical Examination


Examination at this point showed:


• No hindlimb movement

• No deep pain was present in either hindlimb

• A dorsal swelling was palpated in the thoraco-lumbar region of the spine.

A spinal fracture was suspected.



DIFFERENTIAL DIAGNOSES


The differentials for hindlimb paralysis are:


• Trauma: spinal fracture or luxation, intervertebral disc rupture

• Limb deformities, e.g. bilateral fractures, septic arthritis, splay leg

• Spondylosis or spondylitis, osteoarthritis

• Degenerative disc disease

• Spinal neoplasia

• Localized spinal abscess

• Infectious or inflammatory central nervous system disease, e.g. encephalitozoonosis, toxoplasmosis, neosporosis, meningitis/encephalitis

• ‘Floppy bunny syndrome’ (flaccid paralysis, of unknown aetiology)

• Congenital neurological dysfunction.

It is necessary to differentiate paralysis from paresis or reluctance to move. Aetiologies may vary for general muscular weakness:


• Central nervous system (CNS) infection (see above)

• CNS disease, e.g. brain abscess or tumour, viral haemorrhagic disease (VHD), trauma, encephalitozoonosis

• Metabolic disease (resulting in ataxia or muscular weakness), e.g. hepatic lipidosis or hypokalaemia

• Terminal disease, e.g. septicaemia, renal or hepatic failure, cardiovascular disease, starvation, intestinal obstruction, VHD, predator attack

• Cardiovascular disease

• Congenital or acquired skeletal abnormalities, e.g. splay leg (developmental condition), spondylosis, kyphosis, lordosis

• Nutritional causes, e.g. hypovitaminosis E, hypovitaminosis A

• Severe ulcerative pododermatitis.

Because of the nature of this case and the clinical findings, the main differentials considered were associated with acute trauma.



Case Work-Up



Neurological examination


This is performed similarly to other small mammals, although the flighty nature of some rabbits and their reluctance to be manipulated in certain ways reduces the comprehensiveness of the examination. For example, tests such as the wheelbarrow test (postural reaction test for strength and coordination of the forelimbs) are resented by rabbits and difficult to perform. It is also important to consider the potential for worsening of pathology if a spinal fracture is manipulated and results in further spinal cord damage.


This patient had bilateral hindlimb paralysis, lacked deep pain in either hindlimb, and had no anal tone. The panniculus reflex was present cranial to the level of the fifth lumbar vertebra, where it abruptly ceased.



Medical treatment and reassessment


Although the benefits of administering steroids in cases of spinal injury are debatable, it may be useful if given within an 8 hour period in acute cases. Alternatively or in conjunction, strict cage rest may reduce further trauma and damage. If either of these is the sole investigation, treatment response should be reassessed with regular repetition of the neurological assessment to check for any improvement. If none is noted, consideration should be given to imaging modalities to investigate further, or the animal euthanized.



Diagnosis


Acute injury causing vertebral fracture and spinal cord compression (see below for radiographs).



Anatomy and Physiology Refresher


The skeleton in the rabbit is similar to other mammals (Fig. 4.1), with 8 cervical, 12 thoracic, 7 lumbar, 4 sacral and 6 caudal vertebrae. Bone density in rabbits is relatively low, and accounts for only 6% of body mass. There is no cauda equina in rabbits; thus any injury along the vertebral column will affect the spinal cord and result in upper and lower motor neuron damage.


image

Figure 4.1 Vertebrae in the rabbit, showing the normal curvature.

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Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Spinal fracture in a rabbit

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