Clinical Characteristics of Dogs with Progressive Myelomalacia Following Acute Intervertebral Disc Extrusion

Abstract

BackgroundProgressive myelomalacia (PMM) is a catastrophic disease associated with acute intervertebral disc extrusion (IVDE). Published data on the clinical characteristics of this disease are limited.ObjectiveTo describe the onset and progression of clinical signs of PMM in a large case cohort.AnimalsFifty‐one dogs, 18 with histopathologically confirmed PMM, 33 presumptively diagnosed based on clinical signs and diagnostic imaging.MethodsRetrospective study. Dogs with confirmed IVDE and either a histopathologic diagnosis of PMM or a high clinical suspicion were identified by medical record search. Data on nature and progression of signs were extracted.ResultsTwenty‐four of 51 dogs were Dachshunds. T12–T13 was the most common site of disc extrusion (12 of 56), and 18 of 55 of mid‐to‐caudal lumbar discs (between L3 and L6) were affected. Onset of PMM signs ranged from present at first evaluation (17/51) to 5 days after presentation, with 25 of 51 cases developing signs within 48 hours. Progression of signs from onset of PMM to euthanasia or death, excluding 7 cases euthanized at presentation, ranged from 1 to 13 days with 23 being euthanized within 3 days. Nonspecific systemic signs were documented in 30 of 51 dogs.Conclusion and Clinical ImportanceThe majority of dogs developed PMM within 2 days of presentation and was euthanized within another 3 days. However, onset can be delayed up to 5 days after presentation with progression to euthanasia taking as long as 2 weeks. Mid‐to‐caudal lumbar discs might be associated with an increased risk of PMM.

Current Approaches to the Management of Acute Thoracolumbar Disc Extrusion in Dogs

“…One retrospective study demonstrated decreased odds of successful outcome with conservative therapy, and lower owner-reported quality of life scores, with the use of corticosteroids, irrespective of dose, duration, or specific steroid administered ( 23 ). While no study provides a prospective comparison of NSAIDs vs. anti-inflammatory doses of steroids in the management of IVDE in dogs, a recent study retrospectively evaluated clinical risk factors for the development of progressive myelomalacia in deep pain negative dogs and suggested that administration of corticosteroids may have a protective effect ( 62 ). The use of steroids at anti-inflammatory doses or NSAIDs in management of canine IVDE is an area where clinical equipoise exists and while controlling for pre-treatment of dogs prior to referral would present a challenge, this question could lend itself to prospective randomized trials evaluating outcome, quality of life, and incidence of myelomalacia between the two treatments.…”

Risk factors associated with progressive myelomalacia in dogs with complete sensorimotor loss following intervertebral disc extrusion: a retrospective case-control study

“…A definitive diagnosis requires post mortem evaluation of the spinal cord, but a presumptive diagnosis with a high clinical suspicion can be made based upon neurologic examination findings corroborated with magnetic resonance imaging (MRI) characteristics [3–6]. The clinical signs consistent with PMM are a combination of complete sensorimotor loss in the pelvic limbs and the tail, loss of spinal reflexes in the pelvic limbs, loss of abdominal tone and advancement of the caudal border of the cutaneous trunci muscle reflex (CTMR) [5, 6]. As the disease spreads to the thoracic and cervical spinal cord, progression to tetraparesis, loss of reflexes in the thoracic limbs, bilateral Horner’s syndrome and respiratory distress often arise prior to death or humane euthanasia [5].…”

“…The clinical signs consistent with PMM are a combination of complete sensorimotor loss in the pelvic limbs and the tail, loss of spinal reflexes in the pelvic limbs, loss of abdominal tone and advancement of the caudal border of the cutaneous trunci muscle reflex (CTMR) [5, 6]. As the disease spreads to the thoracic and cervical spinal cord, progression to tetraparesis, loss of reflexes in the thoracic limbs, bilateral Horner’s syndrome and respiratory distress often arise prior to death or humane euthanasia [5]. Most dogs develop signs consistent with PMM within 48 h of presentation but although the majority progress and are euthanized within 3 days after onset of signs, a delayed progression can be observed [5].…”

“…As the disease spreads to the thoracic and cervical spinal cord, progression to tetraparesis, loss of reflexes in the thoracic limbs, bilateral Horner’s syndrome and respiratory distress often arise prior to death or humane euthanasia [5]. Most dogs develop signs consistent with PMM within 48 h of presentation but although the majority progress and are euthanized within 3 days after onset of signs, a delayed progression can be observed [5].…”

Intensive Functional Neurorehabilitation and Follow-up of 84 Paraplegic Dogs Affected by Intervertebral Disc Disease

“…The extrusion of disc material (Type I intervertebral disk disease, IVDD) causes contusion and compression of the spinal cord at different magnitudes in relation to the extrusion velocity and the mass of extruded disc material (Jeffery et al, 2013). Contusive events could lead to a chain of biochemical and vascular events that could produce myelomalacia under extreme conditions (Brisson, 2010;Muguet-Chanoit et al, 2012;Fingeroth et al, 2015;Castel et al, 2017). The compression could be reverted by removing disc material.…”