S. De Decker

Clinical evaluation of 51 dogs treated conservatively for disc-associated wobbler syndrome

OBJECTIVES To evaluate the clinical evolution and potential risk factors of 51 dogs treated conservatively for disc-associated wobbler syndrome. METHODS Medical records of dogs treated conservatively for disc-associated wobbler syndrome were reviewed, and owners were contacted regarding clinical evolution and survival of their animals. Relationships between age, treatment before diagnosis, type of neurological signs, results of medical imaging and outcome were determined. RESULTS Fifty-one dogs underwent conservative treatment for disc-associated wobbler syndrome. A successful outcome was achieved in 45 per cent (23 of 51) of the patients. Median follow-up period was 18.5 months, and median survival time was 47 months. In 85 per cent of the dogs in which euthanasia was performed because of disc-associated wobbler syndrome, this was carried out in the first year after diagnosis. Outcome score was influenced by type of neurological signs and additional radiographic and/or myelographic abnormalities. Outcome score was not significantly associated with age, number of protruded intervertebral discs, occurrence, type and results of treatment before diagnosis. CLINICAL SIGNIFICANCE Conservative treatment of disc-associated wobbler syndrome is associated with a guarded prognosis. It can be considered in cases where all four limbs are not affected and no additional radiographic and/or myelographic abnormalities are detected.

Signalment, Clinical Presentation, and Diagnostic Findings in 122 Dogs with Spinal Arachnoid Diverticula

Background Most information about spinal arachnoid diverticula (SADs) in dogs has been retrieved from relatively small case series. The aim of this study was to describe this disease in a larger number of dogs. Objectives Description of the signalment, clinical presentation, and imaging findings of a large number of dogs with SADs. Animals One hundred and twenty‐two dogs with SADs. Methods Retrospective case series study. All medical records were searched for a diagnosis of SAD. The diagnosis was made based on myelography, computed tomography myelography (CT‐m), or magnetic resonance imaging (MRI). Results In the 122 dogs, 125 SADs were identified. Sixty‐five were located in the cervical region and 60 in the thoracolumbar region. A higher body weight was significantly associated with a cervical localization of the SAD (P < .001). Ninety‐five dogs were male and 27 dogs were female. Male dogs were significantly overrepresented (P < .0001). The most commonly affected breed was the Pug dog. Previous or concurrent spinal disorders, in the near proximity of the diagnosed SAD, were seen in 26 dogs. Eight of 13 French Bulldogs and 7 of 21 Pug dogs with SADs had a previous or concurrent spinal disease, whereas other spinal disorders occurred in only 1 of 17 Rottweilers with SADs. Conclusions and Clinical Importance Pug dogs and French Bulldogs might have a predisposition for SAD development. In a large percentage of these dogs, a concurrent spinal disorder, which might predispose to SAD formation, was diagnosed. The high prevalence in male dogs warrants further investigation.

Current insights and controversies in the pathogenesis and diagnosis of disc-associated cervical spondylomyelopathy in dogs

Disc-associated cervical spondylomyelopathy (DA-CSM) is the most common cause of cervical spondylomyelopathy in dogs. In this condition, progressive caudal cervical spinal cord compression is typically caused by protrusion of one or more intervertebral discs. This disc-associated compression is sometimes seen in combination with mild vertebral abnormalities and dorsal compression resulting from ligamentum flavum hypertrophy. The intervertebral disc space between the sixth (C6) and seventh (C7) cervical vertebrae is most commonly affected. Although several large breed dogs can be affected, the adult to older dobermann is overrepresented. Clinical signs vary from cervical hyperaesthesia to tetraplegia. Dogs can present with a chronic progressive or an acute onset of clinical signs. Many aspects of this multifactorial neurological syndrome are not completely understood and are the subject of controversy and debate. Although several factors have been proposed, the underlying pathology and aetiology remain unknown. Recently, new insights have been gained in the pathogenesis, diagnosis and treatment of this challenging neurological syndrome. This review outlines current controversies and new developments concerning the pathogenesis and diagnosis of DA-CSM.

Clinical reasoning in canine spinal disease: what combination of clinical information is useful?

Spinal disease in dogs is commonly encountered in veterinary practice. Numerous diseases may cause similar clinical signs and presenting histories. The study objective was to use statistical models to identify combinations of discrete parameters from the patient signalment, history and neurological examination that could suggest the most likely diagnoses with statistical significance. A retrospective study of 500 dogs referred to the Queen Mother Hospital for Animals before June 2012 for the investigation of spinal disease was performed. Details regarding signalment, history, physical and neurological examinations, neuroanatomical localisation and imaging data were obtained. Univariate analyses of variables (breed, age, weight, onset, deterioration, pain, asymmetry, neuroanatomical localisation) were performed, and variables were retained in a multivariate logistic regression model if P<0.05. Leading diagnoses were intervertebral disc extrusion (IVDE, n=149), intervertebral disc protrusion (n=149), ischaemic myelopathy (IM, n=48) and neoplasms (n=44). Multivariate logistic regression characterised IM and acute non-compressive nucleus pulposus extrusions as the only peracute onset, non-progressive, non-painful and asymmetrical T3-L3 myelopathies. IVDE was most commonly characterised as acute onset, often deteriorating, painful and largely symmetrical T3-L3 myelopathy. This study suggests that most spinal diseases cause distinctive combinations of presenting clinical parameters (signalment, onset, deterioration, pain, asymmetry, neuroanatomical localisation). Taking particular account of these parameters may aid decision making in a clinical setting.

Risk factors for early post-operative neurological deterioration in dogs undergoing a cervical dorsal laminectomy or hemilaminectomy: 100 cases (2002–2014)

Early post-operative neurological deterioration is a well-known complication following dorsal cervical laminectomies and hemilaminectomies in dogs. This study aimed to evaluate potential risk factors for early post-operative neurological deterioration following these surgical procedures. Medical records of 100 dogs that had undergone a cervical dorsal laminectomy or hemilaminectomy between 2002 and 2014 were assessed retrospectively. Assessed variables included signalment, bodyweight, duration of clinical signs, neurological status before surgery, diagnosis, surgical site, type and extent of surgery and duration of procedure. Outcome measures were neurological status immediately following surgery and duration of hospitalisation. Univariate statistical analysis was performed to identify variables to be included in a multivariate model. Diagnoses included osseous associated cervical spondylomyelopathy (OACSM; n = 41), acute intervertebral disk extrusion (IVDE; 31), meningioma (11), spinal arachnoid diverticulum (10) and vertebral arch anomalies (7). Overall 54% (95% CI 45.25-64.75) of dogs were neurologically worse 48 h post-operatively. Multivariate statistical analysis identified four factors significantly related to early post-operative neurological outcome. Diagnoses of OACSM or meningioma were considered the strongest variables to predict early post-operative neurological deterioration, followed by higher (more severely affected) neurological grade before surgery and longer surgery time. This information can aid in the management of expectations of clinical staff and owners with dogs undergoing these surgical procedures.

Cervical Vertebral Stenosis Associated with a Vertebral Arch Anomaly in the Basset Hound

OBJECTIVES To report the clinical presentation, imaging characteristics, treatment results, and histopathological findings of a previously undescribed vertebral malformation in the Basset Hound. ANIMALS AND METHODS Retrospective case series study. Eighteen Basset Hounds presented for evaluation of a suspected cervical spinal cord problem. All dogs underwent computed tomography myelography or magnetic resonance imaging of the cervical region. RESULTS Thirteen male and 5 female Basset Hounds between 6 months and 10.8 years of age (median: 1.4 years) were studied. Clinical signs varied from cervical hyperesthesia to nonambulatory tetraparesis. Imaging demonstrated a well-defined and smooth hypertrophy of the dorsal lamina and spinous process of ≥ 2 adjacent vertebrae. Although this bony abnormality could decrease the ventrodorsal vertebral canal diameter, dorsal midline spinal cord compression was predominantly caused by ligamentum flavum hypertrophy. The articulation between C4 and C5 was most commonly affected. Three dogs were lost to follow-up, 10 dogs underwent dorsal laminectomy, and medical management was initiated in 5 dogs. Surgery resulted in a good outcome with short hospitalization times (median: 4.5 days) in all dogs, whereas medical management produced more variable results. Histopathology confirmed ligamentum flavum hypertrophy and demonstrated the fibrocartilaginous nature of this anomaly. CONCLUSIONS AND CLINICAL IMPORTANCE Dorsal lamina and spinous process hypertrophy leading to ligamentum flavum hypertrophy should be included in the differential diagnosis of Basset Hounds with cervical hyperesthesia or myelopathy. Prognosis after decompressive surgery is favorable. Although a genetic component is suspected, additional studies are needed to determine the specific etiology of this disorder.

Dorsal vertebral column abnormalities in dogs with disseminated idiopathic skeletal hyperostosis (DISH).

Although disseminated idiopathic skeletal hyperostosis (DISH) most often affects the ventral aspect of the vertebral column, this study evaluated the occurrence, nature and clinical relevance of dorsal vertebral column abnormalities in 10 dogs with DISH for which CT or MRI and a complete neurological examination were available. Dorsal vertebral column abnormalities were present in eight dogs and included articular process hypertrophy (n=7 dogs), periarticular new bone formation (n=1), pseudoarthrosis between spinous processes (n=4) and thickening of the dorsal lamina (n=4). These dorsal vertebral abnormalities caused clinically relevant vertebral canal stenosis in six dogs and were the only cause of clinical signs in four of these dogs. Although the lumbosacral joint was not affected by DISH, these six dogs demonstrated lumbosacral vertebral canal stenosis and clinical signs of cauda equina compression, which included paraparesis (n=5 dogs), lumbosacral pain (n=4), urinary incontinence (n=4), faecal incontinence (n=1) and urinary and faecal incontinence (n=1). There is a possible association between DISH and hypertrophy of dorsal vertebral structures, potentially resulting in vertebral canal stenosis. Although these changes occurred at segments fused by DISH, they predominantly affected adjacent non-affected segments.

Tethered Cord Syndrome Associated with a Thickened Filum Terminale in a Dog

A1-year-old female neutered English Cocker Spaniel was presented with a 9 months history of progressive right pelvic limb lameness. Survey radiographs, computed tomography (CT), magnetic resonance imaging (MRI), and joint taps of the pelvis, stifles, hock joints and tarsi, performed before referral, were within normal limits. Medical management with meloxicam did not result in clinical improvement. Treatment with gabapentin, initiated 7 days before presentation, resulted in improvement. General physical examination did not reveal any abnormalities. Neurological examination revealed paraparesis, right pelvic limb lameness, a low tail carriage, proprioceptive deficits expressed by delayed hopping, but intact paw placement in both pelvic limbs, a reduced withdrawal reflex in the right pelvic limb and decreased tail tone. Pain was elicited on lumbosacral palpation, dorsal extension of the tail and extension of both hips. The remainder of the neurological examination was within normal limits. Her neurological lesion was localized to the L4-S3 spinal cord segments. A complete blood count and biochemistry panel were within normal limits. After premedication with methadone (0.2 mg/kg IM) and acepromazine (0.0 1mg/kg IM), anesthesia was induced with propofol (4–6 mg/kg, IV), and maintained with sevoflurane in oxygen. MRI of the lumbar and lumbosacral vertebral column was performed with the dog in dorsal recumbency with flexed limbs (ie, frog-leg position). The imaging protocol included sagittal and transverse plane T2-weighted (repetition time (ms) (TR), echo time (ms) (TE), 3000/120), sagittal and dorsal plane T2-weighted short-tau inversion recovery (TR/TE, 3612/80), and transverse plane T2-weighted BAL TGRAD (TR/TE, 7.9/3.9) sequences. Sagittal and transverse plane T1-weighted (T1W TSE) (TR/TE, 400/8) images were acquired before and after IV injection with gadolinium contrast. MRI demonstrated possible caudodorsal displacement of the conus medullaris. Mild lumbosacral intervertebral disk protrusion was also seen (Fig 1). After MRI, a CT examination of the lumbosacral vertebral column was performed using a 16-slice scanner. After completion of the transverse CT study, sagittal and dorsal reconstructions were made. CT imaging (Fig 2) confirmed the MRI findings and did not reveal any other vertebral or spinal abnormalities. Differential diagnoses included tethered cord syndrome and dynamic lumbosacral vertebral canal stenosis. Given her initial positive response, medical management was continued with gabapentin (10mg/kg, q8h, PO), carprofen (2mg/kg, q12h, PO) and restricted exercise for 4 weeks. A re-examination 4 weeks later demonstrated progression of her clinical signs characterized by more pronounced paraparesis and right pelvic limb lameness. General anesthesia was induced and maintained with the aforementioned protocol. A standard dorsal lumbosacral laminectomy, from L7 to S2 was performed. After opening the vertebral canal, a ligamentous structure was identified between the conus medullaris and the dorsal lamina of S2, which caused caudodorsal displacement and traction of the conus medullaris (Fig 3A,B). After sectioning and sampling the distal aspect of this ligamentous structure, the conus medullaris regained a more cranial position. The wound was closed routinely. Intraoperative analgesia was provided with ketamine (loading dose of 0.5 mg/kg IV followed by a CRI at 10 lg/kg/min IV) and methadone (0.1 mg/kg q4h, IV). Postoperative analgesia consisted of a combination of methadone (0.2 mg/kg, q4h, IV), carprofen (2 mg/kg, q12h, PO) and gabapentin (10 mg/kg, q8h, PO). The dog was discharged from hospitalization 4 days after surgery. The owner was advised to provide strict rest for 4 weeks in combination with gabapentin and carprofen for 2 more weeks. From the Department of Veterinary Clinical Science and Services, (De Decker, Gregori, Kenny, Hoy, Volk); Department of Pathology and Pathogen Biology, The Royal Veterinary College, University of London, North Mymms, Hertfordshire England (Erles). Department of Veterinary Clinical Science and Services, The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Hertfordshire AL97TA, England. This case report was presented in abstract form (poster) at the 27 Symposium of the European College of Veterinary Neurology (ECVN), 18–20 September 2014, Madrid, Spain. Corresponding author: S. De Decker, Department of Veterinary Clinical Science and Services, The Royal Veterinary College, University of London, Hawkshead Lane, North Mymms, Hertfordshire AL97TA, England; e-mail: sdedecker@rvc.ac.uk. Submitted September 15, 2014; Revised October 28, 2014; Accepted November 11, 2014. Copyright

Associations Between Anesthetic Variables and Functional Outcome in Dogs With Thoracolumbar Intervertebral Disk Extrusion Undergoing Decompressive Hemilaminectomy

Background Outcome of acute experimental spinal cord injury is strongly associated with tissue perfusion and oxygenation. Cardiopulmonary depression could affect outcome in dogs undergoing general anesthesia for surgical treatment of thoracolumbar intervertebral disk extrusion (IVDE). Hypothesis/Objectives To evaluate the effects of general anesthesia on functional outcome in dogs undergoing surgery to treat thoracolumbar IVDE. Animals Eighty‐four client‐owned dogs with acute thoracolumbar IVDE treated by decompressive hemilaminectomy. Methods Exploratory, retrospective observational study. Medical records were reviewed for clinical presentation and anesthetic monitoring variables, including duration of anesthesia and surgery, hypotension, bradycardia, temperature, and respiratory parameters. Multivariable regression tree analysis was performed to explore associations between anesthetic variables and functional outcome scores after 6 weeks, as well as return to ambulatory status. Results Episodes of bradycardia (69%) and hypotension (57%) were frequent. Across all outcome measures, regression tree analysis highlighted functional grade at presentation as the primary determining factor, and among pain perception negative dogs, there was a possible association between increased duration of surgery and poorer outcome. In dogs with intact pain perception, duration of bradycardia, mean body temperature, and mean end‐tidal carbon dioxide were highlighted. Conclusions and Clinical Importance Exploratory statistical methods can facilitate hypothesis‐generating studies to inform prospective investigations in veterinary medicine. Although the mechanism is uncertain, increased duration of surgery might be associated with poorer outcome in pain perception negative dogs with thoracolumbar IVDE.

Clinical presentation, diagnostic findings and long-term survival in large breed dogs with meningoencephalitis of unknown aetiology

Although several studies indicate that meningoencephalitis of unknown aetiology (MUA) might affect every dog breed at every age, little is known about clinical presentation, diagnostic findings and long-term survival in large breed dogs. The aim of this study was therefore to compare the clinical presentation, diagnostic findings and long-term survival between large and small/medium breed dogs diagnosed with MUA. One hundred and eleven dogs met the inclusion criteria. 28 (25 per cent) dogs were considered large breed dogs compared with 83 (75 per cent) small/medium breed dogs. Large breed dogs presented significantly more often with a decreased mentation. Age, gender, duration of clinical signs prior to diagnosis, presence of seizures or cluster seizures, variables on complete blood count and cerebrospinal fluid analysis, and all variables on MRI were not significantly different between small/medium and large breed dogs. Median survival time was 281 and 106 days for the large and small/medium breed dogs, respectively, with no significant difference in survival curves for both groups. Although considered not typically affected by MUA, 25 per cent of dogs included in this study were considered large breed dogs. Therefore, MUA should be included in the differential diagnosis for large breed dogs presenting with intracranial neurological signs. If diagnosed with MUA, large breed dogs also carried a guarded prognosis.