Spinal Arachnoid Diverticula: Outcome in 96 Medically or Surgically Treated Dogs

Prevalence, clinical presentation, and etiology of myelopathies in 224 juvenile dogs

BACKGROUND

Intervertebral disc herniation is widely recognized as the most common cause of myelopathy in dogs older than 2 years; however, the prevalence of various causes of myelopathy in younger dogs has not been reported.

HYPOTHESIS/OBJECTIVES

To describe the prevalence, clinical presentation, and etiology of myelopathy in dogs aged 18 months or less. Secondarily, to investigate which clinical features were associated with each of the most common etiologies.

ANIMALS

Two hundred twenty-four dogs aged 18 months or less with myelopathy were included in the study.

METHODS

Retrospective review of clinical records from 4 referral institutions. Multivariable logistic regression analyses assessed which clinical features were associated with each diagnosis.

RESULTS

French bulldogs (n = 51, 22.8%), pugs (n = 18, 8.0%), crossbreeds (n = 12, 5.4%), and English bulldogs (n = 11, 4.9%) were the most frequently affected breeds. Overall, 31 diagnoses were reached. The 5 most frequent diagnoses were vertebral malformation (VM; n = 42, 18.8%), spinal arachnoid diverticulum (SAD; n = 28, 12.5%), traumatic fracture of the vertebral column (n = 22, 9.8%), atlantoaxial instability (n = 18, 8.0%), and osseous-associated cervical spondylomyelopathy (n = 17, 7.6%). Intervertebral disc extrusion (IVDE) accounted for 4.5% of cases (n = 10). A final diagnosis of VM was associated with younger, screw-tailed, and pug breeds with chronic signs of T3-L3 myelopathy. SAD was associated with screw-tailed and pug breeds with nonpainful clinical signs. Intervertebral disc extrusion was associated with older, screw-tailed, and pug breeds with shorter duration of clinical signs.

CONCLUSIONS AND CLINICAL IMPORTANCE

Prioritization of differential diagnoses for dogs presenting with signs of myelopathy when aged 18 months or less should differ to those for older dogs, with IVDE not the most common cause in the former.

Description and clinical relevance of the variable conformation of canine spinal arachnoid diverticula

The conformation of spinal arachnoid diverticula (SAD) and their clinical implications are poorly characterized in dogs. This retrospective cross-sectional study describes different SAD conformations in dogs and aims to identify if there is an association between SAD conformation and clinical features, localization, syringomyelia (SM) presence, concurrent vertebral condition, treatment option, and short as well as long-term outcome. Sixty-two dogs were included (12 cervical and 50 thoracolumbar SAD). All dogs with a cervical SAD had a cranial tethered conformation and were not included in the statistical analysis. Half of the dogs with a thoracolumbar SAD were cranial tethered, and the other half were caudal tethered. SM associated with SAD had a moderate prevalence in the cervical region (58.3%) and a high prevalence in the thoracolumbar region (82%). All dogs with the presence of SM and caudal tethered SAD had a cranial positioned SM, and all dogs with SM and a cranial tethered SAD had a caudal positioned SM. The SM absolute length and SM length/L2 ratio were significantly higher (P = .018, respectively) in the caudal tethered SAD compared with the cranial tethered SAD. The short-term outcome was statistically different (P = .045) between caudal and cranial tethered thoracolumbar SAD, but not the long-term outcome (P = .062). Multivariable logistic regression identified thoracolumbar caudal tethered SAD conformation had a better short-term outcome (P = 0.017, OR: 0.043, CI: 0.003-0.563), independently of SM length measurements. SAD conformation in dogs can influence SM formation. A possible link between short-term outcome and SAD conformation was found, but further research is warranted.

Vertebral and spinal malformations in small brachycephalic dog breeds: Current knowledge and remaining questions

Small brachycephalic dog breeds, such as the French bulldog, English bulldog and pug have become increasingly popular. These breeds are predisposed to a variety of vertebral and spinal malformations, including hemivertebra, caudal articular process dysplasia, transitional vertebra, cranial thoracic vertebral canal stenosis, spinal arachnoid diverticulum and meningeal fibrosis. Recent studies have provided new insights into the prevalence, anatomical characteristics, pathophysiology and treatment of these conditions. Thoracic hemivertebra, caudal articular process dysplasia, transitional vertebra, and cranial thoracic vertebral canal stenosis occur commonly in neurologically normal dogs. Although the clinical relevance of these vertebral anomalies has therefore been questioned, severe kyphosis and hemivertebra in pugs have been associated with an increased likelihood of neurological signs. Meningeal fibrosis is characterised by the formation of dense intradural fibrotic adhesions, constricting the spinal cord. This condition has been heavily associated with the pug breed. It is in pugs further common to observe multiple concurrent spinal disorder in association with chronic progressive pelvic limb gait abnormalities. This clinical presentation has been referred to as 'pug dog thoracolumbar myelopathy' and potential genetic risk factors have recently been identified. Despite our increased knowledge, many questions remain currently unanswered. This review discusses our current understanding and controversies surrounding vertebral and spinal malformations in small brachycephalic dog breeds.

An extradural cyst in a French Bulldog

CASE HISTORY

A 7-year-old, male neutered French Bulldog was referred to a specialist veterinary hospital for evaluation of progressive paraparesis of 6-months' duration. The owners reported both faecal and urinary incontinence at home.

CLINICAL FINDINGS

The dog presented with ambulatory paraparesis and pelvic limb ataxia that was more pronounced in the right pelvic limb. The pelvic limb withdrawal response and sciatic myotatic response were reduced bilaterally. Postural reaction responses were delayed in both pelvic limbs, and this was more obvious in the right pelvic limb. The anal tone and perineal sensation were normal at the time of examination.An L4-S3 myelopathy was suspected. CT of the spine revealed a compressive, bilobed, extramedullary, cyst-like structure within the vertebral canal, between L7 and S3. Surgical removal of the cyst via a L7-S1 dorsal laminectomy was performed. Histopathological examination and additional immunohistochemistry of the excised structure indicated a probable ependymal cyst with a ciliated lining. The dog recovered well post-operatively, and at follow-up 3 weeks later had some improvement of his neurological signs. The paraparesis and pelvic limb ataxia had improved; however, the remaining neurological examination was similar to the pre-surgical examination.

DIAGNOSIS

Extradural cyst.

CLINICAL RELEVANCE

Spinal cysts can contribute to clinical signs that resemble other common chronic spinal cord diseases, such as intervertebral disc disease. Therefore, this disease should be considered as a differential when dealing with cases of progressive paraparesis and pelvic limb ataxia. This case report may potentially provide opportunities in the future for further understanding of the pathogenesis, behaviour, outcomes and subclassification of spinal cysts in dogs.

Neurogenic Bladder in Dogs, Cats and Humans: A Comparative Review of Neurological Diseases

Lower urinary tract disease (LUTD) includes abnormalities in the structure and function of the bladder and the urethra. LUTD caused by neurological disease is defined neurogenic bladder (NB). The integrity of the central nervous system (CNS) and peripheral nervous system (PNS) is required to explicate normal micturition, maintaining the proper function of bladder and urethra. The location and type of neurological lesions influence the pattern of clinical manifestations, potential treatment, and prognosis. Though, in dogs and cats, spinal cord injury is considered mainly responsible for bladder and/or urethra incompetence, other disorders, congenital or acquired, involving CNS or PNS, could play a role in NB. In veterinary medicine, the information about the epidemiology, prevalence, etiopathogenesis, diagnosis and treatment of NB are scattered. The aim of this study is to provide an overview of the epidemiology, prevalence, clinical findings, diagnosis and prognosis for NB in dogs and cats compared with humans.

Retrospective evaluation of surgical outcomes after closure of durotomy in eight dogs affected by spinal subarachnoid diverticulum

Background:

Canine spinal subarachnoid diverticulum has been studied since 1968 and a few advancements have been made with regard to the treatment of this disease. Several surgical techniques have been proposed which include durectomy, fenestration, and/or marsupilization with the latter two regarded as the more favorable surgical treatments.

Aim:

In this retrospective study, we evaluated the closure of the durotomy incision in the treatment of canine spinal subarachnoid diverticulum.

Methods:

We retrospectively evaluated eight dogs with clinical signs and magnetic resonance imaging findings consistent with spinal subarachnoid diverticulum located in the cervical and thoracolumbar area. This was to determine whether the fenestration with closure of durotomy was superior to the marsupialization technique. In all dogs, fenestration and removal of subarachnoid adherences alongside closure of the durotomy were carried out.

Results:

Mild post-operative deterioration was observed in all dogs. Follow-up from 7 to 36 months indicated a satisfactory outcome.

Conclusion:

We conclude that the closure of durotomy has similar short-term and long-term outcomes compared to the previous reported studies. These results suggest that the closure of durotomy is a viable technique for spinal subarachnoid diverticulum.

Subarachnoid diverticulum associated with feline infectious peritonitis in a Siberian cat

Case summary

A 7-month-old Siberian cat was presented for investigation of acute onset multifocal neurological deficits. Neurological examination documented dull mental status and an ambulatory left hemiparesis. Serum biochemistry documented marked hyperglobulinaemia. MRI of the brain identified marked leptomeningeal contrast enhancement extending along the brainstem caudally to involve the cranial cervical spinal cord. MRI of the cervical spine further identified a subarachnoid diverticulum that extended from the level of the obex to the C2-C3 vertebrae. Cerebrospinal fluid quantitative RT-PCR was positive for the presence of feline coronavirus. Histopathology revealed pyogranulomatous meningitis and choroid plexitis, uveitis and nephritis.

Relevance and novel information

This article describes the first reported case of a subarachnoid diverticulum associated with feline infectious peritonitis.

Spinal subarachnoid diverticula in dogs: A review

Spinal subarachnoid diverticula are fluid dilations of the subarachnoid space that can cause a compressive myelopathy in dogs. These diverticula are usually associated with high motion areas in the cervical and caudal thoracic spine. The definitive etiopathogenesis has not been determined but likely involves congenital or acquired causes. Pugs, French bulldogs, and Rottweilers are overrepresented breeds. Clinical signs typically include ataxia, paresis, and upper motor neuron urinary and/or fecal incontinence; pain is a less common feature. Diagnosis is based on advanced imaging, with magnetic resonance imaging now being favored given the additional detail of the spinal cord parenchyma that can be obtained. Outcomes are better with surgical intervention than with medical therapies, though there is a lack of long-term data. No superior surgical technique has been identified, and questions remain on the significance of addressing leptomeningeal adhesions at the time of surgery. Clinical signs can recur, though not always due to recurrence of diverticulum formation, and pugs may be less likely to have a successful long-term outcome.

Extended durotomy to treat severe spinal cord injury after acute thoracolumbar disc herniation in dogs

OBJECTIVE

To report recovery of ambulation of dogs treated with extended thoracolumbar durotomy for severe spinal cord injury caused by intervertebral disc herniation.

STUDY DESIGN

Descriptive cohort.

ANIMALS

Twenty-six consecutive paraplegic dogs presented with loss of deep pain sensation after acute thoracolumbar intervertebral disc herniation.

METHODS

Each dog underwent routine diagnostic assessment and surgery for removal of extradural herniated intervertebral disc, followed by a four-vertebral body length durotomy centered on the herniated disc. Each dog was followed up until it was able to walk 10 steps without assistance or until 6 months after surgery.

RESULTS

Sixteen of 26 dogs recovered to walk unaided (all but one also recovered fecal and urinary continence), and six dogs did not; four dogs were lost to follow-up. One dog was euthanized because of signs consistent with progressive myelomalacia. There was no evidence of detrimental effects of durotomy within the period of study. Using Bayesian analysis, we found a point estimate of successful outcome of 71% with 95% credible interval from 52% to 87%.

CONCLUSION

Extended durotomy seemed to improve the outcome of dogs in our case series without increase in morbidity.

CLINICAL SIGNIFICANCE

Extended durotomy appears safe and may improve the outcome of dogs with severe thoracolumbar mixed contusion and compressive injuries associated with acute intervertebral disc extrusion.

Short- and long-term outcome and magnetic resonance imaging findings after surgical treatment of thoracolumbar spinal arachnoid diverticula in 25 Pugs

Background

There is a successful outcome after surgical management of spinal arachnoid diverticula (SAD) in up to 82% of cases.

Hypothesis/Objectives

We hypothesized that Pugs have favorable short‐term and poor long‐term prognosis after surgical treatment of thoracolumbar SAD. The aim of the present investigation was to describe clinical findings, short‐ and long‐term outcomes, and follow‐up magnetic resonance imaging (MRI) findings in Pugs with thoracolumbar SAD.

Animals

Twenty‐five client owned Pugs with 12‐month follow‐up information after surgical treatment of thoracolumbar SAD.

Methods

Multicenter retrospective case series. All medical records were searched for Pugs diagnosed with SAD. Data regarding signalment, history, surgical procedure, outcome, histopathology, and follow‐up MRI results were extracted.

Results

Mean age at presentation was 7.32 (range 2‐11) years, 80% were males. Short‐term outcome was available in 25 dogs, and improvement was confirmed in 80% of dogs. Long‐term outcome was available in 21 dogs, and deterioration was confirmed in 86% of cases, with late‐onset recurrence of clinical signs after initial postsurgical improvement affecting 85% of Pugs. A moderate correlation (r = 0.50) was found between duration of clinical signs and outcome. In 8 dogs with deteriorating clinical signs, follow‐up MRI revealed regrowth of the SAD in 2 cases, new SAD formation in 2 cases, and intramedullary T2W hyperintensity/syringomyelia in 6 cases.

Conclusions and Clinical Importance

This study suggests that Pugs with thoracolumbar SAD do not have a favorable long‐term prognosis after surgical treatment for reasons yet to be determined.

Usefulness of spinal unenhanced computed tomography and CT-myelography in the age of multidetector CT technology and magnetic resonance imaging - Preliminary considerations

Over the last decade, magnetic resonance imaging (MRI) and multidetector computed tomography (MDCT) have revolutionized diagnostic potential in small animal practice, providing adequate assessment of spinal diseases at levels comparable to that achieved in human radiology. T2-weighted MRI images are extremely sensitive to intramedullary parenchymal disorders, while balanced steady-state free precession sequences provide high-quality myelographic images of the spine without the need of intrathecal contrast medium administration. Multidetector computed tomography, with its near-isotropic spatial resolution and multiplanar reformatting of the acquired datasets, provides sufficient stratigraphic details of the spinal cord and the epidural space, facilitating the detection of compressive pathologies without the need of subarachnoid opacification. Nowadays, MDCT and low-field (LF) MRI have become fairly standard and available in academic institutions and private veterinary facilities, appearing to be valuable, complementary, and non-invasive diagnostic tools for imaging the spine. In this scenario, this clinical communication provides a series of preliminary observations that may help to reconsider the usefulness of CT-myelography in the light of its invasiveness and actual diagnostic advantages compared to MRI and unenhanced MDCT for the assessment of compressive and non-compressive spinal diseases in small animals.

High prevalence of gait abnormalities in pugs

The objective of this prospective study was to determine the prevalence of gait abnormalities in a cohort of Swedish pugs by using an owner-based questionnaire targeting signs of gait abnormality and video footage showing the dog’s gait. This study also evaluated associated conditions of abnormal gait, including other health disorders prevalent in the breed. Five hundred and fifty (550) pugs registered in the Swedish Kennel Club, of one, five and eight years of age, in 2015 and 2016, were included in the study. Gait abnormalities were reported in 30.7 per cent of the responses. In the majority of cases, the character of the described gait indicated a neurological cause for the gait abnormality. An association was observed between abnormal gait and age, with gait abnormalities being significantly more common in older pugs (P=0.004). An association was also found between abnormal gait and dyspnoea, with dyspnoea being significantly more common in pugs with gait abnormalities (P<0.0001). This study demonstrated that the prevalence of gait abnormalities was high in the Swedish pug breed and increased with age. Future studies on the mechanisms behind these gait abnormalities are warranted.