Retrospective analysis of spinal arachnoid cysts in 14 dogs

Spinal cord dysfunction secondary to spinal arachnoid cysts (SACs) has been reported previously in dogs. This retrospective study reviews the clinical signs, radiographic findings, and outcome after surgical resection of SACs in 14 dogs. Plain vertebral column radiographs and myelography were done in all dogs. Computed tomography (CT) was done in 7 dogs and magnetic resonance (MR) imaging in 3 dogs. Affected dogs were between 1 and 12 years of age, and 8 of 14 were Rottweilers. Abnormalities detected on neurological examination depended on the location of the SAC. Five dogs had bilobed or multiple SACs. SACs were located in the cervical vertebral column in 11 dogs and in the thoracic vertebral column in 4 dogs. All dogs had dorsally or dorsolaterally located SACs. Two dogs also had additional ventrally located SACs. Spinal cord compression secondary to intervertebral disc extrusion or protrusion was demonstrated at the site of the SACs in 2 dogs. Surgical resection of the SACs was completed in all dogs. Eleven dogs were available for follow-up. Five weeks postoperatively, 7 dogs improved in neurological function, with some residual ataxia and paresis in 6 of these dogs. Neurological function had deteriorated in 4 dogs. It was concluded from this study that Rottweilers have a higher incidence of SACs than other breeds of dog. Furthermore, bilobed or multiple SACs can occur commonly, and myelography effectively localized SACs in dogs. Surgical resection of SACs resulted in improvement in neurological function in the majority of treated dogs.     

A necrotizing meningoencephalitis of pug dogs

Clinical and pathologic features of a sporadic, necrotizing meningoencephalitis affecting adolescent and mature pug dogs are described. Many of the affected animals were closely related. Acute and chronic forms occur, with clinical signs reflecting the pathologic affinity of the disease for the cerebral hemispheres. No etiologic agent has been identified. The extensive necrosis and affinity for the cerebral hemispheres are similar to alphatype herpesvirus encephalitides of other species.     

Usefulness of a half-fourier acquisition single-shot turbo spin-echo pulse sequence in identifying arachnoid diverticula in dogs

Single-shot turbo spin-echo sequences are heavily T2-weighted sequences that are exceptionally well suited to evaluate the subarachnoid space. In the T2-weighted fast spin-echo sequences that are used routinely in spinal magnetic resonance (MR) imaging, the subarachnoid space is not well differentiated from the surrounding epidural fat, which could lead to decreased detection of lesions of the subarachnoid space such as arachnoid diverticula. Our purpose was to determine the added value of a single-shot turbo spin-echo sequence in identifying cystic lesions of the subarachnoid space in dogs. MR images of six dogs with a confirmed arachnoid diverticulum and 24 dogs with other spinal disease were included. Six observers were asked to interpret only T2-weighted images initially, and in a second session, T2-weighted and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences. The MR images were anonymized, and no signalment, history, or clinical information was provided. Without the HASTE sequences, 25% of arachnoid diverticula were identified. Adding the HASTE sequence increased the diagnosis of arachnoid diverticulum to 52.8%. The resulting difference, after adding the HASTE sequence, of 27.8% was statistically significant (P = 0.002). No false-positive diagnoses of arachnoid diverticulum were made with either sequence. Although sensitivity in this study was likely artificially low, the significantly increased detection rate of arachnoid diverticula when using HASTE imaging indicates that this sequence is a valuable addition to MR imaging protocols for the canine spine.     

Spinal arachnoid cysts in 17 dogs

The medical records of 17 dogs diagnosed with spinal arachnoid cysts at North Carolina State University Veterinary Teaching Hospital were retrospectively examined to identify trends in signalment, history, neurological status, treatment, and short- and long-term prognosis. The typical case was that of a nonpainful, progressive ataxia frequently characterized by hypermetria and incontinence. Cysts typically occurred in the dorsal subarachnoid space at the first to third cervical vertebrae of young, large-breed dogs or the caudal thoracic vertebrae of older, small-breed dogs. Although 14 of 15 dogs treated surgically did well in the short term, long-term successful outcomes were achieved in only eight of the 12 dogs that were followed for >1 year. Significant predictors of good, long-term outcome were not identified; however, factors associated with a trend toward a good outcome included <3 years of age, <4 months' duration of clinical signs, and marsupialization as the surgical technique.     

Recurrent spinal arachnoid cyst in a cat

Spinal arachnoid cysts (SACs) are uncommon expanding lesions in the spinal canal. They are rarely diagnosed in dogs, and there are only four published cases in cats. We report a case of a 12-year-old cat with recurrent signs of intermittent urinary incontinence and hind limb ataxia 2 years after surgical marsupialisation of a spinal arachnoid cyst at T11/12. Recurrence of a cyst was diagnosed by myelography. Repeated marsupialisation after laminectomy was successful and the cat recovered satisfactorily although intensive physical therapy was necessary. SACs are very rare in cats and seem to occur mainly as a secondary lesion to spinal and meningeal trauma or irritation due to bony changes of the vertebrae.     

Intradural spinal arachnoid cyst in a dog

An 8-month-old, spayed female dog was presented with signs localizing a neurologic lesion between the 3rd thoracic and 3rd lumbar vertebrae. An arachnoid cyst was diagnosed by myelography, and a dorsal laminectomy with durotomy was performed. The dog continues to do well 1-1/2 year after surgery.     

Cervical spinal arachnoid cyst in a dog

An 18-month-old, intact male Akita presented with a 12-month history of progressive ataxia, hypermetria, and loss of conscious proprioception of the thoracic and pelvic limbs. Neurological examination and myelography localized a lesion at cervical vertebrae 1 and 2 consistent with an arachnoid cyst. Hemilaminectomy and cyst fenestration led to virtually full recovery.     

Evaluation of risk and clinical outcome of mast cell tumours in pug dogs

Mast cell tumours (MCT) are common in dogs and characterized by diverse biologic behaviour. Our objective was to evaluate the risk of MCT in pugs and to describe the clinical behaviour of MCT in this breed. Data obtained from the Veterinary Medicine Database demonstrate significantly increased frequency of MCT in pugs compared with other dogs (OR = 2.28, 95% CI = 1.81–2.86). The medical records for 25 purebred pugs with a histologic diagnosis of MCT were reviewed. Multiple cutaneous tumours were documented in 14 (56 %) of the dogs. Histologic review of 64 tumours from these dogs confirmed that most tumours (94%) were low to intermediate grade. Sixty‐four per cent of these dogs are still living, while only three dogs (12%) have died due to mast cell disease. A median survival time has not been reached. The median follow‐up time is 660 days from the diagnosis of the first MCT. We conclude that MCT in pugs are relatively benign, despite the presence of multiple cutaneous tumours in most cases. Multiple tumours in breeds with predisposition to MCT may indicate separate primaries rather than advanced stage disease.     

Acquired cervical spinal arachnoid diverticulum in a cat

A one‐year‐old, female entire, domestic, shorthair cat presented with acute onset non‐ambulatory tetraparesis. Magnetic resonance imaging was consistent with a C3‐C4 acute non‐compressive nucleus pulposus extrusion and the cat was treated conservatively. The cat was able to walk after 10 days and was normal 2 months after presentation. The cat was referred five and a half years later for investigation of an insidious onset 3‐month history of ataxia and tetraparesis. Magnetic resonance imaging of the cervical spine was repeated, demonstrating a spinal arachnoid diverticulum at C3 causing marked focal compression of the spinal cord. This was treated surgically with hemilaminectomy and durectomy. The cat improved uneventfully and was discharged 12 days later.     

Thoracolumbar spinal cord compression due to vertebral process degenerative joint disease in a family of Shiloh Shepherd dogs

Five young Shiloh Shepherd Dogs (4 males and 1 female) related by a common sire were studied because of progressive pelvic limb weakness and incoordination. All dogs had a spastic paraparesis and pelvic limb ataxia consistent with an upper motor neuron and general proprioceptive lesion between spinal cord segments T3 and L3. Proliferative lesions involving one or more of the articular processes from the 11th thoracic vertebrae to the 2nd lumbar vertebra were observed on radiographs of the thoracolumbar vertebrae. Dorsal compression of the spinal cord was identified during imaging studies at these sites. Abnormalities of the synovial joints and bony proliferation of the involved articular processes were identified at postmortem examination in 2 dogs. The articular processes and associated vertebral arches protruded into the vertebral canal, indenting the dorsal surface of the spinalcord. Degenerative joint disease (DJD) was identified histologically. A compressive myelopathy was diagnosed in the spinal cord. These dogs were affected by a compressive myelopathy as a consequence of vertebral process DJD that likely has a geneticcomponent. The DJD could have been caused by a primary vertebral malformation or an injury to the processes at a young age causing malarticulation.     

Quadrigeminal cisterna arachnoid cyst diagnosed by MRI in five dogs

Arachnoid cysts of the quadrigeminal cisterna are infratentorial cystic lesions located between the collicular plate and the incisural notch of the tentorium. We report here five cases of quadrigeminal cisterna arachnoid cysts in dogs. In this study, four of the five dogs were male, three showed signs of seizures, and one dog was over 10 years of age. In two of the dogs, cysts were discovered incidentally. In previous reports, most intracranial arachnoid cysts were located in the quadrigeminal cisterna. The presence of cysts should be considered in toy breeds presenting for seizures or ataxia.     

Paintball intoxication in a pug

Objective: To describe a case of toxicity caused by oral ingestion of paintballs by a dog and how it was initially misdiagnosed as ethylene glycol intoxication due to similar clinical signs and a positive ethylene glycol blood test. Case summary: A 7 year‐old, 8.3 kg, female spayed Pug was referred for treatment of ethylene glycol (EG) toxicity. The patient was ataxic, disoriented, polyuric, polydipsic, and had a positive EG blood test. The patient was started on fomepizole therapy and intravenous fluids. Biochemical assays of the serum showed abnormalities that were not typical of EG toxicity. The following morning the patient defecated bright pink feces. The owner revealed that bright pink paint balls were present in the household when questioned. The patient completed fomepizole therapy and was discharged 40 hours after presentation with no clinical signs. Follow‐up telephone conversations found the pet to be clinically normal 2 months after discharge. New or unique information provided: This is the first known case report of paint ball intoxication in a dog that resulted in a positive EG blood test and clinical signs similar to ethylene glycol toxicity.     

Cervical spinal intradural arachnoid cysts in related,young pugs

Seven related young pugs were diagnosed with cervical spinal intradural arachnoid cysts by magnetic resonance imaging (n = 6) and myelography (n = 1). All dogs were presented with skin abrasions on their thoracic limbs and non‐painful neurological deficits, indicating a C1‐T2 myelopathy. In all six dogs examined by magnetic resonance imaging not only the spinal arachnoid cyst but also a concomitant, most likely secondary, syringohydromyelia was confirmed. Pedigree analysis suggested a genetic predisposition for spinal arachnoid cysts in this family of pugs. Generalised proprioceptive deficits more pronounced in the thoracic limbs suggesting a focal cervical spinal cord lesion, with concomitant skin abrasions on the dorsal aspect of the thoracic limbs in a young pug, should alert veterinarians to the possibility of cervical spinal arachnoid cysts.     

A potential early clinical phenotype of necrotizing meningoencephalitis in genetically at‐risk pug dogs

BackgroundNecrotizing meningoencephalitis (NME) in the pug dogs is a fatal neuroinflammatory disease associated with rapid progression and poor response to conventional immunosuppressive therapy. Diagnosis is typically made after severe neurological abnormalities have manifested.Hypothesis/ObjectivePug dogs at genetic risk for NME might manifest neurological abnormalities before developing pathognomonic clinical signs of NME.AnimalsThirty‐six pug dogs less than 4 years of age asymptomatic for NME.MethodsProspective observational cohort study with germline genome‐wide genotyping. Neurological examinations were performed 4 weeks apart to document reproducible findings of central nervous system disease. Magnetic resonance imaging, cerebrospinal fluid analysis, and testing for infectious diseases were performed in all pugs with reproducible abnormalities detected on neurological examination.ResultsThe overall risk allele frequency in this cohort was 40%; 5 (14%) dogs were high risk, 19 (53%) dogs were medium risk, and 12 (33%) dogs were low genetic risk for NME. Reproducible abnormalities detected on neurological examination were identified in 8/24 (33%) genetically at‐risk dogs and 0/12 (0%) low risk dogs. Clinical abnormalities included multifocal spinal pain in 8/8, reduced menace response in 5/8, and lateralizing postural reaction deficits in 5/8 pugs. There was a strong association between genotype risk and the presence of this clinical phenotype (P = .03).Conclusions and Clinical ImportanceOur findings suggest the presence of a novel early clinical phenotype of NME in apparently asymptomatic genetically at‐risk pugs which might be used to plan early diagnostic and therapeutic clinical trials.     

Craniotomy with cystoperitoneal shunting for treatment of intracranial arachnoid cysts in dogs

Objective— To describe a technique of decompressive craniotomy with cystoperitoneal shunt (CPS) placement for treatment of canine intracranial arachnoid cyst (IAC), and to evaluate outcome in 4 dogs. Study Design— Retrospective study. Animals— Dogs (n=4) with IAC. Methods— Medical records of dogs diagnosed with IAC by magnetic resonance imaging (MRI; 3 dogs) or computed tomography (CT; 1 dog) were evaluated. All dogs had varying degrees of neurologic dysfunction before surgery. A combined lateral (rostrotentorial)/suboccipital craniotomy was performed sacrificing the transverse sinus on the operated side. The rostral (ventricular) end of a low‐pressure valve shunt (3.0 mm outer diameter, 7.0 cm length) was placed transversely into the cyst cavity; the distal end was placed in the peritoneal cavity. All dogs were rechecked at various intervals by ≥1 of the authors either directly, by telephone consultation with owners, or both. Three dogs were imaged postoperatively (CT–1 dog; MRI–1; ultrasonography–1). Results— Intraoperative complications were limited to excessive transverse sinus hemorrhage requiring blood transfusion in 1 dog. There were no postoperative complications. Clinical signs of neurologic dysfunction resolved in 3 dogs and improved substantially in 1 dog. The latter dog required long‐term, low‐dose corticosteroid therapy. No dogs required repeat surgery. Mean follow‐up time was 23.8 months (range, 12–43 months). Collapse of the intracranial cyst was verified in 3 dogs with repeat imaging. In 2 dogs, there was no evidence of the cyst on CT or MRI; in the third dog, a small amount of fluid was demonstrated rostral to the cerebellum on ultrasonography, but there was no identifiable cyst. In 1 dog, the rostral aspect of the shunt had shifted; however, this was not associated with any clinical deterioration. Conclusion— Craniotomy with CPS placement was well tolerated and resulted in sustained improvement or resolution of dysfunction. Cyst decompression was verified in 3 dogs that were re‐imaged. None of the patients required re‐operation. Excessive transverse sinus hemorrhage is a potential danger that may necessitate blood transfusion. Other IAC patients treated with this method will need to be evaluated to fully evaluate its effectiveness. Clinical Significance— Craniotomy with CPS placement may be an effective treatment method for dogs clinically affected with IAC.     

Thoracolumbar dorsolateral laminectomy with osteotomy of the spinous process in fourteen dogs

Objective— To describe outcome after an alternative unilateral approach to the thoracolumbar spine for dorsal laminectomy.
Study Design— Retrospective clinical study.
Animals— Dogs (n=14) with thoracolumbar spinal cord compression.
Methods— Thoracolumbar spinal cord compression was lateral (6 dogs), dorsal (4), and dorsolateral (4) caused by subarachnoid (7) and synovial cysts (2) and intradural-extramedullary neoplasia (5). All dogs were treated by dorsal laminectomy with osteotomy of the spinous process using a unilateral paramedian approach. The contralateral paraspinal muscles were not stripped from the spinous process and the osteoligamentous complexes were preserved. Retraction of the spinous process and muscles to the contralateral side resulted in complete visualization of the dorsal vertebral arch thereby allowing dorsal laminectomy to be performed.
Results— No technique complications occurred. Approximately 75% exposure of the spinal cord (dorsal and lateral compartments) was achieved providing adequate visualization and treatment of the lesions. Transient deterioration of neurologic state occurred in 5 dogs because of extensive spinal cord manipulation. At long-term follow-up, 6 dogs were normal, 6 had clinical improvement, and 2 were unchanged.
Conclusion— Dorsal laminectomy after osteotomy and retraction of the spinous process may be considered in canine patients with dorsal, dorsolateral, or lateral compression to facilitate adequate decompression of the spinal cord.
Clinical Significance— This surgical technique offers an alternative approach to the thoracolumbar spine and spinal cord by a modified dorsal laminectomy that preserves the paraspinal muscle integrity on the contralateral side.