Background: Intracranial meningiomas are the most common primary brain tumors in dogs. Classification of meningiomas by tumor grade and subtype has not been reported, and the value of magnetic resonance imaging (MRI) characteristics for predicting tumor subtype and grade has not been investigated.Hypothesis: Canine intracranial meningiomas are a heterogenous group of tumors with differing histological subtypes and grades. Prediction of histopathological classification is possible based on MRI characteristics.Animals: One hundred and twelve dogs with a histological diagnosis of intracranial meningioma. Methods: Retrospective observational study.Results: Meningiomas were overrepresented in the Golden Retriever and Boxer breeds with no sex predilection. The incidence of specific tumor grades was 56% benign (Grade I), 43% atypical (Grade II), and 1% malignant (Grade III). Grade I histological subtypes included meningothelial (43%), transitional (40%), microcystic (8%), psammomatous (6%), and angiomatous (3%). No statistically significant (P o .05) associations were found among tumor subtype or grade and any of the MRI features studied.Conclusions and Clinical Importance: Meningiomas in dogs differ from their counterparts in humans mainly in their higher incidence of atypical (Grade II) tumors observed. MRI characteristics do not allow for prediction of meningioma subtype or grade, emphasizing the necessity of histopathology for antemortem diagnosis. The higher incidence of atypical tumors in dogs may contribute to the poorer therapeutic response in dogs with meningiomas as compared with the response in humans with meningiomas.

Background: Choroid plexus tumors (CPTs) comprise approximately 10% of all primary brain tumors in dogs. The clinical utility of magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) analysis, or both in the presumptive diagnosis of CPTs has not been determined.Objectives: To report MRI and CSF findings in dogs with CPT and determine if there are distinguishing features that allow clinical discrimination between the tumor grades.Animals: Fifty-six client-owned dogs with naturally occurring CPT. Methods: Retrospective case series. The inclusion criterion was histologically confirmed CPT. Blinded review of cranial MRI and cisternal CSF analysis was performed.Results: Thirty-six of 56 dogs had a choroid plexus carcinoma (CPC) and 20 had a choroid plexus papilloma (CPP). Golden Retrievers were overrepresented compared with the hospital population (frequency 3.7 times that expected, confidence interval 95% 5 2.0-6.7, P o .0002). Median CSF protein concentration in CPCs (108 mg/dL, range 27-380 mg/dL) was significantly higher than in CPPs (34 mg/dL, range 32-80 mg/dL) (P 5 .002). Only dogs with CPCs had a CSF protein concentration 480 mg/dL. Cytological evidence of malignancy in CSF was seen in 7 of 15 CPCs. Only CPCs had evidence of intraventricular or subarachnoid metastases on MRI.Conclusions and Clinical Importance: MRI, CSF analysis or both can help to differentiate between CPPs and CPCs, and may provide valuable prognostic and pretreatment information.

Background: Cryptococcus spp. is a fungal pathogen with a predilection for the central nervous system (CNS). Objectives: To compare the clinical, advanced imaging, and neuropathologic findings in dogs and cats with CNS cryptococcosis, and to evaluate outcome of treatment in these animals.Animals: Twenty-six cats and 21 dogs with CNS cryptococcosis. Methods: Medical records were reviewed for clinical findings and results of CNS imaging. Archived cerebrospinal fluid and CNS tissue specimens were reviewed for pathology. Findings in cats were compared with those in dogs and the effects of variables on survival were determined by survival curve analysis.Results: When present, pain was localized to the cervical region in dogs and was generalized or localized to the thoracolumbar spine or pelvic limbs in cats. Magnetic resonance imaging (MRI) findings were variable but correlated with CNS histopathological findings of meningitis, meningitis with gelatinous pseudocyst formation, and granulomatous mass lesions. Peripherally enhancing brain lesions were seen only in cats. Histopathologically, the inflammatory response was milder in cats compared with dogs. Remissions of !1 year occurred in 32% of treated animals. Altered mentation was associated with negative outcome. Glucocorticoid use after diagnosis was associated with improved survival in the first 10 days.Conclusions and Clinical Importance: Lesions seen on MRI reflected neuropathological findings and were similar to those reported in human patients. The immune response to infection may differ between cats and dogs, or relate to the infecting cryptococcal species. Long-term (46 month median survival time) survival may be possible in animals surviving !4 days after diagnosis.

Objective-To characterize the clinical signs, diagnostic and surgical findings, and outcome in dogs with spinal epidural empyema (SEE). Study Design-Retrospective study. Animals-Seven dogs. Methods-Dogs with SEE between 1992 and 2001 were identified from a computerized medical record system. Inclusion criteria were: neurologic examination, vertebral column radiographs, myelography, antimicrobial culture and susceptibility of material collected surgically from the vertebral canal, a definitive diagnosis of SEE confirmed by surgery, and microscopic examination of tissue from the vertebral canal. Results-Common signs were lethargy, fever, anorexia, apparent spinal pain, and paraparesis/plegia. Common laboratory abnormalities were peripheral neutrophilia, and neutrophilic pleocytosis in cerebrospinal fluid (CSF). Three dogs had concurrent discospondylitis and 1 of these had vertebral luxation. On myelography, extradural spinal cord compression was focal (2 dogs), multifocal (3), or diffuse (2). Bacteria were isolated not from CSF but from blood, surgical site, pleural fluid, or urine in 6 dogs. Dogs were administered antibiotics and had surgical decompression by hemilaminectomy. Five dogs improved neurologically and had a good long-term outcome. Two dogs were euthanatized, 1 because of worsening of neurologic signs and pneumonia, and the other because of herniation of a cervical intervertebral disc 1 month postoperatively, unrelated to the SEE. Conclusion-Dogs with SEE may have a good outcome when treated by surgical decompression and antibiotic administration. Clinical Relevance-SEE should be included in a list of possible causes for dogs with fever, apparent spinal pain, and myelopathy. r

Background: Meningioma is the most common primary intraspinal nervous system tumor in dogs. Clinical findings, clinicopathologic data, and treatment of these tumors have been reported sporadically, but little information is available regarding cerebrospinal fluid (CSF) analysis, histologic tumor grade, or efficacy of radiation therapy as an adjunct to cytoreductive surgery. Animals: Dogs with histologically confirmed intraspinal meningiomas (n = 34). Methods: A retrospective study of dogs with intraspinal meningiomas between 1984 and 2006 was carried out. Signalment, historical information, physical examination, clinicopathologic data, radiation therapy protocols, surgery reports, and all available images were reviewed. All tumors were histologically classified and graded as defined by the international World Health Organization classification scheme for central nervous system tumors. Results: Intraspinal mengiomas in dogs are most common in the cervical spinal cord but can be found throughout the neuraxis. Location is correlated with histologic grade, with grade I tumors more likely to be in the cervical region than grade II tumors. Myelography generally shows an intradural extramedullary compressive lesion. On magnetic resonance imaging, the masses are strongly and uniformly contrast enhancing and a dural tail often is present. CSF analysis usually shows increased protein concentration with mild to moderate mixed pleocytosis. Surgical resection is an effective means of improving neurologic status, and adjunctive radiation therapy may lead to an improved outcome. Conclusions and Clinical Importance: Biopsy is necessary for definitive diagnosis, but imaging and CSF analysis can suggest a diagnosis of meningioma. Treatment of meningiomas with surgery and radiation therapy can result in a fair to excellent prognosis.