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.

A 6-year-old male castrated Greyhound was presented to the William R. Pritchard Veterinary Medical Teaching Hospital, University of California, Davis, with a 4-week history of apparent spinal pain and paraparesis. There was no improvement despite treatment consisting of oral carprofen (unknown dose) for 10 days followed by a tapering course of oral prednisone for 6 days before referral (1.2-0.2 mg/kg/d). Abnormalities on physical examination included 5% dehydration, a large flaccid bladder that was easily expressed, moderate conjunctivitis , and mild generalized patchy alopecia. On neurolog-ical examination, the dog was ambulatory with marked paraparesis and absent conscious proprioception in both pelvic limbs. The patellar, gastrocnemius, and pelvic limb withdrawal reflexes were decreased bilaterally, the cuta-neous trunci reflex was absent caudal to L4, and the perineal reflex and anal tone were absent. The tail was flaccid with intact superficial pain sensation. The dog was painful with dorsal palpation of the lumbar spine. The neurological abnormalities were consistent with an L4-Cd myelopathy. A CBC and serum biochemistry had mild abnormalities , interpreted as clinically insignificant. Urinalysis indicated a specific gravity of 1.048 and marked protein-uria (41 on sulfosalicylic acid method). Thoracic radiographs and abdominal ultrasound examination indicated no clinically relevant findings. After vertebral column radiographs, where no abnormalities were seen, two 22 G 3.5-in. spinal needles were placed, 1 at the L4-5 and 1 at the L5-6 intervertebral disc spaces, but cerebrospinal fluid (CSF) could not be obtained. CSF was collected from the cerebellomedullary cistern. A diagnostic myelogram was not performed and, therefore, magnetic resonance (MR) images of the lum-bar spinal cord followed by those of the brain were acquired with a 1.5-T scanner. a T1-weighted (T1W) images and T2-weighted (T2W) images included the L3 vertebra to the caudal vertebrae and the entire brain to the C3 vertebra. The spinal cord was enlarged and slightly elevated and dorsoventrally flattened from the L4 through the S2 vertebrae. On the T2W images, there was intramedullary hyperintensity of the lumbar and sa-cral segments of the spinal cord and the cauda equina, with partial loss of epidural fat signal and gray and white matter definition in the mid lumber region (Fig 1A). After IV contrast administration, b there was moderate parenchymal contrast enhancement and mild diffuse Fig 1. (A) T2-weighted sagittal magnetic resonance images (MRI) from dog 1. Note the intramedullary hyperintensity compared with spinal cord gray matter, loss of epidural fat signal, and gray/white matter definition. (B) T1-weighted sagittal MRI and (C) T1-weighted sagittal MRI postcontrast from dog 1. There is moderate parenchymal contrast enhancement and mild diffuse meningeal enhancement (arrow) from L4 to the conus medullaris.

A 12-year-old female spayed Labrador Retriever was presented with a history of seizures and abnormal vocalization. Approximately 1 year before presentation, multiple mammary cysts had been surgically excised. A mammary mass was noted on physical examination, and 2 separate parenchymal brain lesions were found on imaging studies. Cerebrospinal fluid (CSF) collected from the cisterna magna was analyzed, and abnormalities included moderate pleocytosis with atypical discrete round cells that occasionally formed loose clusters. The dog was euthanized, and on necropsy a primary solid mammary carcinoma was identified as well as multiple metastatic foci in the brain with diffuse meningeal involvement. The cells in the CSF had a morphologic appearance similar to the cells in the primary mammary tumor and in the metastatic tumors in the brain. On immunostaining, cells from the primary mammary tumor, the brain tumors, and the CSF expressed cytokeratin. The CSF cells did not express CD18, CD3, or CD79a. A final diagnosis of mammary carcinoma with brain metastasis and meningeal carcinomatosis was made.

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