Resumo: As neoplasias no sistema nervoso central (SNC) de animais de companhia são frequentemente diagnosticadas, no entanto dados sobre prevalência são escassos. O objetivo deste estudo foi avaliar retrospectivamente a ocorrência de neoplasias primárias de SNC em cães atendidos em um Hospital-Escola Veterinário e descrever aspectos clínicos, histopatológicos e imuno-histoquímicos dos tumores mais frequentes. Quatorze casos (prevalência de 0,27%) de neoplasias primárias de SNC foram identificados no período de 1998 a 2013 e destes, 11 tiveram o diagnóstico de meningiomas. A idade média dos animais com meningioma foi 10 anos, sendo machos (7/11) e a raça Boxer (3/11) os mais afetados. Sete meningiomas eram espinhais e quatro intracranianos, sendo os principais sinais clínicos alteração na locomoção e convulsões, respectivamente. Metástase pulmonar ocorreu em dois casos. Em seis animais com meningioma espinhal foi realizada a mielografia, sendo que em um também foi realizada a tomografia. Em todos os casos os exames foram efetivos na visualização de desvio ou interrupção da coluna de contraste, com alterações sugestivas da presença de massa. Em cinco animais realizou-se cirurgia exploratória visando a confirmação da suspeita clínica ou retirada da massa, sendo que a sobrevida variou de 85 a 960 dias. Na avaliação histopatológica, os meningiomas foram classificados em transicional (4/11), meningotelial (2/11), papilar (2/11), angiomatoso (1/11), microcístico (1/11) e anaplásico (1/11). Destes, oito (8/11) apresentaram marcação positiva para tricrômio de Masson e um para vermelho congo nas técnicas histoquímicas. No painel imuno-histoquímico, todos os casos apresentaram imunomarcação positiva para vimentina, mas imunomarcação negativa para fator VIII e p53. A imunomarcação para S100 (6/11), GFAP (5/11) e pancitoqueratina (3/11) foi de intensidade variável. Na graduação histológica, dez meningiomas eram grau I e um grau III. O índice médio de proliferação celular foi de 3,2 figuras de mitose e 3,4% avaliando a expressão de Ki-67. Os resultados confirmaram que os meningiomas são a neoplasia primária de SNC mais prevalente em cães, com variação nos subtipos histológicos. A caracterização histoquímica e imuno-histoquímica contribuiu com a determinação do diagnóstico, no entanto, estudos envolvendo a expressão de outros genes são necessários para auxiliar no prognóstico dessas neoplasias.

Background: Various diseases can cause spinal cord disorders in dogs including neoplasia of the nervous system, which are more common in mature and older animals. Some breeds, as brachycephalics, are more predisposed for certain types of tumors. Spinal neoplasia can be categorized as primary or secondary tumors, and still can be grouped in extradural, intradural/extramedullary or intramedullary. The aim of this study was to investigate the signalment, neurological syndrome, type and source of the mass, presence of metastases, and clinical outcomes in 28 dogs diagnosed with spinal tumors.Materials, Methods & Results: This study included 28 dogs, and in 20 cases, spinal neoplasia was confirmed by necropsy, biopsy, histopathology, and immunohistochemistry. In the other eight animals, the presumptive diagnosis was based on clinical and neurological signs and by observing changes in plain radiographs of the spine, chest radiographs, and myelography. The location of the lesion was established as cervical, cervicothoracic, thoracolumbar, or lumbosacral, and the lesion was determined to be multifocal when clinical signs appeared in more than one location. Spinal cord injury was additionally classified as unilateral, bilateral, symmetrical, or asymmetrical. The following complementary examinations were performed based on the clinical suspicion, indications, and availability of the owner: complete blood count, serum biochemical profile, urinalysis, spinal radiography, cerebrospinal fluid analysis (CSF), myelography, abdominal ultrasound, thoracic X-ray to determine metastases, and Computed Tomography. CSF was collected and analyzed in seven animals, and pleocytosis with a predominance of lymphocytes was found in two cases. Decompression and exploratory surgeries were performed in six dogs to confirm the suspected diagnosis and collect tissues for histopathology. The final diagnosis was made by histopathological examination of the tissue obtained by excisional biopsy or necropsy after the death of the animal or euthanasia. In eight cases, the neoplasia type could not be confirmed as the owner did not provide consent to perform exploratory surgery or necropsy. The dogs most affected were poodles (17.85%) and boxers (17.85%), between the ages of 5 and 10 years, and 67.85% of the cases were female dogs. The thoracolumbar region was the most affected (50%). Metastatic spinal tumors predominated; especially those originating in the mammary gland (38.46%) and on the skin (34.61%), and among the primary neoplasms, meningiomas predominated. The clinical course in relation to the onset of symptoms of neurological dysfunction, until death or euthanasia, ranged from 1-170 days, with an average 42 days of survival.Discussion: The results differ from previous studies, in which the number of male and female dogs with neoplasms in the CNS was the same, as in the present study female dogs were more affected. Unlike other studies, metastatic spinal tumors predominated. After the diagnosis, the survival was short and this may be due to the fact that most dogs in this study already had more than one system affected, and consequently showed significant changes related to systemic metastases during the onset of the neurological symptoms. The surgical treatment presented variable results, and the results observed after surgical resection of neoplasms vary due to the location in relation to the spinal cord, neoplasm type, severity of the clinical signs, and possibility of removal along with margin without causing spinal instability. In dogs with spinal disorders, the veterinary practitioner should suspect cancer, especially if there is a history of excision of neoplasms in other systems.

Background: Spinal neoplasms are classified into extradural, intradural/extramedullary or intramedullary. Intradural/extramedullary tumors include meningiomas and nerve sheath tumors, which arise from meninges or peripheral nerves around the spinal cord. Clinical signs are related to dysfunction of the involved nerve and include pain, nerve root signature and atrophy. Osteochondromas are benign tumors located within the bone, on its surface or in extra-osseous regions, when they are classified as soft tissue osteochondoma. The aim of this study is to describe a case of an osteochondroma in a nervous root of the cauda equina in a dog, whose surgical resection allowed the resolution of the clinical signs.Case: A 12-year-old, male, Labrador Retriever dog, was presented with a 40-day history of progressive, painful, pelvic limb paresis, with no improvement when treated with analgesics and acupuncture. Neurological abnormalities included paraparesis, sometimes worse in the left pelvic limb, that was carried flexed at the level of the stifle, hindlimb atrophy, decreased interdigital reflexes and pain in the lumbar spinal region, mainly over L6 vertebra. Results of blood count and serum biochemical analysis were unremarkable. Computed tomography (CT) of the lumbosacral area was performed and the evaluation of images in transverse and reconstructed dorsal and sagittal planes allowed the visualization of a hyperattenuating and calcified round structure with 8 mm x 6 mm, in the left side of vertebral canal, at the level of caudal epiphysis of L6. Lumbosacral (L7-S1) CT abnormalities, as subchondral sclerosis, mild disc margin bulging, spondylosis deformans and foraminal proliferation were also observed but were considered clinically insignificant. Then, a dorsal L6 laminectomy was performed and after opening of the vertebral canal it was observed the presence of an ovoid mass, in the left side of the medullary cone, measuring approximately 0.9 cm in length, originating from a sacral nerve root. This structure was excised and submitted to histopathological evaluation. The dog improved after surgery without any complications, and neurological functions were gradually recovered. The histopathology of the mass was confirmed as an osteochondroma.Discussion: The history and neurologic examination findings as well the improvement after surgery were compatible with the lesion visualized by TC in L6, rather than the degenerative changes in L7-S1. Regarding the position of the mass, the main differential would be nerve sheath tumor, one of the most common types of primary neoplasia of the peripheral nervous system, however in a CT study in dogs with brachial plexus and nerve roots neoplasms, calcification of the tumor was not observed. Most of benign cartilaginous tumors of soft tissue are chondromas/osteochondromas, and this lesion should not be confused with multiple osteochondroma or multiple cartilaginous exostoses, which have been reported as multifocal, proliferative lesions involving the surface of ribs, vertebrae and pelvis of young dogs. If this lesion is unique, it is called osteochondroma. There are two reports of chondromas into the first lumbar vertebrae of dogs, with adherence to the floor of the vertebral canal and one report of an osteochondroma originated from the left pedicle of T11 in a cat. Radiculopathy and myelopathy caused by osteochondromas inside the spine are rare in humans and description of this tumor arising from nerve roots were not found in the veterinary literature. Probably the origin of the mass was metaplasia of the meninges surrounding the nervous root. In conclusion, neurological examination, CT and surgical exploration allowed the diagnosis and removal of a soft tissue osteochondroma, a rare benign tumor, with good patient recovery.

Background: Canine transmissible venereal tumor (TVT) is a round-cell tumor of dogs, which occurs by cell transplantation. It is usually located on the external genitalia, and is transmitted by coitus. It may occasionally be acquired by sniffng or licking the genitalia of an affected animal. Lesions may be present in the other parts of the body, such as the skin, rectum,and nasal or oral cavities. Metastasis of the TVT is uncommon, mainly occurring in immunocompromised dogs. It may affect organs such as the liver, spleen, kidney, lung, and musculature, and rarely, may be detected in the central nervous system. In this report, we describe the occurrence of a TVT causing spinal cord compression in a dog, and the results of its treatment with hemilaminectomy and chemotherapy.Case: A six-year-old male Dalmatian dog was referred to a veterinary teaching hospital with nonspecifc abdominal pain. Laboratory examination showed no abnormalities; survey radiography revealed a moderate fecal retention. The dog received painkillers and dietary guidelines. However, the patient was brought again to the veterinary teaching hospital nine dayslater with paraplegia, worse in the left limb than in the right, but with normal nociception. There was a cutaneous trunci reflex cut-off at the T10 vertebra, also worse on left side than on right, along with spinal thoracolumbar hyperesthesia. During endotracheal intubation for general anesthesia for performing a cerebrospinal fluid tap and myelography, a small mass was observed in the palatine tonsil, a sample of which was collected for cytological analysis. The cerebrospinal fluid examination showed albuminocytologic dissociation, and myelography revealed an asymmetrical epidural compression over the T8 vertebra. Surgery was performed with a lateral approach to the T8 vertebra, and a 3-cm epidural brown mass was found, which was completely excised and subjected to histopathological examination. The histopathological fndings of the mass excised from the spine revealed neoplastic proliferation of poorly differentiated, round tumor cells with large, round, central or peripheral nuclei, and slightly eosinophilic, occasionally vacuolar cytoplasm. The propagating cells formed groups separated by a delicate fbrovascular stroma, consistent with the histopathology of TVT. Upon immuno histochemical staining, the neoplastic cells were found to be positive for MHC II, CD45RA, and lysozyme, but negative for cytokeratin, CD3, CD20, and CD117. The cytological examination of the tonsillar mass confrmed TVT. The dog was treated with vincristine, but after the third cycle the treatment was discontinued due to the choice of the owner. A year after the treatment, the dog presents only a mild spinal ataxia.Discussion: Tumor cells can be transmitted through genital mucous membrane-contact at coitus. Hence, the TVT lesions are often located on the external genitalia, but this was not observed in this case. Non-cutaneous metastases, which have an incidence of about 1%, can occur on the lips and tonsils, as was observed in the present case, or in the inguinal lymphnodes, liver, kidneys, mesentery, bones, eye, brain, and abdominal cavity. The pathological characteristics of TVT is quite variable and depends on the host immune response; however, there was no evidence of immunosuppression or malnutrition in the present case. The patient might have acquired the neoplasia in the oral cavity probably from licking or sniffng the preputial or vaginal discharges of an infected dog, and therefore, the primary tumor was probably the one in the tonsil,which later metastasized to the spine. This case presents an atypically located TVT, without genital occurrence, that was successfully treated by surgery and chemotherapy. This report also indicates that TVT is also an important differential diagnosis of spinal neoplasia.Keywords: spinal neoplasms, canine transmissible venereal tumor, treatment.