Aline Rodrigues

Neuropathology of Naturally Occurring Trypanosoma evansi Infection of Horses

The clinical signs and pathology of the central nervous system in 9 horses with naturally occurring neurologic disease due to Trypanosoma evansi are described. The clinical course was 2 to 20 days; clinical signs included marked ataxia, blindness, head tilt and circling, hyperexcitability, obtundity, proprioceptive deficits, head pressing, and paddling movements. Grossly, asymmetric leukoencephalomalacia with yellowish discoloration of white matter and flattening of the gyri were observed in the brain of 7 of 9 horses. Histologically, all 9 horses had necrotizing encephalitis that was most severe in the white matter, with edema, demyelination, and lymphoplasmacytic perivascular cuffs. Mild to moderate meningitis or meningomyelitis was observed in the spinal cord of 5 of 7 horses. T. evansi was detected immunohistochemically in the perivascular spaces and neuropil of formalin-fixed, paraffin-embedded brain tissue in 8 of 9 horses.

Intoxicação por Solanum fastigiatum (Solanaceae) em bovinos: epidemiologia, sinais clínicos e morfometria das lesões cerebelares

Nineteen cases of Solanum fastigiatum (Solanaceae) poisoning in cattle from three municipalites in the State of Rio Grande do Sul, Brazil, occurring from 2003 to 2005, are described. Morbidity and mortality rates were respectively 6.7% and 3.4%. Average age of affected cattle was five-year-old (2 to 8-year-old) and duration of clinical courses was 3-18 months. Clinical signs observed in all affected cattle were cerebellar deficits characterized by hypermetry, incoordination, falls, muscle tremors, transitory seizures and wide base stance. One affected bovine had encephalic traumatic subdural hemorrhage and another had gross atrophy of the cerebellum. Histologically, lesions were restricted to the cerebellum and consisted of partial or complete vacuolation of the perikaria of Purkinje neurons with occasional axonal spheroids in the granular cell layer and in the white matter of the cerebellum. In advanced cases there were extensive loss of cerebellar Purkinje neurons and proliferation of the Bergmanns glia. The morphometric evaluation of the numbers of Purkinje neurons and of the thickness of the cerebellar molecular layer indicated decreased numbers of Purkinje neurons with consequent decrease in the molecular layer thickness.

Babesiose cerebral em bovinos: 20 casos

In a retrospective study carried out in 1,071 necropsies of cattle, 20 cases of cerebral babesiosis were found. All the cases were confirmed by examination of tissue smears from telencephalic cortex. Most of these cases occurred in the summer in adult cattle of European breeds and their crosses. Clinical signs included neurological disturbances, hemoglobinuria, anorexia, fever, tachycardia, tachypnea and drop in milk yield. Blood cell counts performed in five affected cattle revelead marked regenerative anemia with an average of 20% of Babesia bovis parasitized erythrocytes. At necropsy of all cases the gray matter of the telencephalic and cerebellar cortices and of the basal ganglia consistently had a typically pink-cherry discoloration due to sequestration of red blood cells in brain capillaries. Both in nervous tissue smears and in histological preparations, it was observed that the red blood cells that clogged the capillaries of the gray matter contained organisms with morphology compatible with B. bovis. Other necropsy findings included red urine, dark-red kidneys, enlarged liver and spleen, red-orange discoloration of the liver, icterus, epicardial and endocardial hemorrhages, and congestion and edema of mesenteric lymph nodes.

OSP-Immunofluorescent remyelinating oligodendrocytes in the brainstem of toxically-demyelinated Wistar rats.

Central nervous system (CNS) remyelination following toxically-induced demyelination is a well known process. Oligodendrocytes constitute the bulk of the myelinating cells in the brain whereas Schwann cells overwhelm oligodendrocytes numbers in spinal cord remyelination. Despite the common knowledge of these facts, we still do not know completely the origin of both remyelinating cells. The present study investigated the participation of mature oligodendrocytes in remyelination after ethidium-bromide (EB) induced demyelination in the brainstem of normal and cyclosporin A-immunosuppressed Wistar rats. Thirty adult female rats were divided into three experimental groups. In group 1 the rats received a single intracisternal injection of 10 microL of 0.1% ethidium bromide (EB) in 0.9% saline (n=10); in group 2 the rats received the EB injection while immunosuppressed with cyclosporin A (n=10); in group 3 the rats received a single 10 microL injection of 0.9% saline while treated with cyclosporin A. The rats were killed at 15, 21 and 31 days after injection. Within the EB lesions, from 15 days onward many cells within the periphery of the lesions stained positive for OSP (oligodendrocyte specific protein) a marker for mature oligodendrocytes and myelin. This cell marking signals that, at least, part of the process of repairing the myelin sheaths is carried out by mature cells of the oligodendrocyte lineage.

Miocardiopatia crônica e degeneração esponjosa do encéfalo em ovinos intoxicados experimentalmente por Ateleia glazioviana

Fifteen mature crossbred sheep were fed different daily amounts (2.5-35g kg-1 bw) of the fresh green leaves of Ateleia glazioviana for different periods of time (1-24 days). One sheep was not fed the plant and served as a control. All 16 sheep were euthanatized at different stages of the experiment, necropsied, and several organs, including heart and brain were evaluated histologically. Samples of five brain regions from three affected sheep were evaluated by electron microscopy. Clinical signs observed in three sheep included depression, anorexia, general weakness, staggering gait and prolonged recumbency. One sheep had signs of congestive heart failure. Necropsy findings included subcutaneous dependent edema and edema of the body cavities in two sheep and nutmeg liver in one. Histopathological findings included degeneration, necrosis and interstitial fibrosis in the myocardium of four sheep and vacuolation of cerebral white matter (spongy degeneration, status spongiosus) in 10 sheep, although this latter change were marked only in two of those 10. The ultrastructure of the brain lesion was morphologically consistent with that found in diseases grouped as spongiform myelinopathies in which vacuolation of the myelin occurs in the absence of significant myelin breakdown or phagocytosis. The morphology and pathogenesis of the chronic cardiomyopathy and of the cerebral spongy degeneration in affected sheep in this experiment are discussed and compared with other similar conditions in domestic ruminants.

Harpejamento em eqüinos no Rio Grande do Sul

The epidemiology, clinical, gross and histological findings of cases of stringhalt occurring in horses from eight farms in six counties in the State of Rio Grande do Sul, Brazil from 2000-2005 are reported. At least 10 horses were affected. Ages of affected horses were 1-13 years (average 6.2 years) and 1-2 horses were affected in each farm. Factors that might have influenced the appearance of the disease included dearth of forage due to insufficient rainfall. The presence of the plant Hypochaeris radicata, often implicated as a cause of stringhalt in horses, was observed in the pasture of three out of five evaluated farms and in six of these farms the pasture was poor due to scarse precipitation. Estimated morbidity was 17.3% and lethality was close to zero although two horses were euthanatized for necropsy. Characteristic clinical signs included excessive flexion of the stifle and hock joints, impaired ambulation and bunny hop-type of gait. Clinical disease was graded by number scores from 1-5, higher numbers indicating increasing severity. Three horses were graded as 1, one horse as 2, three horses as 3, one horse as 4 and two horses as 5. Treatment with phenytoin in two horses and with phenytoin and tenectomy in another one did not result in amelioration of the clinical signs. Four out of ten clinical examined horses with stringhalt recovered with no treatment within 2-4 months of clinical disease and four affected horses did not recover even after 9-17 months of clinical disease, when they were lastly examined. Necropsy findings included atrophy of skeletal muscle of the large muscular groups which was confirmed histologically. Histological evaluation of peripheral nerves of one of the euthanatized horses revealed reduction or absence of myelinated fibers. Ultrastructural findings included signs of demyelination, regeneration and remyelination of peripheral nerves.

Carcinossarcoma tireoidiano em um cão

A two year-old female mongrel dog was presented with dysphagia and focal swelling at the thyroid region. Two masses were surgically removed from that site. The dog died a few days after surgery and it was not submitted to necropsy. The diagnosis of thyroid carcinosarcoma was based on malignant epithelial and mesenchymal cell components of the neoplasm and confirmed by immunohistochemistry for cytokeratin and vimentin, respectively. The thyroid origin was confirmed based on the positive immunostaining for thyroglobulin on the follicular epithelial cells and colloid. This is a neoplasm rarely diagnosed in dogs.