Ana Lucia Schild

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.

Meningoencefalite e encefalomalacia por Herpesvírus bovino-5: distribuição das lesões no sistema nervoso central de bovinos naturalmente infectados

The distribution of the histological lesions in the central nervous system (CNS) of cattle naturally infected by bovine herpes virus type-5 (BHV-5) was determined in 12 affected calves from 10 outbreaks of the disease diagnosed by the Regional Diagnostic Laboratory (LRD) at Pelotas University, from 1986 to 2003. The epidemiological data, clinical signs and duration of clinical course were obtained from the files of LRD. Transversal sections were performed at different levels in 10% formalin-fixed CNS. The sections were made in the frontal, parietal, temporal e occipital lobes of the telencephalic hemispheres, basal ganglia and internal capsule, thalamus, anterior colliculus, pons, cerebellar peduncles, cerebellum, medulla oblongata and cervical spinal cord. Paraffin embedded tissues were sectioned and stained with hematoxylin and eosin. The severity and distribution of the inflammatory and malacic lesions were evaluated in all sections. These lesions were related with the epidemiological and clinical aspects of the disease. The outbreaks of the disease were observed in different seasons of the year. Affected animals were 2 to 24-month-old, of different breeds and both sexes. Gross lesions characterized by yellow and depressed areas in the cerebral cortex were observed in five calves. In two of them, similar lesions were additionally observed in thalamus, basal nuclei, and internal capsule. Congestion and multifocal hemorrhages were observed in most cases. The histological lesions were characterized by non-suppurative meningoencephalitis in all sections of CNS, but more severe in the frontal cortex. Focal or widespread malacia with infiltration of Gitter cells were observed in all sections of cerebral cortex, basal ganglia, internal capsule, and thalamus. In some cases mild malacia was also observed in the rostral colliculi, pons, medulla, cerebellum and cervical spinal cord. Intranuclear inclusion bodies were seen in all cases studied; they were frequent in regions of the cerebral cortex near mild to moderate inflammatory or malacic lesions. In two cases the inclusion bodies were also seen in the basal ganglia and thalamus. The severity of the histological lesions was not proportional with the clinical course of the disease. The presence of lesions of malacia in different regions of the CNS, an aspect not mentioned in most reports of BHV-5 infections, could be due to variable pathogenicity of different virus isolates. Alternatively, it is possible that BHV-5 encephalitis occurs due to the reactivation of the virus in cattle previously affected by polioencefalomacia; this last sequence of events was already demonstrated experimentally by our research group.

Mycotoxicoses of ruminants and horses

In the current study, mycotoxicoses of ruminants and horses are reviewed, with an emphasis on the occurrence of these diseases in South America. The main mycotoxicoses observed in grazing cattle include intoxications by indole-diterpenoid mycotoxins (Paspalum spp. contaminated by Claviceps paspali, Lolium perenne infected by Neotyphodium lolii, Cynodon dactylon infected by Claviceps cynodontis, and Poa huecu), gangrenous ergotism and dysthermic syndrome (hyperthermia) caused by Festuca arundinacea (syn. Festuca elatior) infected by Neotyphodium coenophialum (syn. Acremonium coenophialum), and photosensitization in pastures contaminated by toxigenic Pithomyces chartarum. Other mycotoxicoses in grazing cattle include slaframine toxicity in clover pastures infected by Rhizoctonia leguminicola and diplodiosis in cattle grazing in corn stubbles. The mycotoxicoses caused by contaminated concentrated food or byproducts in cattle include poisoning by toxins of Aspergillus clavatus, which contaminate barley or sugar beetroot by-products, gangrenous ergotism or dysthermic syndrome caused by wheat bran or wheat screenings contaminated with Claviceps purpurea, and acute respiratory distress caused by damaged sweet potatoes (Ipomoea batatas). The main mycotoxicosis of horses is leukoencephalomalacia caused by the fumonisins B1 and B2 produced by Fusarium spp. Poisoning by C. purpurea and F. elatior infected by N. coenophialum has also been reported as a cause of agalactia and neonatal mortality in mares. Slaframine toxicosis caused by the ingestion of alfalfa hay contaminated by R. leguminicola has also been reported in horses.

Tristeza parasitária bovina na região sul do Rio Grande do Sul: estudo retrospectivo de 1978-2005

A retrospective study of tick fever was made, which occurred from 1978-2005 in southern Rio Grande do Sul in the influence area of the Regional Diagnostic Laboratory of the Federal University of Pelotas. From 4,884 cattle specimens, sent by practitioners or which were from necropsies performed at the Diagnostic Laboratory, 231 (4.7%) were diagnosed as tick fever. Data from 221 of those outbreaks were analyzed. Ninety one (41.1%) outbreaks were caused by Babesia bovis, 11 (4.9%) by Babesia bigemina, and 65 (29.41%) by Anaplasma marginale. In other 33 (14.93%) outbreaks of babesiosis there is no information if the disease was caused by B. bovis or B. bigemina, and 21 (9.5%) outbreaks were caused by mixed infection of A. marginale and B. bovis or B. bigemina. Mean morbidity, mortality, and letality rates in 149 outbreaks were 11.17%, 6.81%, and 70.04%, respectively. Most outbreaks occurred during summer (January-March) and autumn (April-June), mainly in 1 to 3-year-old cattle. Clinical signs were depression, weakness, fallen ears, fever, and weight loss. Low packed cell volume values were always found. Hemoglobinury was observed in babesiosis. Neurological signs characterized by gait alterations, muscular tremors, aggressiveness and falling down with tonic and clonic convulsions were observed in babesiosis by B. bovis. The main gross lesions were anemia, jaundice, splenomegaly, hepatomegaly, yellow liver and cardiac hemorrhages. Hemoglobinury was observed in babesiosis, and congestion of the cerebral cortex in babesiosis by B. bovis. It is concluded that B. bovis is the main agent causing thick fever in southern Rio Grande do Sul. In that region with a cattle population of 2,630,000 heads the annual losses due to tick fever can be estimated in 6,220 cattle or US

Neoplasias do trato alimentar superior de bovinos associadas ao consumo espontâneo de samambaia (Pteridium aquilinum)

1,623,000.00. Preventive measures to diminish tick fever losses in the region are necessary.

Febre catarral maligna em bovinos no Rio Grande do Sul: epidemiologia, sinais clínicos e patologia

Foram estudados 30 bovinos com neoplasias no trato alimentar superior (TAS) associadas ao consumo espontâneo de samambaia (Pteridium aquilinum) provenientes de 27 propriedades rurais, sendo 23 no municipio de Jaguari e quatro em Nova Esperanca de Sul, Rio Grande do Sul. A populacao bovina total das 27 propriedades em que ocorreram os casos era de 1.090 bovinos e havia quantidade abundante de samambaia nas areas de pastoreio dos animais. Vinte e seis bovinos eram vacas e quatro eram machos castrados. A idade variou de tres a 13 anos, sendo o maior numero de casos entre sete e oito anos (46,6%). Os sinais clinicos observados incluiram emagrecimento progressivo, atonia ruminal, tosse, disfagia, regurgitacao, halitose, diarreia e timpanismo. Outros sinais clinicos menos frequentes foram apetite seletivo, dispneia e salivacao. Dois bovinos tiveram morte espontânea e 28 foram submetidos a eutanasia in extremis e necropsiados. Os principais achados macroscopicos e histologicos observados nos 30 bovinos localizavam-se nos mesmos locais do TAS e consistiam de papilomas, papilomas em transformacao para carcinomas de celulas escamosas (CCEs) e CCEs. Vinte e nove bovinos tinham papilomas de diversos tamanhos, sendo a quantidade variavel entre leve (45%), moderada (38%) e acentuada (17%). Nos papilomas examinados microscopicamente, foram observadas tres fases de desenvolvimento: a) fase inicial de crescimento; b) fase de desenvolvimento; e c) fase de regressao; essa ultima era caracterizada por infiltrados linfocitarios nos eixos fibrovasculares de sustentacao. Em 16 bovinos, o exame histologico de lesoes macroscopicas compativeis com papilomas, porem alguns deles apresentando-se mais arredondados, com projecoes digitiformes atenuadas ou ulceradas, revelou a transformacao maligna desses papilomas em CCEs. Os CCEs eram unicos (12/30) ou multiplos (18/30) e variaram quanto ao grau de diferenciacao celular entre bem diferenciados, moderadamente diferenciados ou pouco diferenciados. Quando a distribuicao dos CCEs de maior extensao foi agrupada em regioes cranial (base da lingua, faringe/orofaringe, epiglote), media (tercos cranial, medio e caudal do esofago) e caudal (entrada do rumen e rumen) do TAS, observou-se que a localizacao era cranial em 39% dos casos, media em 16%, e caudal em 45%. Utilizando-se esse mesmo criterio de agrupamento, porem considerando o numero total de vezes em que CCEs (de extensoes variadas) foram diagnosticados nas regioes cranial, media e caudal, os numeros alteraram-se para 34%, 26% e 40%, respectivamente. Metastases de CCEs para linfonodos regionais e outros orgaos como figado e pulmao foram observadas em 18/30 bovinos. A tecnica de imunoistoquimica para citoqueratina foi realizada em cortes selecionados de CCEs e metastases, observando-se celulas fortemente positivas nos CCEs bem e moderadamente diferenciados, e fraca imunomarcacao nos pouco diferenciados. As evidencias epidemiologicas e histomorfologicas relatadas neste estudo reforcam as observacoes de uma estreita correlacao entre a infeccao pelo papilomavirus bovino tipo 4, causador da papilomatose digestiva, e a co-carcinogenese quimica dos principios toxicos da samambaia na patogenese dos CCEs do TAS de bovinos.

Poisoning by Amorimia (Mascagnia) sepium in sheep in northern Brazil.

The epidemiology, clinical signs, necropsy and histopathological findings in cases of malignant catarrhal fever (MCF) occurring in cattle from 15 farms in Rio Grande do Sul, Brazil, from 1973 to 2003, are described. In 9 instances (60%) the disease occurred as sporadic cases affecting 1-3 cattle whereas in six farms (40%) MCF occurred as epizootics involving several cattle in each affected herd. Morbidity rates ranged from 2.4% to 20% and lethality rates were 83.3% and 100%. Cattle of all ages and both sexes were affected. Where the information was available (9 farms) sheep were in contact with affected cattle and cases of MCF occurred more frequently in spring and summer. Clinical courses were acute or subacute and clinical signs included fever, nasal and ocular discharges, conjunctivitis, drooling, hematuria, necrosis and blunting of buccal papillae, enlargement of lymph nodes, diarrhea and neurological disturbances. Necropsy findings included opaque corneas, reddening, erosions and ulcerations in several mucous membranes of the alimentary, respiratory and urogenital tracts, and the conjunctiva; enlargement and haemorrhage of lymph nodes and multiple white foci in the renal cortices and in the hepatic portal triads. Crustous dermatitis was observed in some cases. Main histopathological findings included vasculitis, necrosis of the surface epithelia and accumulation of inflammatory cells in several organs. Vasculitis were associated with fibrinoid necrosis of the medial layer of arteries and inflammatory cells included lymphoblasts, lymphocytes, plasma cells and macrophages.

A Comparative Study of the Histopathology and Immunohistochemistry of Pythiosis in Horses, Dogs and Cattle

The aim of this study was to determine the cause of sudden deaths in sheep in the Anari Valley of the state of Rondônia, in northern Brazil. In one outbreak, sheep were placed in an area where the owner had cut Amorimia (Mascagnia) sepium and let it dry for two days. Fourteen out of 35 sheep died with few outward clinical signs observed over a period of about 10 h after the ingestion of the dry plant. Dry A. sepium was administered experimentally to 9 sheep. Five died after the ingestion of single doses of 3-6.6 g/kg body weight (bw). Two sheep died after the ingestion of total doses of 6.4-31 g/kg bw over the course of 4 and 5 days, respectively, and one died after being treated with 33 daily doses of 0.56 g/kg bw. Six sheep died during exercise, and three died without exercise. Clinical signs were anorexia, muscular tremors, dyspnea, jugular engorgement, tachycardia, apathy, opisthotonos, foam in the nose, and recumbency. One sheep, which ingested a single dose of 1 g/kg bw, was not affected. The main macroscopic lesion was pulmonary edema. Histologic examination of the heart revealed degeneration and necrosis of cardiomyocytes, as well as multifocal inflammatory infiltrate of mononuclear cells. Fibrosis, neovascularization and infiltration by mononuclear inflammatory cells were observed in the sheep that ingested the plant for 33 days. Vacuolar-hydropic degeneration was observed in the epithelial cells of renal tubules of four sheep. It is concluded that A. sepium is responsible for sudden deaths in sheep.

Enfermidades do sistema nervoso dos ruminantes no sul do Rio Grande do Sul

Twenty-one cases of pythiosis in horses (n = 10), dogs (n = 9) and cattle (n = 2) were investigated. The aetiology in all cases was confirmed by immunohistochemistry. Data related to the clinical course and outcome and localization of the lesions were obtained from pathology reports. The equine lesions consisted of fibrotic tissue with multiple, often coalescing, areas of immature granulation tissue encircling eosinophilic cores. Affected dogs had gastrointestinal and/or cutaneous lesions with either or both of a granulomatous/pyogranulomatous or necrotizing eosinophilic inflammatory reaction. In cattle, cutaneous lesions were characterized by multifocal to coalescing granulomas with surrounding fibrosis. The number of intralesional hyphae, the distribution of hyphae, the presence of angioinvasion and the nature of the local inflammatory reactions were associated with the different types of lesions observed.

Bovine Focal Proliferative Fibrogranulomatous Panniculitis (Lechiguana) Associated with Pasteurella granulomatis

The main epidemiological, clinical and pathologic aspects of the diseases of the nervous system in cattle in Southern Rio Grande do Sul are described, including, the following conditions: cerebellar abiotrophy; cerebellar hypoplasia; congenital hypermetria; arthrogryposis; congenital hypomyelinogenesis; brain abscess; listeriose; tetanus; botulism; focal symmetrical encephalomalacia; rabies; leucosis; encephalitis by Herpesvirus Bovine-5; bovino malignant catarrh; intoxications by Solanum fastigiatum, Claviceps paspali, Halimium brasiliense, Diplodia maydis, and Ramaria flavo-brunnescens; hepatoencephalopaty caused by Senecio spp. and Echium plantagineum; ketosis; coenurosis; and spinal syndrome.