Spongy Myelinopathy in Newborn Beef Calves Associated with Consumption of Corn Infected with Stenocarpella maydis.

Stillbirth and perinatal mortality with neurological signs and lesions were diagnosed in two calves following ingestion by their dams of corn infected with Stenocarpella maydis during the third trimester of gestation. Grossly, the brain and spinal cord were unremarkable. Microscopically, diffuse severe status spongiosis of the white matter was detected in the cerebral hemispheres, brainstem, spinal cord and cerebellum. To the best of our knowledge this is the first pathological description of congenital disease in calves associated with the consumption of S. maydis-infected corn; the findings resemble those reported for the naturally occurring and experimentally induced disease in lambs.

Frequency of Neospora caninum infections in beef cow-calf operations under extensive management.

The aim of this study was to evaluate the frequencies of Neospora caninum horizontal and vertical transmissions in beef cow-calf operations under three different extensive management systems: group A: 0.75 head per hectare pasturing on natural grass; group B: 1.1 head per hectare on natural grass and improved cultured pastures; and group C: 2 head per hectare on natural grass, improved cultured pasture and whole corn silage. Serum samples from 72 multiparous cows assigned to each beef cow-calf operations were obtained every 3 months during 2 years. A group of 30 replacement heifers from each group were tested similarly since they were 10-21 months old. Twenty four, 20 and 34 calves from groups A, B and C respectively, were bled before colostrum intake and again 6 months later. The samples were analyzed by indirect fluorescence antibody test (IFAT) for detection of total IgG against N. caninum at a serological titre ≥ 200 for multiparous cows and replacement heifers, and a serological titre ≥ 25 for calves. Serum samples from seropositive cows were assessed by ELISA to evaluate the avidity of their specific antibodies. There were no differences in the proportion of seropositive cows from groups A, B and C at the beginning of the trial (p>0.05). Interestingly, the lowest serological titres in seropositive cows from all groups were observed during the first trimester (p<0.05). Although seropositive cows had medium to high avidity antibodies, suggesting chronic infection; seroconversion associated with low antibody avidity was found in 2, 3 and 3 seropositive cows from groups A, B and C. All replacement heifers remained seronegative. No abortions were recorded but 2, 1, and 2 calves from groups A, B and C were seropositive before colostrum intake, respectively. Seropositive calves born from cows having intermediate or high avidity remained with the same serostatus at 6 months of age. Even under varying extensive management conditions, both N. caninum horizontal and vertical transmission methods do occur in beef cow-calf operations.

Risk factors associated with Neospora caninum infections in cattle in Argentina.

From 2003 through 2007, serum samples from 5594 dairy and beef heifers and cows in Argentina were assessed to quantify the association between presence of Neospora caninum antibodies and history of abortion, type of exploitation, and age category of animals. Animals with a history of abortion were 85% more likely (P<0.01) to be positive to N. caninum than animals without a record of abortion. For a given category (age) of animals, being in a dairy operation increased the odds of being N. caninum-positive. Replacement dairy heifers were 76% more likely (P<0.01) to be N. caninum-positive than beef cows. These results suggest that postnatal exposure may be more frequent in dairy operations than in beef herds and provide insight into the epidemiology of the disease in one of the most important livestock production regions of the world.

Retrospective study of bovine neonatal mortality: cases reported from INTA Balcarce, Argentina.

A retrospective study was performed on 169 beef and dairy calves aged from 1 to 7 days old submitted to the Diagnostic Laboratories at INTA Balcarce, Argentina. Bacterial culture was performed for aerobic and microaerophilic organisms. Samples from spleen and lymph nodes, and peripheral blood mononuclear cells were also cultured for viral isolation on cell culture. Bovine rotavirus was detected by direct-ELISA. Multiple tissue samples were fixed in 10% formalin, routinely processed and Stained with hematoxylin and eosin for microscopic examination. Etiological diagnosis was made in 70 of the 169 calves. Infectious agents were identified in 49 cases, the most common being Escherichia coli. When the histopathological examination was performed in cases with undetermined diagnosis, it was noted that 44 specimens had histological lesions, which suggested the presence of an infectious agent. In order to characterize the causes of bovine neonatal mortality, the protocols and methodology should be improved in further works.

Retrospective study of bovine neonatal mortality: cases reported from INTA Balcarce, Argentina / Estudio retrospectivo de mortalidad neonatal bovina: Casos hallados en INTA-Balcarce, Argentina

A retrospective study was performed on 169 beef and dairy calves aged from 1 to 7 days old submitted to the Diagnostic Laboratories at INTA Balcarce, Argentina. Bacterial culture was performed for aerobic and microaerophilic organisms. Samples from spleen and lymph nodes, and peripheral blood mononuclear cells were also cultured for viral isolation on cell culture. Bovine rotavirus was detected by direct-ELISA. Multiple tissue samples were fixed in 10% formalin, routinely processed and stained with hematoxylin and eosin for microscopic examination. Etiological diagnosis was made in 70 of the 169 calves. Infectious agents were identified in 49 cases, the most common being Escherichia coli. When the histopathological examination was performed in cases with undetermined diagnosis, it was noted that 44 specimens had histological lesions, which suggested the presence of an infectious agent. In order to characterize the causes of bovine neonatal mortality, the protocols and methodology should be improved in further works.

Se realizó un estudio restrospectivo en 169 terneros muertos 1 a 7 días después del nacimiento pertenecientes a rodeos para carne y leche, remitidos a los Laboratorios de Diagnóstico del INTA Balcarce, Argentina. Para detectar organismos aeróbicos y microaerófilos se realizó el cultivo bacteriano. Para el aislamiento viral sobre cultivo celular, se recolectaron muestras de bazo, ganglios linfáticos y sangre periférica. El rotavirus bovino fue identificado por ELISA directo. Se efectuó el examen microscópico de diferentes tejidos, los cuales fueron fijados en formol al 10%, procesados y teñidos con hematoxilina y eosina. Se obtuvo un diagnóstico etiológico en 70 de los 169 terneros. Se identificaron agentes infecciosos en 49 casos, siendo el más común Escherichia coli. En los casos con diagnóstico indeterminado, el examen histopatológico realizado determinó que 44 especímenes poseían lesiones compatibles con la presencia de agentes infecciosos. Es necesario mejorar los protocolos y las metodologías de trabajo a los fines de caracterizar las causas de mortalidad neonatal en bovinos.

The role of Neospora caninum and Toxoplasma gondii in spontaneous bovine abortion in Argentina.

The aim of the present work was to evaluate the role of Neospora caninum and Toxoplasma gondii infections in spontaneous bovine abortions in Argentina. Based on histopathological results, 70 presumptive cases of apicomplexan protozoal abortion from a total of 666 cases of spontaneous bovine abortion submitted to the National Institute of Agrarian Technology, Balcarce, from 1999 to 2007 were included in this study. N. caninum infection was diagnosed by an indirect fluorescent antibody test (IFAT), by immunohistochemistry (IHC) and by nested-PCR. T. gondii infection also was diagnosed by nested-PCR. DNA from fetuses was extracted primarily from CNS tissues. Heart, liver, muscle and/or placenta were processed when nervous tissue was not available. Sixty-six (9.9%) fetuses were positive by at least one technique (IFAT, IHC or nested-PCR) for N. caninum infection. Overall, there was poor agreement among results obtained by these diagnostic techniques. In contrast, no Toxoplasma-infection was detected in any aborted bovine fetus.

Diplodia maydis: a cause of death of cattle in Argentina.

CASE HISTORY: This report describes an outbreak of high mortality of heifers after they consumed harvested maize fields parasitised with the fungus Diplodia maydis. CLINICAL FINDINGS: Clinical signs observed were generalised muscle tremors, incoordination, ataxic hindquarters, paralysis and death. The morbidity of the outbreak was 27/500 (5.4 %) and mortality 10/27 (37%). No gross lesions were observed, however histopathological examination revealed moderate to severe degeneration of myelin shafts in the white matter of the cerebellum. Diplodia maydis infection of maize was identified from visual characteristics of mycelia and pycnidia. DIAGNOSIS: Diplodia toxicity (diplodiosis). CLINICAL RELEVANCE: This is the first description of the poisoning of cattle by maize contaminated with D. maydis in Argentina, where feeding cattle on harvested maize fields is common practice. It is possible this disease could occur in other countries, like New Zealand, where this fungus is known to be present.

Aetiology of bovine abortion in Argentina.

Necropsies were performed on 354 fetuses from dairy and beef herds submitted from 1994 to 2000 to the diagnostic laboratories at Instituto Nacional de Tecnología Agropecuaria, Balcarce, Argentina. Samples from the fetuses were examined for pathogenic organisms and processed for microscopic examination. An aetiological diagnosis was made for 161 (45.5%) of the fetuses. No diagnosis was made for 193 (54.5%) fetuses. Infectious agents were isolated from 122 (34.4%) of the fetuses, bacterial agents being involved in 80 (22.6%) of these. The most common bacterial agents isolated from the fetuses were Brucella abortus in 28 fetuses, Campylobacter fetus in 26 cases, and Escherichia coli in 9 cases. Bovine herpesvirus and bovine viral diarrhoea virus were found in 9 and 6 cases, respectively. Neospora caninum was detected by an immunohistochemical technique in 26 cases (7.3%). Congenital abnormalities, dystocia and mummifications were found in 8, 19 and 11 cases, respectively.

[Retrospective analysis of cases with a diagnosis of cerebrocortical necrosis and its relation with type 5 bovine herpesvirus]. / Análisis retrospectivo de casos con diagnóstico de necrosis cerebrocortical y su relación con herpesvirus bovino tipo 5.

In order to demonstrate the association of bovine herpesvirus type 5 (BHV-5) and cerebrocortical necrosis (CCN), 89 such cases were examined in cattle from three regions of Buenos Aires Province, Argentina, registered between 1970-1999. Hematoxylin-eosin staining and BHV-5 in situ hybridization were performed on paraffin-embedded neural tissues. The severity of microscopic lesions was scored according to a 0-3 scale. Morbidity, mortality and lethality rates between groups depending on age and regions were determined. The highest prevalence of CCN was detected between 1979 and 1984, particularly during the spring. Differences in morbidity and mortality rates between groups of age and regions were not detected (P > 0.05). Amaurosis (48%), ptyalism (42%), circling (40%), ataxia (36%) and bruxism (37%) were frequently observed. Lesions were predominantly found in anterior and posterior cortex (90.6%) and diencephalon (36.5%). Meningitis and perivascular cuffing (94.4%) and focal (78%) or diffuse (73%) gliosis were predominant in cerebrum. Focal necrosis was observed in 66.6% of cases. BHV-5 was isolated from 9/19 cases since 1992 and BHV-5 DNA was detected by in situ hybridization in 3/9 cases. No virus was identified in brain tissues with severe lesions. These findings indicate the association of BHV-5 in neurological disease previously reported as CCN.

Análisis retrospectivo de casos con diagnóstico de necrosis cerebrocortical y su relación con herpesvirus bovino tipo 5 / Retrospective study of archive cases of cerebrocortical necrosis and their relationship with bovine herpesvirus type 5

A los fines de establecer la asociación entre herpesvirus bovino tipo 5 (HVB-5) y la necrosis cerebrocortical (NCC) se analizaron 89 casos bovinos de tres regiones de Buenos Aires registrados entre 1970-1999. El tejido nervioso fue teñido con hematoxilina-eosina o hibridización in situ para cADN-BHV-5. Las lesiones se clasificaron en una escala subjetiva de 0-3. La mayor prevalencia fue entre 1979-1984, principalmente en primavera, no existiendo diferencias (P>0,05) en las tasas de morbilidad y mortalidad entre grupos etarios, sexo, raza, sistemas de producción y regiones. Amaurosis (48 por ciento), ptialismo (42 por ciento), torneo (40 por ciento), ataxia (36 por ciento) y bruxismo (37 por ciento) fueron los síntomas más observados. Las lesiones estuvieron distribuidas en corteza anterior y posterior (90,6 por ciento) y diencéfalo (36,5 por ciento). Meningitis y manguitos perivasculares (94,4 por ciento) y gliosis difusa (77,5 por ciento) o focal (73 por ciento) fueron los hallazgos predominantes en el cerebro. Se observaron focos de necrosis en el 66,6 porciento de los casos. HVB-5 fue aislado en 9/19 casos a partir de 1992 y cADN-HVB-5 fue detectado en 3/9 casos. La identificación viral en casos con lesiones severas resultó negativa. La correspondencia de NCC con aislamiento viral de bovinos con similares características clínico-epidemiológicas permiten concluir la asociación del HVB-5 y lesiones de NCC.

Demonstration of Listeria monocytogenes by immunohistochemistry in formalin-fixed brain tissues from natural cases of ovine and bovine encephalitis.

In the present work, evidence of Listeria monocytogenes antigens based on the avidin-biotin complex (ABC) immunoperoxidase technique was performed on formalin-fixed central nervous system tissues (CNS) from a total of 23 natural cases of encephalitis (four ovine and 19 bovine). Listeria monocytogenes serotype 4 was isolated from 10 of 17 cultured specimens. Meningoencephalitis characterized by focal necrosis, microabscesses, perivascular cuffing, and gliosis with presence of macrophages and/or neutrophils was observed at histological examination. Positive L. monocytogenes antigens were successfully identified by immunohistochemistry (IHC) in the CNS of all 23 cases. Paraffin-embedded tissues assayed were stored up for 17 years. Morbidity of the outbreaks was between 0.3-3% and 0.1-1% for ovine and bovine cases, respectively. In all the ovine cases, flocks involved were under extensive grazing conditions. In nine of the 19 bovine cases (47.3%), supplementation with corn silage was used. The ABC test can help as a practical tool for the diagnosis of natural cases of L. monocytogenes encephalitis on formalin-fixed specimens from ovine and bovine.

Pyrrolizidine alkaloidosis in Argentinian cattle caused by Senecio selloi.

A herd of 135 Aberdeen Angus cows were grazing on pastures containing abundant Senecio selloi in the eastern region of Buenos Aires Province, Argentina. Some undiagnosed deaths were observed during 1989. In 1990 the death count raised to 38 animals, all of them showing the same clinical signs and gross and histopathological lesions. The time from the start of signs to death varied from 2 to 6 d. The most conspicuous signs were distention of the abdominal cavity and moderate icterus of mucous membranes. At necropsy, large amounts of fluid were in the abdominal cavity, there were lesions in the digestive tract, kidneys and mesenteric lymph nodes, and the liver was enlarged and fibrous. Histopathology showed the hepatic parenchyma replaced by fibrous tissue with marked megalocytosis. The signs and lesions were consistent with those produced by pyrrolizidine alkaloids. An abundance of Senecio selloi resulted in a diagnosis of poisoning from this plant. This is the first report of toxicity due to this plant species in Argentina.

Ryegrass staggers in heifers: a new mycotoxicosis in Argentina.

Aberdeen Angus (AA) and crossbred AA x Hereford 8-9 mo old heifers (560 animals) showed a typical perennial ryegrass (PRG) staggers syndrome after grazing 26 d in a 25-hectare paddock of pure Lolium perenne. Effects were observed in about 50% of the herd. When forced to move, the animals showed incoordination, weakening of the forelimbs, falling on the chest and neck, and moving in this position during the first steps before recovering a normal gait. In severely affected animals all of the 4 limbs had extreme rigidity. All the affected animals had generalized tremors. Twelve days after removal from this pasture the animals had no symptoms. The symptoms described, the pasture conditions (mostly PRG stubble and short PRG green plants in slow growth), a positive mouse bioassay of extracts obtained from the basal part of the PRG plants, and the microscopic finding of Acremonium lolii hyphae in the leaf sheaths of the same plant material produced diagnostic evidence to confirm this as a PRG staggers case, the first reported in Argentina.

Neuropathological effects and deaths of cattle and sheep in Argentina from Phalaris angusta.

Neuropathological disorders and mortality occurred in cattle and sheep grazing P angusta. This native plant of South America is frequently found as a good quality component of natural pastures. Cattle and sheep feeding in pastures where P angusta was dominant started dying or showing signs 3 to 5 d after rain-falls started following a period of drought. Some animals died suddenly, while others nervous effects( incoordination, inability to walk normal, recumbency) and death for up to 2 w after the beginning of the signs. Postmortem findings were bilaterally symmetrical, greenish pigmented areas in the grey matter of the brain stem and diencephalon. A greenish tinge was also noted between the cortex and the medulla of the kidneys. Granules of a brown pigment were noted within the cytoplasm of neurons. An alkaloid substance was detected in the plant. Morbidity was 2.3 to 10.5% in herds B and A, and 0 to 3.4% in flocks D and C, respectively. Mortality was 0.8 to 1.0% in herds B and C, and 3.4 to 11.7% in flocks D and C, respectively. P angusta behaves, in terms of toxicity, as other Phalaris spp. Its widespread distribution in areas of extensive grazing poses a threat to cattle and sheep production in Argentina.

Lack of effect of a diet containing zearalenone on spermatogenesis in rams.

Six breeding rams were fed a diet containing 12 mg of zearalenone daily for eight weeks. A control group of six rams was fed a diet free of zearalenone. The weekly production of spermatozoa of both groups was measured during the period of administration of zearalenone and for six weeks after the administration of zearalenone ceased. Semen production was measured in terms of the volume of ejaculate and its concentration, and the motility and abnormalities in the spermatozoa. The feeding of zearalenone had no significant effects on any of these measurements.

An outbreak of Vicia villosa (hairy vetch) poisoning in grazing Aberdeen Angus bulls in Argentina.

Vicia villosa (hairy vetch) is used as a forage source in some cattle-producing areas in Argentina. The plant had no previous reports of toxicity in this country. A herd of 33 Aberdeen Angus bulls grazed during 20 days in October on a pasture composed mainly of hairy vetch. Eight animals developed conjunctivitis, rinitis, dermatitis, loss of hair and fever. All of them died within 15 d after the development of signs with a marked loss of body condition. No more animals became sick 5 d after the removal of the herd from the pasture. Serum parameters tested (calcium, phosphorus, magnesium, GOT, alfa-GT and bilirubin) enlarged liver and spleen, generalized hemorrhage in the abomasum, dilated kidneys and multiple pale areas on the heart. Severe necrotizing granulomatous myocarditis, interstitial nephritis, and necrotizing cholangitis were the most striking microscopic changes. Close observation of animals feeding on pastures in which V villosa is dominant is the only prevention.

A case of solanum malacoxylon toxicity in pigs.

The postmortem and histological changes seen in the kidneys, lungs and vascular system in spontaneous Solanum malacoxylon poisoning on a pig farm in Buenos Aires Province, Argentina, are reported. Macroscopic calcified plaques in the endocardium, aorta, and pulmonary artery and mineralization in renal pelvis were observed. Microscopic examinations revealed tubulonephrosis and calcification of the elastic fibers of kidney vessels. Severe calcinosis of the endocardium and elastic fibers of arteries (aorta, pulmonary, renal) were seen. In the lung, calcification of the elastic fibers of the alveolar wall and the lamina propia of the bronchia were also noted.

[Hyperestrogenism in swine due to natural poisoning with zearalenone]. / Hiperestrogenismo en cerdas por intoxicación natural con zearalenona.

A field case is described in which all prepuberal swine of a group of 20 pigs and 11 sows showed marked estrogenic effects. These consisted of enlarged mammary glands, swelled tumefacient vulva, and greatly enlarged internal reproductive organs. The corn used to feed these animals was found to contain 56 ppm zearalenone. Deoxynivalenol (4.9 ppm) was found in the corn; T-2 toxin, nivalenol, fusarenon-X, diacetoxyscirpenol, aflatoxins and ochratoxins were absent. Identity of Z was confirmed by TLC in four solvent systems, behavior of the suspected spots under UV light of different wavelengths, change of fluorescence from green to blue after spraying with 5% AlCl3 in alcohol and heating at 110 degrees C during 5 minutes, and by its UV spectrum. A zearalenone producing strain of Fusarium oxysporum was isolated from the suspected grain. Histopathology of uterine tissue showed typical changes produced by zearalenone: hyperplasia, hypertrophy, and metaplasia of the myometrium. Feeding of the grain to a prepuberal sow under controlled conditions reproduced all the effect found in the farm animals. This is the first field case of zearalenone poisoning reported in Argentina.

Hiperestrogenismo en cerdas por intoxicación natural con zearalenona / Hyperestrogenism in swine due to natural poisoning with zearalenone

Se describe un caso de intoxicación de cerdas prepúberes con zearalenona (Z) al consumir una dieta conteniendo 56 ppm Z. En el maíz contaminado se encontró una cepa de Fusarium oxysporum que produjo Z en cultivo sobre ese grano. Se indicaron la evidencias de distinta índole que permitieron confirmar que los efecto observados fueron producidos por dicha micotoxina

[Poisoning in cattle caused by blue-green algae]. / Intoxicacion en ganado bovino por algas verde-azuladas.

This paper describes a case of poisoning by blue-green algae growing in a fresh water pond in Goyena, Provincia de Buenos Aires. The predominating algae were identified as Microcystis aeruginosa. They show an intense growth when certain meteorologic condition prevail, in coincidence with certain chemical characteristics of the water. Once this growth has occurred, the direction of the wind has a decisive role, because it determines the accumulation on the shore, increasing their concentration and consequently, the risk of poisonous action. From a total of 170 cows, 72 died after ingestion of algae in a lapse of 24 hours. Death was very sudden so that symptoms could be observed in only 10 animals: diarrhea, incoordination, excitability, dyspnea and death. The gross lesions observed were: full stomachs showing the presence of algae; a serum-blood collection in the abdominal cavity and congestive intestines. Histopathology showed nephrosis and probable hepatic centrolobular necrosis. Water toxicity was tested on laboratory animals and gave positive results. The gross lesions, the histological changes and the laboratory tests, confirm the toxicity of the water in the pond. Toxin detection in the digestive content of the poisoned animals has not been previously mentioned in the literature; it is a very valuable diagnostic method.