Infectious sporadic bovine abortions: retrospective analysis.

Infectious sporadic abortions in cattle are mainly caused by opportunistic bacteria and fungi usually present in environmental or gastrointestinal and reproductive microbiota of healthy animals. A retrospective analysis was carried out to evaluate the main opportunistic microorganisms involved in bovine abortions recorded at INTA Balcarce (Argentina) from 1997 to 2023, accounting for 2.2% of the total diagnosed etiologies of bovine abortion. The opportunistic agents identified as the cause of abortion in 29 fetuses were bacteria (90%) and fungi (10%). Escherichia coli (n = 8), Trueperella pyogenes (n = 5), and Histophilus somni (n = 4) were the bacterial species most often identified as causing infectious abortions, whereas Aspergillus spp. (n = 3) was implicated in all fungal abortions identified. Pure culture of bacteria or fungus was achieved from abomasal content and/or lung essential. Main microscopic findings were bronchopneumonia, myo- and epicarditis, meningitis, and portal hepatitis. Herein, we highlight the importance of detecting potential infectious bacteria in cultures to improve etiological diagnosis of bovine abortions associated with compatible microscopic findings to confirm the etiology.

Identification of Sarcocystis spp. in synanthropic (Muridae) and wild (Cricetidae) rodents from Argentina.

The occurrence of Sarcocystis species was investigated in synanthropic (Muridae) and wild (Cricetidae) rodents from Argentina. Nine species were captured (n = 356). Sarcocysts were detected in muscles of 8.7% (31/356) and 3.7% (4/106) of the rodents by histopathology and direct microscopic observation, respectively. PCR-sequencing targeting the 18S rRNA, cox1, and ITS1 regions was performed on samples with positive histopathology. Four different 18S rRNA sequences or sequence groups with high intra-group identities (99.6-100%) were detected in Mus musculus, Oxymycterus rufus, Akodon azarae, and Necromys lasiurus. Eight sequences showed 99.5-99.7% identity with S. dispersa. Thirteen sequences showed low identity (95.3-96.4%) with other Sarcocystis spp. The obtained coxI sequences (n = 9) were almost identical to each other and showed a high similarity with S. strixi (99.2-99.5%) and S. lutrae (99.1%), despite the 18S rRNA sequences from the same samples suggested the occurrence of at least two species. This suggests that coxI may not show high variability in Sarcocystis spp. that use rodents as intermediate hosts. Six ITS1 sequences were obtained, showing high identity but low coverage with several Sarcocystis spp. Multilocus sequence typing and BLAST analysis did not lead to an accurate species identification. Possible reasons are the detection of new species or the limited molecular information available from previously described Sarcocystis spp. Phylogeny suggests that the detected Sarcocystis spp. may use raptor birds or snakes as definitive hosts. This study represents the first molecular identification of Sarcocystis spp. in naturally infected rodents of the Cricetidae and Muridae families in South America.

Transplacental infection by bovine alphaherpesvirus type 1 induces protein expression of COX-2, iNOS and inflammatory cytokines in fetal lungs and placentas.

Bovine alphaherpesvirus type 1 (BoAHV-1) is associated with respiratory and reproductive syndromes. Until present the immunologic mechanisms involved in BoAHV-1 abortion are partially known. We studied key elements of the innate immune response in the placentas and fetal lungs from cattle experimentally-inoculated with BoAHV-1. These tissues were analyzed by histopathology. Furthermore, virus identification was performed by qPCR and the expression of the inflammatory cytokines such as tumor necrosis factor-alpha, interleukin 1-alpha and inflammatory mediators like inducible nitric oxide synthase and cyclooxeganse-2 was evaluated by immunohistochemistry. The viral transplacental infection was confirmed by the detection of BoAHV-1 by qPCR in the placenta and fetal organs, which revealed mild inflammatory lesions. Inducible nitric oxide synthase immunolabelling was high in the lungs of infected fetuses and placentas, as well as for tumor necrosis factor-alpha in the pulmonary parenchyma and cyclooxeganse-2 in fetal annexes. However, the expression of interleukin 1-alpha was weak in these organs. To our knowledge, this is the first study that provides strong evidence of an early immune response to BoAHV-1 infection in the conceptus. Advances in the knowledge of the complex immunological interactions at the feto-maternal unit during BoAHV-1 infection are needed to clarify the pathogenesis of abortion.

A review of cardiac blackleg in cattle, and report of 2 cases without skeletal muscle involvement in Argentina.

Blackleg is an infectious disease caused by Clostridium chauvoei. Cardiac blackleg has been reported in ruminants as an uncommon presentation of the disease; its pathogenesis is not understood completely. We include here a literature review of cardiac blackleg and a description of 2 cases in 12-15-mo-old feedlot steers in Argentina. Fourteen of 1,190 steers died suddenly over a period of 10 d. Postmortem examinations were performed on 5 of these animals. Grossly, severe, diffuse, fibrinous pericarditis and pleuritis, multifocal necrohemorrhagic myocarditis, diffuse pulmonary congestion, mild splenomegaly, and moderate congestion of meningeal vessels were observed. No significant gross lesions were observed in the skeletal muscles of any animal. Histology was performed on 2 of the steers. The main microscopic features were necrotizing myocarditis with myriad intralesional gram-positive rods with subterminal spores plus fibrinosuppurative pericarditis and pleuritis. C. chauvoei was detected by immunohistochemistry and PCR in the myocardium of both animals. These findings confirm a diagnosis of cardiac blackleg in these 2 steers and presumptively in the other affected animals.

Spatial-temporal trends and economic losses associated with bovine abortifacients in central Argentina.

The aims of this work are, firstly, to provide the geolocalization of cases of bovine abortion with definitive diagnosis and, secondly, to estimate the economic losses due to the most frequent abortifacients diagnosed agents in cattle in Buenos Aires province, Argentina. The total beef and dairy cattle population at risk of abortion is 8,358,186 and 538,076, respectively. In beef cattle, the overall risk of abortion was estimated at 4.5% for all pregnancies, where 27.9% are due to Campylobacter fetus, Neospora caninum, Leptospira spp., Brucella abortus, and bovine viral diarrhea virus with economic losses of US$ 440 per abortion, being the annual loss to the beef industry of US$ 50,144,101. In dairy cattle, there was an 8.0% risk of suffering abortion, 26.1% produced by the same abortigenic agents. The economic losses were estimated at US$ 1,415 per abortion, which equals a total loss of US$ 17,298,498 for the dairy industry in the region. The results of this study show that infectious causes are highly prevalent in Buenos Aires province, and they caused severe economic impacts in the dairy and beef industries. Furthermore, changes in temporal trends of infectious abortion occurrence were detected, probably related to the inclusion of molecular diagnostic techniques with more sensitivity or different epidemiological or husbandry conditions in the region analyzed.

Morphometric study of encephalic lesions in aborted bovine fetuses naturally infected by two subpopulations of Neospora caninum.

Neospora caninum is a major reproductive disease in cattle worldwide. In the Argentinian Humid Pampa, the seroprevalence, incidence of abortions, and economic losses due to neosporosis are considerably higher in dairy than in beef cattle. Despite this, we recently demonstrated that N. caninum subpopulations are indistinctly distributed in both dairy and beef production systems. The association between genotypic characteristics defined by microsatellite analysis and the virulence of the different strains-particularly with regard to the severity and extension of histological lesions-is largely unknown. Herein, we used a morphometric approach to analyze encephalic lesions in 62 bovine fetuses spontaneously infected by N. caninum. Morphometric parameters (average size of focal lesions, number of foci/cm2 and the percentage of the section affected by lesions) were compared according to the N. caninum subpopulations found in our previous microsatellite genotyping analysis, animal biotype (beef versus dairy), and fetal age (second stage of gestation versus third stage). The average size of the lesions differed significantly among fetuses with different gestational ages; however, no significant differences among animal biotypes or genotypic patterns were found. Further research into the genetic, molecular, and husbandry factors that could account for this greater impact in Argentinian dairy herds is needed.

Retrospective analysis of hairy vetch (Vicia villosa roth) poisoning in Argentina (2004-2019).

Hairy vetch (Vicia villosa) poisoning in cattle is characterized by a systemic granulomatous inflammatory response that resembles a type-IV hypersensitivity reaction. Hairy vetch toxicity has been described in cattle worldwide. The aim of this paper was to describe 10 outbreaks of hairy vetch poisoning in cattle studied at INTA EEA Salta and INTA EEA Balcarce, Argentina, from 2004 to 2019. Clinical signs included weakness, pyrexia, dermatitis, alopecia, and progressive weight loss, which leads to death over a clinical course of approximately two weeks. A total of 12 necropsies were performed and tissue samples were collected for histopathology. The main gross changes were observed in skin, lymph nodes, liver, heart, spleen and kidneys. Other tissues, such as pancreas, thyroid, and adrenal glands, were also affected. Histological lesions consisted of multifocal to diffuse granulomatous inflammation in those organs. The toxicity of hairy vetch has been described in several countries of the world. In Argentina, the use of hairy vetch as a cover crop has become common in some regions during the past years. The data suggest that hairy vetch poisoning is an important disease in cattle. More studies are needed to contribute with further information.

Neospora caninum and Toxoplasma gondii as causes of reproductive losses in commercial sheep flocks from Argentina.

The aim of this study is to provide preliminary data about the occurrence of Neospora caninum- and Toxoplasma gondii-related abortions and perinatal deaths in sheep from Argentina. Thirty ovine aborted foetuses and 33 perinatal deaths were submitted to the Veterinary Diagnostic Service at INTA EEA Balcarce (Argentina) during 2017-2019. A complete necropsy was performed on all specimens submitted, and foetal and placental tissues were examined. Foetal cavity fluids were collected for assessment of antibodies to N. caninum and T. gondii by indirect fluorescent antibody technique (IFAT). Placental and foetal tissue samples were collected for DNA extraction and histopathological analysis. The differential diagnosis with other causes of abortion was carried out. Of the sampled specimens, 20.63% (13/63) displayed evidence for N. caninum infection by IFAT and PCR, and in 61.5% (8/13) of the positive specimens the parasite was confirmed as the cause of abortion/perinatal death based on the presence of compatible histological lesions and/or positive immunohistochemistry test, positive PCR and/or positive IFAT, and no other infectious agents diagnosed. In contrast, T. gondii infection was confirmed in 9.52% (6/63) of the analysed specimens, but only in 2 lambs T. gondii was determined as the death cause. Neospora caninum and T. gondii co-infections were confirmed in 4 analysed specimens (2 aborted foetuses and 2 perinatal deaths). These results demonstrated that N. caninum is efficiently transmitted and a frequent cause of ovine reproductive failure in the commercial analysed flocks compared with T. gondii. Despite T. gondii congenital infection was detected in some specimens (6/63), it was confirmed as the cause of death in only two of them. Thus, and considering the limited availability of confirmed samples, we could not determine whether toxoplasmosis is a major problem in Argentinian sheep flocks or not. More studies on a greater number of specimens from different ovine production systems under different management conditions are necessary to assess the real impact of neosporosis and toxoplasmosis in Argentina.

Microsatellite genotyping reveals extensive genetic diversity in bovine Neospora caninum from the humid Pampa region in Argentina.

Neospora caninum is an apicomplexan protozoan and a major cause of abortion in cattle worldwide. In the Argentinian Humid Pampa, bovine neosporosis causes severe economic losses. Despite this, information on the genetic structure of N. caninum in this region is limited. Therefore, this study aimed to genetically characterize N. caninum isolates associated with bovine abortion in the Humid Pampa region. For this purpose, spontaneous bovine fetal tissues submitted for diagnosis to the Veterinary Diagnostic Service at INTA Balcarce during 2008-2019 were assessed by PCR, indirect fluorescent antibody test (IFAT), and histologic analysis. PCR-positive samples were tested by multilocus microsatellite genotyping (MLGs) using 9 microsatellite markers. Thirty-one different genotypes were identified from 32 samples with at least seven markers. Argentinian MLGs were grouped into two clonal clusters when analyzed using eBURST network and principal coordinate analysis. No segregation based on the year of collection, animal biotype, or geographic origin was observed. In addition, the presence of linkage disequilibrium supported the clonal propagation of Argentinian MLGs. One Argentinian subpopulation was associated with isolates from Spain, Uruguay, Brazil, and Mexico, and the other one was linked to isolates from Scotland, Spain, and Germany. These findings reveal the presence of two clonal subpopulations of N. caninum in the Humid Pampa.

Detection methods and characterization of bovine viral diarrhea virus in aborted fetuses and neonatal calves over a 22-year period.

Detection of bovine viral diarrhea virus (BVDV) in aborted fetus samples is often difficult due to tissue autolysis and inappropriate sampling. Studies assessing different methods for BVDV identification in fetal specimens are scarce. The present study evaluated the agreement between different diagnostic techniques to detect BVDV infections in specimens from a large number of bovine aborted fetuses and neonatal deaths over a period of 22 years. Additionally, genetic, serological, and pathological analyses were conducted in order to characterize BVDV strains of fetal origin. Samples from 95 selected cases from 1997 to 2018 were analyzed by antigen-capture ELISA (AgELISA), nested RT-PCR (RT-nPCR), and real-time RT-PCR (RT-qPCR). In addition, amplification and sequencing of the 5'UTR region were performed for phylogenetic purposes. Virus neutralization tests against the BVDV-1a, BVDV-1b, and BVDV-2b subtypes were conducted on 60 fetal fluids of the selected cases. Furthermore, the frequency and severity of histopathological lesions were evaluated in BVDV-positive cases. This study demonstrated that RT-nPCR and RT-qPCR were more suitable than AgELISA for BVDV detection in fetal specimens. However, the agreement between the two RT-PCR methods was moderate. The BVDV-1b subtype was more frequently detected than the BVDV-1a and BVDV-2b subtypes. Neutralizing antibodies to any of the three subtypes evaluated were present in 94% of the fetal fluids. Microscopically, half of the BVDV-positive cases showed a mild non-suppurative inflammatory response. These results emphasize the need to consider different methods for a diagnostic approach of BVDV associated to reproductive losses.

Ovine Abortion by Neospora caninum: First Case Reported in Argentina.

PURPOSE: The aim of this study was to describe for the first time a natural case of ovine abortion associated with Neospora caninum in a flock with reproductive losses in Argentina. MATERIALS AND METHODS: The analyzed flock consisted of 256 Texel sheep, of which 134 had been mated. A single blood sample was obtained by jugular vein puncture from 220 ewes (116 adult ewes, 104 yearling ewes) and 93 lambs. Serum samples and fetal fluid were tested using the indirect fluorescence antibody test to detect antibodies against N. caninum and T. gondii. Fetal and placental tissues from aborted fetus were examined by standard gross pathology procedures and were tested using histopathology and immunohistochemistry. Moreover, DNA from fetal and placental tissues was isolated and a PCR assay to detect N. caninum, T. gondii and Chlamydia spp. was used. RESULTS AND DISCUSSION: The pregnancy rate was 89% (119/134), the abortion rate was 8.4% (10/119) whereas the perinatal mortality rate was 15% (16/109). Out of 116 adult ewes sampled, 34.48% presented anti-N. caninum antibodies. Ten ewes had aborted, and one fetus was directly submitted to the diagnostic laboratory for further processing. Antibodies against N. caninum were detected in fetal fluid and in the aborted dam. Histopathological analysis in fetal tissues showed multifocal lymphohistiocytic glossitis, diffuse mild lymphohistiocytic endocarditis, pericarditis and focally extensive myocarditis. Severe multifocal necrotizing placentitis and diffuse mild lymphohistiocytic placentitis with the presence of lymphohistiocytic vasculitis were observed in placenta. N. caninum was immunolabeled in the placenta and fetal tongue. In addition, N. caninum DNA was detected in placenta, central neural system, lung and heart of the aborted fetus. There was no evidence of other infectious abortifacients in the aborted fetus. CONCLUSION: The present study described for the first time an ovine abortion caused by N. caninum in Argentina. Further investigations at a larger scale are required to establish the role of N. caninum as an important cause of reproductive losses in sheep flocks from the region.

Intramural Vascular Edema in the Brain of Goats With Clostridium perfringens Type D Enterotoxemia.

Enterotoxemia caused by Clostridium perfringens type D is an important disease of sheep and goats with a worldwide distribution. Cerebral microangiopathy is considered pathognomonic for ovine enterotoxemia and is seen in most cases of the disorder in sheep. However, these lesions are poorly described in goats. In this article, we describe the vasculocentric brain lesions in 44 cases of caprine spontaneous C. perfringens type D enterotoxemia. Only 1 goat had gross changes in the brain, which consisted of mild cerebellar coning. However, 8 of 44 (18%) cases showed microscopic brain lesions, characterized by intramural vascular proteinaceous edema, a novel and diagnostically significant finding. The precise location of the edema was better observed with periodic acid-Schiff, Gomori's, and albumin stains. Glial fibrillary acidic protein and aquaporin 4 immunostaining revealed strong immunolabeling of astrocyte foot processes surrounding microvessels. The areas of the brain most frequently affected were the cerebral cortex, corpus striatum (basal ganglia), and cerebellar peduncles, and both arterioles and venules were involved. Most of the goats of this study showed lesions in the intestine (enteritis, colitis, and typhlitis), although pulmonary congestion and edema, hydrothorax, hydropericardium, and ascites were also described. Although the intramural edema described, for the first time, in these caprine cases is useful for the diagnosis of enterotoxemia when observed, its absence cannot exclude the disease.

Current trends in bovine abortion in Argentina / Tendências atuais do aborto bovino na Argentina

Bovine abortion is an important cause of significant economic losses in beef and dairy herds. This syndrome is usually difficult to diagnose. The aim of this study was to characterize bovine abortion causes in Argentina by standard diagnosis procedures (histology, bacterial and viral isolation) and other diagnostic tests like direct fluorescent antibody test (DFAT), fetal serology, immunohistochemistry (IHC), and PCR, showing their specific advantages and limitations. Necropsies were performed in 150 aborted bovine fetuses submitted to the diagnostic laboratories of Instituto Nacional de Tecnología Agropecuaria (INTA) Balcarce, Argentina. Etiological diagnosis was confirmed in 78 fetuses (52% of the cases). Most causes of abortion were of infectious origin, being Neospora caninum (14.67%), Campylobacter fetus sp. (9.33%), Leptospira spp. (7.33%) and Brucella abortus (6.65%) the main microorganisms identified. Bovine viral diarrhea virus (BVDV) and bovine herpes virus (BHV) were diagnosed in 2 (1.33%) and 3 (2%) cases, respectively. This study showed a better characterization of bovine abortion compared with previous researches done on this topic.(AU)

O aborto bovino é uma causa importante de perdas econômicas significativas em rebanhos bovinos e leiteiros. Esta síndrome é geralmente difícil de diagnosticar. O objetivo deste estudo foi caracterizar o aborto bovino na Argentina por procedimentos diagnósticos de rotina (histologia, isolamento viral e bacteriana) e outros testes diagnósticos como ensaio directo de anticorpos fluorescentes (DFAT), sorologia fetal, imuno-histoquica (IHC), e PCR; mostrando suas vantagens e limitações específicas. As necropsias foram realizadas em 150 fetos bovinos abortados submetidos aos laboratórios de diagnóstico do Instituto Nacional de Tecnologia Agropecuária (INTA) de Balcarce, na Argentina. O diagnóstico etiológico foi confirmado em 78 fetos (52% dos casos). A maioria das causas de aborto foram de origem infecciosa, sendo Neospora caninum (14,67%), Campylobacter fetus sp. (9,33%), Leptospira spp. (7,33%) e Brucella abortus (6,65%) os principais microrganismos identificados. O vírus da diarréia viral bovina (BVDV) e o herpesvírus bovino (BHV) foram diagnosticados em 2 (1,33%) e 3 (2%) casos, respectivamente. Este estudo mostrou uma melhor caracterização do aborto bovino em comparação com pesquisas anteriores feita sobre este tema.(AU)

Enteric listeriosis in grazing steers supplemented with spoiled silage.

An outbreak of enteric listeriosis in steers that were fed spoiled silage is reported. The outbreak started 2 days after ~200 animals in a single paddock were given a supplement of spoiled silage. Forty animals (20%) were affected, and 13 (6.5%) died over a period of 10 days. Affected animals were recumbent, depressed, and had diarrhea with mucus and fibrin. Gross and microscopic findings in 3 animals that were subjected to autopsy included excess peritoneal fluid, congestion and edema of abomasum, suppurative enteritis and colitis, and suppurative mesenteric lymphadenitis. Two strains of Listeria monocytogenes were isolated, one of serotype 1/2c from the gallbladder and one of serotype 1/2b from the spoiled silage. Listeria monocytogenes was detected in the mesenteric lymph nodes and intestinal wall of 1 animal by immunohistochemistry (IHC). Clinical history and signs, gross and microscopic findings, bacterial isolation, and IHC results confirmed a diagnosis of enteric listeriosis. The source of infection was likely the spoiled silage.

A Neospora caninum vaccine using recombinant proteins fails to prevent foetal infection in pregnant cattle after experimental intravenous challenge.

The aim of the present study was to evaluate the immunogenicity and protective efficacy of rNcSAG1, rNcHSP20 and rNcGRA7 recombinant proteins formulated with immune stimulating complexes (ISCOMs) in pregnant heifers against vertical transmission of Neospora caninum. Twelve pregnant heifers were divided into 3 groups of 4 heifers each, receiving different formulations before mating. Immunogens were administered twice subcutaneously: group A animals were inoculated with three recombinant proteins (rNcSAG1, rNcHSP20, rNcGRA7) formulated with ISCOMs; group B animals received ISCOM-MATRIX (without antigen) and group C received sterile phosphate-buffered saline (PBS) only. The recombinant proteins were expressed in Escherichia coli and purified nickel resin. All groups were intravenously challenged with the NC-1 strain of N. caninum at Day 70 of gestation and dams slaughtered at week 17 of the experiment. Heifers from group A developed specific antibodies against rNcSAG1, rNcHSP20 and rNcGRA7 prior to the challenge. Following immunization, an statistically significant increase of antibodies against rNcSAG1 and rNcHSP20 in all animals of group A was detected compared to animals in groups B and C at weeks 5, 13 and 16 (P<0.001). Levels of antibodies against rNcGRA7 were statistical higher in group A animals when compared with groups B and C at weeks 5 and 16 (P>0.001). There were no differences in IFN-γ production among the experimental groups at any time point (P>0.05). Transplacental transmission was determined in all foetuses of groups A, B and C by Western blot, immunohistochemistry and nested PCR. This work showed that rNcSAG1, rNcHSP20 and rNcGRA7 proteins while immunogenic in cattle failed to prevent the foetal infection in pregnant cattle challenged at Day 70 of gestation.

[Endemic and epidemic bovine neosporosis: description of two events in beef cattle]. / Neosporosis epidémica y endémica: descripción de dos eventos en bovinos para cría.

The aim of this study was to describe two events in which Neospora caninum was involved in bovine abortions in beef cattle. In the first event, 11 abortions in 57 heifers were recorded in 45 days. One aborted heifer was 5 times more likely to be seropositive than a non-aborted heifer (OR=4.9; IC 1.2-19.9) (p<0.05). In the second event, no association between serological results and abortions were observed (OR=0,69; 0,06-7,31) (p>0.05). Neither antibodies nor isolation of other pathogens were achieved in any case. On the contrary, antibodies and pathognomonic histopathological lesions were observed in the four fetuses from both cases. Interestingly, the findings in the first event suggest the epidemic behavior of the disease. In contrast, in the second event it appears that few abortions were due to N. caninum, suggesting the presence of endemic neosporosis.

Neosporosis epidémica y endémica: descripción de dos eventos en bovinos para cría. / [Endemic and epidemic bovine neosporosis: description of two events in beef cattle].

The aim of this study was to describe two events in which Neospora caninum was involved in bovine abortions in beef cattle. In the first event, 11 abortions in 57 heifers were recorded in 45 days. One aborted heifer was 5 times more likely to be seropositive than a non-aborted heifer (OR=4.9; IC 1.2-19.9) (p<0.05). In the second event, no association between serological results and abortions were observed (OR=0,69; 0,06-7,31) (p>0.05). Neither antibodies nor isolation of other pathogens were achieved in any case. On the contrary, antibodies and pathognomonic histopathological lesions were observed in the four fetuses from both cases. Interestingly, the findings in the first event suggest the epidemic behavior of the disease. In contrast, in the second event it appears that few abortions were due to N. caninum, suggesting the presence of endemic neosporosis.

Concomitant infection of Neospora caninum and Bovine Herpesvirus type 5 in spontaneous bovine abortions / Infecção simultânea de Neospora caninum e Herpesvirus bovino tipo 5 em casos espontâneos de aborto bovino

Bovine Herpesvirus type 5 (BoHV-5) has not been conclusively demonstrated to cause bovine abortion. Brain lesions produced by Neospora caninum and Bovine Herpesvirus type 1 (BoHV-1) exhibit common features. Therefore, careful microscopic evaluation and additional diagnostic procedures are required to achieve an accurate final etiological diagnosis. The aim of the present work was to investigate the occurrence of infections due to BoHV-1, BoHV-5 and N. caninum in 68 cases of spontaneous bovine abortions which showed microscopic lesions in the fetal central nervous system. This study allowed the identification of 4 (5.9%) fetuses with dual infection by BoHV-5 and N. caninum and 33 (48.5%) cases in which N. caninum was the sole pathogen identified. All cases were negative to BoHV-1. The results of this study provide evidence that dual infection by BoHV-5 and N. caninum occur during pregnancy in cattle; however, the role of BoHV-5 as a primary cause of bovine abortion needs further research. Molecular diagnosis of BoHV-5 and N. caninum confirmed the importance of applying complementary assays to improve the sensitivity of diagnosing bovine abortion.

Não está demonstrado até ao momento, que o Herpesvírus bovino tipo 5 (BoHV-5) seja um agente causal de aborto bovino. Uma vez que as lesões cerebrais tanto de Neospora caninum como de Herpesvírus bovino tipo 1(BoHV-1) têm características similares, é necessária uma avaliação microscópica cuidadosa, bem como exames laboratoriais adicionais, para obter um diagnóstico final preciso. O objetivo do presente trabalho foi investigar a presença de infeções por BoHV-1, BoHV-5 e N. caninum em 68 casos de aborto espontâneo, nos quais se verificaram lesões microscópicas no sistema nervoso central. Foram encontrados 4 (5,9%) fetos com infeção simultânea de BoHV-5 e N. caninum e 33 (48,5%) casos com infeção exclusiva de N. caninum. Todos os casos foram negativos a BoHV-1. Os resultados deste estudo demonstram que a infeção dual por BoHV-5 y N. caninum está presente durante a gestçao dos bovinos. Apesar disso, o papel de BoHV-5 como agente primário causal de aborto, carece de mais investigaçao. O diagnóstico molecular de BoHV-5 e N. caninum confirmou a importância de se aplicar ensaios complementares para melhorar a sensibilidade do diagnóstico de aborto bovino.