Resumen: Los problemas reproductivos y sanitarios representan una de las limitantes de mayor impacto productivo en los rodeos lecheros del Uruguay. Las alteraciones en los índices reproductivos pueden deberse a una amplia diversidad de causas, las cuales exigen un correcto diagnóstico. Actualmente los antecedentes de encuestas en el rubro lechero son proporcionados por la Oficina de Estadísticas Agropecuarias y el Instituto Nacional de Leche. El objetivo de este estudio fue caracterizar las prácticas de manejo, reproductivas y sanitarias en los establecimientos lecheros del Uruguay. Se diseñó un estudio transversal de los establecimientos lecheros del Uruguay. Se creó una encuesta la cual fue realizada en el año 2015. Fueron seleccionados 107 predios lecheros de acuerdo al tamaño de población bovina a partir de un muestreo aleatorio estratificado. Las preguntas se enfocaron en características generales del predio, estrategias y características sanitarias, y estrategias y características reproductivas. La tasa de respuesta fue del 95,3 %. De los predios encuestados, el 95,6 ±1,8 % tenía asesoramiento veterinario. La técnica de inseminación artificial se utilizó en el 83,8 ±5,2 %. Un 59,9 ± 5,5 % de los predios realizaban diagnóstico de gestación. La tasa de preñez estimada fue del 79,5 ±1,5 %. La evaluación de los toros previo al servicio se realizó en el 49,0 ±7,6 % de los tambos. La principal causa de refugo fue por dentición. La utilización de vacunas como medida preventiva para enfermedades reproductivas se utilizó en el 56,6 ±5,4 % de los productores lecheros. El 58,7 ±6,7 % de los encuestados declaró no tener ningún antecedente de enfermedades reproductivas. La media de abortos vistos anualmente fue de 4,4 ±0,6. Las tasas de preñez no pudo asociarse a aspectos reproductivos y/o sanitarios. Se pudo determinar que el aspecto demográfico cumple un rol significativo en la elección de los aspectos reproductivos y de manejo en los establecimientos lecheros del Uruguay.

Summary: Ones of the most important limitations on dairy herd of Uruguay are the reproductive and health problems. Alterations on reproductive rates may be due to a wide variety of causes, which require a correct diagnosis. Currently in Uruguay, histories of surveys in dairy sector were provided by the “Oficina de Estadísticas Agropecuarias” and the “Instituto Nacional de Leche”. The aim of this study was to characterize the management, reproductive and health practices in dairy farms in Uruguay. A cross-sectional study was carried out in 2015. Dairy herds were stratified by size and 107 herds were randomly selected throughout all the Uruguayan territory. A survey was made on these herds; the questions were focused on general characteristics of the farms, strategies and health characteristics, and strategies and reproductive characteristics. The response rate of the survey was 95.3%. Of the surveyed farms, 95.6 ± 1.8% had veterinary service. The artificial insemination technique was used in 83.8 ± 5.2%. Fifty-nine percent of the farms made a pregnancy diagnosis. The estimated pregnancy rate was 79.5 ± 1.5%. The pre-service evaluation of the bulls was carried out in 49.0 ± 7.6% of the dairy farms. The main cause of culling was due to teething. Use of vaccines as a preventive measure for reproductive diseases was 56.6 ± 5.4% of the dairy farms. Fifty-eight percent of those surveyed had no history of reproductive diseases. The mean of abortions seen annually was 4.4 ± 0.6. Pregnancy rates could not be associated with reproductive and/or health aspects. It was possible to determine that the demographic aspect is a key role in the choice of reproductive and management aspects in dairy farms in Uruguay.

RESUMO: Uma série de casos foi estudada para determinar a frequência de causas do aborto em bovinos leiteiros no Uruguai. A amostra, de 102 casos, foi composta por 53 fetos, 35 fetos com placentas e 14 placentas sem feto associado. Todos os casos foram submetidos a exames patológicos macroscópicos e microscópicos, além de testes microbiológicos e sorológicos. A etiologia foi determinada em 54 (53%) dos casos, 51 dos quais foram causados por agentes infecciosos. Nos 102 casos observados, 30 (29%) foram causados por Neospora caninum, seis (6%) por Coxiella burnetii e dois (2%) por Campylobacter fetus subsp. venerealis. O vírus da Parainfluenza-3 e Salmonella enterica serovar Newport causaram um aborto cada. Bactérias oportunistas (Escherichia coli, Streptococcus sp., Staphylococcus sp., Mannheimia sp., Trueperella pyogenes e Providencia stuartii) foram associadas a 11 abortos. Em dois casos, a morte fetal foi atribuída a distocia e, em um caso, o feto apresentava mesotelioma congênito. A infecção pelo vírus da diarreia viral bovina (BVDV) foi identificada em três fetos; dois dos quais foram co-infectados e apresentavam lesões típicas de N. caninum. Não foram observadas lesões no outro feto infectado pelo BVDV. Leptospira interrogans foi identificada em um feto sem lesões. Apesar da relativamente baixa taxa de sucesso no diagnóstico etiológico nos casos de aborto em bovinos, é necessário o diagnóstico sistemático dos abortos para estabelecer estratégias de prevenção e controle. Isso também facilita o monitoramento e a vigilância de doenças reprodutivas em bovinos leiteiros, algumas das quais representam um risco para a saúde pública.

ABSTRACT: A case series study was conducted to determine the frequency of causes of abortion in dairy cattle in Uruguay. The sample size of 102 cases was composed of 53 fetuses, 35 fetuses with placentas, and 14 placentas without an associated fetus. All cases underwent gross and microscopic pathologic examinations as well as microbiological and serological testing. The etiology was determined in 54 (53%) of cases, 51 of which were caused by infectious agents. Within the observed 102 cases, 30 (29%) were caused by Neospora caninum, six (6%) by Coxiella burnetii and two (2%) by Campylobacter fetus subsp. venerealis. Bovine Parainfluenza-3 virus and Salmonella enterica serovar Newport caused one abortion each. Opportunistic bacteria (Escherichia coli, Streptococcus sp., Staphylococcus sp., Mannheimia sp., Trueperella pyogenes, and Providencia stuartii) were associated with 11 abortions. In two cases the fetal death was attributed to dystocia, and in one case the fetus had a congenital mesothelioma. Bovine viral diarrhea virus (BVDV) infection was identified in three fetuses; two of which were co-infected with and had typical lesions of N. caninum. No lesions were observed in the other fetus infected by BVDV. Leptospira interrogans was identified in one fetus without lesions. Despite the relatively low overall success rate in establishing an etiological diagnosis in cases of abortion in cattle, a systemic workup of bovine abortion is necessary to establish prevention and control strategies. This also facilitates monitoring and surveillance of reproductive diseases in dairy cattle, some of which represent a risk to public health.

Abstract In November 2015, an abortion outbreak occurred in a commercial dairy herd of 650 Holstein cows in Florida department, Uruguay. Forty-five (45) cows aborted within 3 wk. Five fetuses were subjected to gross and microscopic pathologic examination, and microbiological testing. One fetus had fibrinous epicarditis and peritonitis, and neutrophilic bronchopneumonia. Campylobacter fetus subsp. venerealis was detected by direct immunofluorescence, isolated and identified by PCR and sequencing of the 16S rDNA in the abomasal fluid and/or lung. Histologic examination of two other fetuses revealed non-suppurative necrotizing encephalitis, lymphohistiocytic myositis and myocarditis, and lymphocytic interstitial nephritis. In these fetuses, N. caninum antigen was detected intralesionally by immunohistochemistry, and N. caninum DNA was amplified by PCR on formalin-fixed paraffin-embedded brain. Antibodies against N. caninum were detected by indirect immunofluorescence in 10 of 27 cows, with titers ranging from 1/200 to 1/3200. The results indicate that two abortigenic microorganisms may coexist and cause contemporaneous abortion in a herd. It is relevant to highlight the importance of performing multiple diagnostic tests in various aborted dams and fetuses from the same herd for the etiologic confirmation of bovine abortion syndrome.

Resumen En noviembre de 2015 ocurrió un brote de abortos en un hato lechero comercial de 650 vacas Holstein en el departamento de Florida, Uruguay. Cuarenta y cinco (45) vacas abortaron en un lapso de 3 semanas. Cinco fetos fueron sometidos a un examen patológico macro y microscópico y a pruebas microbiológicas. Un feto tenía epicarditis fibrinosa y peritonitis, así como bronconeumonía neutrofílica. Se detectó Campylobacter fetus subesp. venerealis utilizando inmunofluorescencia directa; se lo aisló e identificó mediante PCR y secuenciación del 16S rDNA en el líquido abomasal y en el pulmón. El examen histológico de otros dos fetos reveló encefalitis necrotizante no supurativa, miositis linfohistiocítica y miocarditis, y nefritis linfocítica intersticial. En estos fetos se detectó intralesionalmente el antígeno de N. caninum mediante análisis inmunohistoquímico, y se amplificó el ADN de N. caninum mediante PCR en tejido cerebral fijado con formalina y embebido en parafina. Se detectaron anticuerpos contra N. caninum mediante inmunofluorescencia indirecta en 10 de 27 vacas, con títulos de entre 1/200 y 1/3200. Los resultados indican que dos microorganismos abortígenos pueden coexistir y provocar abortos contemporáneos en un hato. Subrayamos la importancia de realizar pruebas diagnósticas múltiples en diversas madres abortadas y fetos del mismo hato para obtener una confirmación etiológica del síndrome de aborto bovino.