Síndrome do mau ajustamento neonatal em potros: foco em neuroesteróides / Foal mal adjustment syndrome: focus on neurosteroids

O processo de transição do feto para a vida extra-uterina é considerado um período crítico que requer complexas adaptações fisiológicas do potro neonato. Eventos estressores de origem hipóxicoisquêmicas no periparto podem desencadear um quadro de encefalopatia neonatal equina, também conhecida como síndrome do mau ajustamento neonatal. O diagnóstico é feito baseado na avaliação clínica e na anamnese e avaliação do histórico da gestação. Casos leves a moderados tem prognóstico favorável. É imprescindível o entendimento da endocrinologia da gestação, do papel dos neuroesteróides no desenvolvimento do sistema nervoso fetal para que o estabelecimento precoce da terapia adequada seja realizado de maneira bem sucedida. Assim, o objetivo do presente é abordar os principais aspectos clínicos e fisiopatológicos da Síndrome do Mau Ajustamento Neonatal em neonatos equinos, com foco especial no papel dos neuroesteróides durante a maturação cerebral do feto no terço final da gestação e na transição para a vida extra-uterina.

The transition from fetus to extrauterine life is considered a critical period that requires complex physiological adaptations on the part of the newborn foal. Peripartum hypoxic-ischemic stressors can result in equine neonatal encephalopathy, also known to as neonatal maladjustment syndrome. The diagnosis is made based on clinical examination, anamnesis, and a review of the mare’s pregnancy history. Cases that are mild to moderate in severity have a favorable prognosis. It is critical to understand the endocrinology of pregnancy and the role of neurosteroids in the development of the fetal nervous system in order to successfully initiate appropriate therapy early. Thus, the purpose of this article is to discuss the major clinical and pathophysiological aspects of neonatal maladjustment syndrome in equine neonates, with a particular emphasis on the role of neurosteroids during fetal brain maturation in the final third of pregnancy and during the transition to extrauterine life.

Monitoramento do parto em éguas / Monitoring the parturition in mares

O objetivo do presente é explorar aspectos da fisiologia do final da gestação em éguas, com foco na maturação do feto e monitoramento do parto nessa espécie. Inúmeras são as particularidades na endocrinologia da gestação, que culminam em uma ampla variação no tempo de gestação na égua e uma tardia maturação orgânica no potro, que se completa somente após o nascimento. A primeira fase do parto é considerada prodrômica, marcada pela inquietação e desconforto na égua, e movimentação do potro para apresentação longitudinal anterior, posição dorso-sacra e atitude estendida. A segunda fase do parto é o momento crítico e rápido que inicia com a ruptura do corioalantóide e não deve ultrapassar 30 minutos, desde a ruptura da placenta até a expulsão completa do potro neonato. A terceira fase é caracterizada pela expulsão da placenta, a qual deve ser avaliada pelo obstetra. O monitoramento do potro neonato é marcado pela observação dos reflexos posturais e comportamentais, além do exame físico e exames complementares. O momento do parto é decisivo na vida do potro neonato, sendo necessária a compreensão que o monitoramento dessa etapa é uma estratégia de ação que só alcança sucesso quando realizado de forma continuada ao acompanhamento obstétrico sistemático.

The purpose of this article is to examine the physiological characteristics of the final third of pregnancy in mares, with a particular emphasis on fetal maturation and parturition monitoring. There are numerous peculiarities in the endocrinology of equine pregnancy, culminating in a wide variation in the length of gestation in the mare and a delayed systemic maturation in the foal, which is completed only after birth. The first stage of labor, also known as prodromal stage, is characterized by restlessness and discomfort of the mare, as well as the foal's transition to anterior longitudinal presentation, dorso-sacral position, and extended attitude. The second stage labor is a critical and rapid period that begins with the chorioallantois rupture and should last no more than 30 minutes, from the rupture of the placenta to the complete expulsion of the neonatal foal. The third stage is characterized by the elimination of the placenta, which must be evaluated by the veterinarian. The assessment of the neonatal foal is performed by the observation of righting reflexes, in addition to physical examination and complementary exams. The parturition is a decisive moment in the life of the foal, and it is necessary to understand that monitoring this stage is an action strategy that only achieves success when carried out continuously with systematic obstetric follow-up.

Occurrence of Gasterophilus spp. in weanling foals in southern Brazil

The occurrence of gastrointestinal myiasis caused by Gasterophilus spp. larvae (Diptera: Oestridae) in adult horses has been widely characterized, however data on natural infestation in young foals have been lacking. This observation may be related to the absence of conclusive diagnosis in these individuals, most likely due to logistical or financial constraints. Gastric ulceration is a problem and a significant cause of morbidity in foals, particularly during the weaning stage; therefore, gasterophilosis should be included in the differential diagnosis. The primary purpose of this study was to determine the prevalence of gasterophilosis in 4- to 6-month-old weanling foals. Seventy-one healthy weanling foals were enrolled in the study. Physical assessment blood sampling and was completed in all foals before the commencement of the experiment. Gastroscopy examinations were performed under sedation (Detomidine 0.01 - 0.02 mg/kg) with a flexible endoscope inserted through nasogastric via. The lumen of the stomach was examined in order to search for botflies' larvae. Following gastroscopy, foals were classified into 2 groups based on the presence of Gasterophilus spp. larvae in their stomachs: 1) Infected and 2) Not Infected. Infected foals received a single dose of commercial trichlorfon and albendazole equine oral gel and were stalled for 24 h. The passed feces were thoroughly examined, searching for elimination of larvae. A total of 64% of the foals (n = 45/71) harbored Gasterophilus spp. larvae in the stomach. Mild hyperemia in the gastric mucosa was observed in the attachment sites of the parasites. Physical assessment and hematological parameters' data were analyzed with Shapiro-Wilk normality test. Comparison between groups for clinical signs, hematological parameters and Gasterophilus spp. infection rates were evaluated using the Kruskal-Wallis test or Student's t-test. Statistical significance was set at P < 0.05. There were no statistically significant variations in physical and hematological parameters between foals that were affected and those that were not infected. The larvae found in the feces were subjected to morphological examination, which confirmed the diagnosis of Gasterophilus intestinalis. No systemic clinical indications compatible with Gasterophilus spp. infestation were seen, as described in previous studies of horses infected with the parasite. No botfly eggs were observed in the hair of evaluated foals. During gastroscopy, mild hyperemic lesions in the gastric mucosa were observed in the larvae fixation sites. Although no changes in clinical or hematological parameters were noted, the confirmation of parasite presence is a cause for concern due to horses' tolerance for low infestation levels and poor diagnosis. Additionally, the presence of this myiasis in foals may be a significant stressor during the weaning period and should be included in the differential diagnosis of recurring abdominal pain. Furthermore, infected foals might be a reservoir for the parasite and, contribute to the elimination and spread of the larvae in the environment. Thus, inclusion of young horses in deworming protocols targeted to botfly larvae is needed. This is the first report of Gasterophilus intestinalis myiasis in foals in Brazil. Further research is necessary to fully understand the epidemiology and prevalence of this condition in young horses in Brazil, based on the findings of this study.(AU)

Development of a weight-estimation model to use in pregnant criollo-type mares / Modelo para estimativa de peso em éguas gestantes mestiças crioulas

The aims of this study were: 1) to compare the tape weight and associated weight-estimation formula to evaluate weight gain in pregnant mares, and 2) to develop a mathematical model to estimate the weight of pregnant mares using body measurements. Thirty-four criollo-type mares were evaluated every two weeks during the middle and late pregnancy. The mares were weighed on a livestock scale, and we estimated body weight using tape weights and an associated body-weight estimation formula. Also, heart-girth circumference (heartgirth) and abdominal circumference were measured; the latter at the 12th intercostal space (12th ICS) and 18th rib (18th Rib), to use in a mathematical model to estimate the weight of pregnant mares. Observations were divided into three periods of pregnancy: 5th to 7 h month, 7th to 9 h month, and 9th to 11th month. Mares in late pregnancy showed an increase in actual weight and an increase in 12th ICS and 18th Rib measurements. Tape weight and body-weight estimation formula underestimated the weight of pregnant mares. However, the regression model using heart-girth circumference, 12th ICS, and 18th Rib measurements showed high correlation (r2 = 0.87, P 0.001) with actual weight. Finally, the alternative methods usually used in horses are not accurate to estimate body weight in pregnant mares. In conclusion, the regression model Y=-540.143 + (heartgirth x 3.068) + (12th ICS x 1.278) + (18th Rib x 0.944) can be used to estimate body weight in pregnant mares from the 5th to 11th months of pregnancy.(AU)

Este estudo teve como objetivos: 1) comparar a utilização dos métodos alternativos fita de pesagem e peso metabólico em éguas gestantes e; 2) desenvolver um modelo matemático para estimar o peso de éguas gestantes, baseado em medidas corporais. Trinta e quatro éguas foram avaliadas quinzenalmente durante o terço médio e final da gestação. Foi realizada a pesagem em balança comercial; a mensuração com a fita de peso para equinos; o cálculo do peso metabólico; as medidas de perímetro torácico (Ptorac); a mensuração abdominal no décimo segundo espaço intercostal (12EI) e na décima oitava costela (18Cost). As observações foram divididas em três períodos gestacionais: Período de 5 a 7 meses, Período de 7 a 9 meses e Período de 9 a 11 meses. As éguas demonstraram incremento no peso na balança e na mensuração abdominal no 12EI e 18Cost no terço final da gestação. A utilização da fita de pesagem e o cálculo de peso metabólico subestimaram o peso na balança em éguas gestantes. O modelo de regressão utilizando o Ptorac, 12EI e 18Cost apresentou alta correção (r2=0,87; P 0,001) com o peso na balança. Observou-se que os métodos alternativos de pesagem, usualmente utilizados, não apresentaram a mesma eficiência em éguas prenhes. Pode-se concluir que o modelo de regressão Y=-540,143+(Ptorac X 3,068) + (12EI X 1,278) + (18Cost X 0,944) pode ser utilizado para mensurar o peso em éguas gestantes a partir do 5º mês de gestação.(AU)