Evaluation of reactivity of horses in the presence of unknown stimulus / Avaliação da reatividade de equinos na presença de estímulo sonoro desconhecido

The study aimed to evaluate reactivity of horses during usual brushing management against the repeated presence of an unknown sonorous stimulus. Twenty Mangalarga Marchador horses, distributed in different categories (mares and foals), were evaluated. The animals were allocated into the control treatment (N = 10) and the treatment with unknown sonorous stimulus (N = 10) from a rattle and a tambourine. Four consecutive evaluations were carried out first (day 0, 1, 2, 3). Two consecutive assessments were carried out after 30 days of the first collection (day 30 and 31), and two consecutive assessments were carried out 15 days after the second evaluation (day 45 and 46). The behavioral observations were made by assigning a score to behaviors of movement, position of ears and eyes, breathing, and vocalization during brushing management. A response variable called reactivity was attributed to each animal, ranging from score 1 (not reactive or calm animal) to reactivity score 4 (very reactive or aggressive animal). For statistical analysis, the results were adjusted to a logistic regression model using the categories, day, and treatment as covariates. The animals of the unknown stimuli showed greater reactivity. The days of the experimental period influenced the reactivity of animals between 6 and 7 months old, with a decrease in the possibilities of the animals to have a higher reactivity. The maturity of the foal with repeated exposure to the unknown sound stimulus may decrease the possibility of the animal being reactive.

O objetivo do presente estudo foi avaliar a reatividade de equinos durante o manejo habitual de escovação, frente à exposição repetida a um estímulo sonoro desconhecido. Para isto, foram utilizados 20 equinos da raça Mangalarga Marchador, de diferentes categorias (éguas e potros), os quais foram alocados aos tratamentos: controle (N = 10) e com estímulo sonoro desconhecido (N = 10), que consistia em confrontar os animais com o estímulo sonoro de um chocalho e um tamborim. Primeiramente, foram realizadas quatro avaliações consecutivas (dia 0, 1, 2, 3). Após 30 dias da primeira coleta, foram realizadas duas avaliações consecutivas (dia 30 e 31), e passados 15 dias desta, foram realizadas mais duas avaliações consecutivas (dia 45 e 46). As observações comportamentais foram feitas por meio da atribuição de escores aos comportamentos de movimentação, posição das orelhas e dos olhos, respiração e vocalização durante o manejo de escovação. Também foi conferida a variável resposta de reatividade com valores variando de 1 a 4 (animal não reativo ou calmo a animal muito reativo ou agressivo). Foi ajustado o modelo de regressão logística ordinal usando como covariáveis as categorias, dia e tratamento. A reatividade dos animais com estímulo sonoro desconhecido foi maior. Os dias do período experimental influenciaram a reatividade dos animais entre 6 e 7 meses de idade, com diminuição das chances dos animais desta idade apresentarem maior reatividade no decorrer dos dias. O amadurecimento do potro junto com a exposição repetida ao estímulo sonoro desconhecido podem diminuir a possibilidade de o animal ser reativo.

responses of horses to predator stimuli

It is not known whether the instincts of wild horses have remained strong during their centuries of domestication. Knowledge of this matter would give riders the opportunity to know more about the behavior of horses and consequently about safety for both horses and riders. In this current research, we studied the behavior of fifteen Caspian miniature horses of different ages and sexes using stimuli from predators under standardized conditions. We explored whether olfactory [lion feces] or auditory [lion roars] stimuli affected horses to a greater extent. The test arena was an appropriately equipped grass paddock, in which horses spent between 5 and 8 min. The experiments were designed to investigate behavioral responses in locomotive activity [alertness, standing, walking, trotting, exploration and other], eliminatory behavior [defecation, urination] and physiological responses [heart rates before and after the predator stimuli] of horses to novel auditory and olfactory stimuli. In the olfactory experiment, we found that the horses showed significantly more behavioral reactions compared to the control experiment [where horses were not exposed to any stimuli]; the only behavioral reaction the horses did not show was flight reaction. Additionally, heart rate was significantly increased after olfactory stimuli compared to auditory stimuli. In the auditory experiment, we found that horses showed more behavioral reactions in response to the roar of the lion compared to the olfactory stimulus, including flight reactions. We concluded that the auditory stimuli caused significantly higher heart rate responses when compared to the olfactory stimuli