The swine industry has been successful in achieving hyperprolificity over the years [1], [2]. However, this achievement has led to challenges in the farrowing process, particularly in terms of duration and newborn performance [2], [3], [4], [5]. These complications impact piglet survival and cause risks to uterine health and affect colostrum yield, which is crucial for overall reproductive success [6], [7], [8]. Prolonged farrowing can lead to hypoxia, resulting in stillborns and low-vitality newborns that are more prone to mortality [4], [9], [10], [11], [12]. In addition, approximately 15%–20% of the total piglets born do not survive during farrowing or within the first days of life [10], [13]. Hence, focusing on this critical period and understanding the farrowing process is essential to enhance reproductive outcomes [14].

The administration of uterotonics (oxytocin and carbetocin) is commonly used to shorten the farrowing duration because it causes more frequent, intense, and longer uterine contraction, leading to a shorter farrowing duration [15]. However, their usage must be carefully considered due to the increased myometrial activity that can disrupt the oxytocin-related axis, leading to a restriction of blood flow to the uterus, which may result in fetal stress, hypoxia, and the occurrence of fetal deaths [15], [16], [17]. Hence, other strategies to improve farrowing performance besides uterotonics have been studied, such as controlling pain and stress factors [7], [17].

According to Blavi et al. [18], farrowing induces visceral pain as a result of uterine and cervical dilation, which can be exacerbated by dystocia. On the other hand, pain and stress can delay the farrowing process due to the opioid-mediated reduction in oxytocin release [19], [20], [21], [22]. In this way, anti-inflammatory drugs, especially steroids, have demonstrated efficacy in controlling pain [17] and could mitigate the adverse effects of stress and pain if administered around parturition. Additionally, glucocorticoids have a complex and important role in myometrial contraction during parturition [23], [24]. Glucocorticoids prepare the myometrium for contraction by transitioning it from an inert state to a contractile state, upregulating the expression of contraction-associated proteins in the myometrium, and enhancing the synthesis of prostaglandins E2 and F2α [23], [24]. These mechanisms further promote myometrial contraction and the progression of parturition. Therefore, we hypothesized that administering dexamethasone (a potent synthetic glucocorticoid) in the periparturient sow could improve the farrowing process.

Dexamethasone is known for its potent anti-inflammatory properties and extended biological half-life of 36–72 hours, making its effects last beyond the expulsive stage of farrowing [25], [26], [27], when administered at onset of farrowing. Therefore, glucocorticoids can reduce inflammation in various sites, including the mammary gland, thus potentially improving colostrum yield and quality by decreasing the levels of pro-inflammatory cytokine TNF-α [28], [29], [30]. Moreover, glucocorticoids are important mediators of lactogenesis [28], stimulating ultrastructural components essential for milk synthesis and secretion and controlling the expression of genes involved in milk protein regulation [31]. In this way, Ward et al. [32] observed alterations in colostrum protein content with dexamethasone administration before farrowing. These findings underscore the significant role of dexamethasone in regulating lactation dynamics and emphasize its potential implications for colostrum production and composition, especially regarding immunoglobulins.

Additionally, to the potential mechanism of dexamethasone on parturition and lactational performance previously described, recently, we found a reduction in farrowing duration when primiparous sows were treated with dexamethasone before farrowing onset, without differences in piglet performance [33]. However, unlike primiparous sows, multiparous sows often face increased challenges during farrowing, such as higher frequency of prolonged farrowing and higher odds of stillbirth [34], [35], which may impact positively their response to dexamethasone treatment. Therefore, this study aimed to investigate the potential benefits of dexamethasone treatment specifically in multiparous sows during the periparturient phase, focusing on both farrowing and newborn piglet performance. Specifically, we sought to determine whether dexamethasone treatment (20 mg im per female) could replicate the observed reduction in farrowing duration in multiparous as found in primiparous sows [33]. Additionally, we aimed to assess its potential to reduce stillbirth rates and improve newborn piglet traits (vitality, glycemia, meconium staining, among others), overall performance, and survival of newborn piglets up to 5 days of age.