Ear Movements Research Articles

Computational investigation of the social function of domestic cat facial signals.

There is growing interest in the facial signals of domestic cats. Domestication may have shifted feline social dynamics towards a greater emphasis on facial signals that promote affiliative bonding. Most studies have focused on cat facial signals during human interactions or in response to pain. Research on intraspecific facial communication in cats has predominantly examined non-affiliative social interactions. A recent study by Scott and Florkiewicz1 demonstrated significant differences between cats' facial signals during affiliative and non-affiliative intraspecific interactions. This follow-up study applies computational approaches to make two main contributions. First, we develop a machine learning classifier for affiliative/non-affiliative interactions based on manual CatFACS codings and automatically detected facial landmarks, reaching above 77% in CatFACS codings and 68% in landmarks by integrating a temporal dimension. Secondly, we introduce novel measures for rapid facial mimicry based on CatFACS coding. Our analysis suggests that domestic cats exhibit more rapid facial mimicry in affiliative contexts than non-affiliative ones, which is consistent with the proposed function of mimicry. Moreover, we found that ear movements (such as EAD103 and EAD104) are highly prone to rapid facial mimicry. Our research introduces new possibilities for analyzing cat facial signals and exploring shared moods with innovative AI-based approaches.

Differences in behaviour, facial expressions and locomotion between positive anticipation and frustration in horses

Animal welfare is a result of accumulated negative and positive emotions. Therefore, it is important to limit the former and promote the latter. Doing so requires a precise identification of these emotions. The aim of this study was to characterize the behaviours, facial expressions and locomotor parameters of 21 horses in two conditions with opposite valence, presumed to induce positive anticipation and frustration. In the positive anticipation situation, the horse was led to a bucket of food, knowing that they would be allowed to eat it. In the frustration situation, experimenters indicated to the horse that food was available without allowing them to eat it. In the positive anticipation situation, horses exhibited a lower neck position with the ears forward and upper lip advanced and went faster by increasing their stride frequency accompanied by increased global locomotor activity. In the frustration situation, horses exhibited a higher neck position with the ears backward or to the side, accompanied by ear movements and eye blinks, and interacted more with the experimenters. This study describes new possible indicators of positive anticipations and frustration in horses.

Caudal auricular muscle variations and the evolution of echolocation behavior in pteropodid bats.

Among bats, rhinolophoids and yangochiropterans, but not pteropodids, exhibit laryngeal echolocation. Although Rousettus has been regarded as the only pteropodid capable of echolocation using tongue clicks, recent evidence suggests that other species of pteropodids are also capable of echolocation using wing clicks. Studies on laryngeal echolocators suggest that delicate ear movements are essential for the echolocation behavior of bats and that the cervicoauricularis muscles play a critical role in such ear movements. In this study, we observed the gross anatomy of cervicoauricularis muscles in three species of pteropodids (Cynopterus sphinx, Eonycteris spelaea, and Rousettus leschenaultii) to examine whether ear muscle anatomy varies among pteropodids with different echolocation types and between pteropodids and laryngeal echolocating bats. We found that M. cervicoauricularis profundus originates from the nuchal crest in tongue-click echolocators (R. leschenaultii) and from the midline in wing-click echolocators (C. sphinx and E. spelaea). In general, tongue-click echolocation using high click rates is considered to be more sophisticated in terms of sonar performance than wing-click echolocation. M. cervicoauricularis profundus originating from the nuchal crest (CPNC) is not common in non-bat laurasiatherian mammals, but can be found in laryngeal echolocating bats. As it pulls the ear pinna caudally in the horizontal plane and increases the access to sound, CPNC found in R. leschenaultii and laryngeal echolocating bats may be a key characteristic of the sophisticated active echolocation behavior of bats.

Anatomy and homology of the caudal auricular muscles in greater short-nosed fruit bat (Cynopterus sphinx).

Bats can be phylogenetically classified into three major groups: pteropodids, rhinolophoids, and yangochiropterans. While rhinolophoids and yangochiropterans are capable of laryngeal echolocation, pteropodids lack this ability. Delicate ear movements are essential for echolocation behavior in bats with laryngeal echolocation. Caudal auricular muscles, especially the cervicoauricularis group, play a critical role in such ear movements. Previously, caudal auricular muscles were studied in three species of bats with laryngeal echolocation, but to our knowledge, there have been no studies on non-laryngeal echolocators, the pteropodids. Here, we describe the gross anatomy of the cervicoauricularis muscles and their innervation in Cynopterus sphinx by using diffusible iodine-based contrast-enhanced computed tomography and 3D reconstructions of immunohistochemically stained serial sections. A previous study on bats with laryngeal echolocation reported that rhinolophoids have four cervicoauricularis muscles and yangochiropterans have three. We observed three cervicoauricularis muscles in the pteropodid C. sphinx. The number of cervicoauricularis muscles and their innervation pattern were comparable to those of non-bat boreoeutherian mammals and yangochiropterans, suggesting that pteropodids, and yangochiropterans maintain the general condition of boreoeutherian mammals and that rhinolophoids have a derived condition. The unique nomenclature had been previously applied to the cervicoauricularis muscles of bats with laryngeal echolocation, but given the commonality between non-bat laurasiatherians and bats, with the exception of rhinolophoids, maintaining the conventional nomenclature (i.e., M. cervicoauricularis superficialis, M. cervicoauricularis medius, and M. cervicoauricularis profundus) is proposed for bats.

Greater Horseshoe Bats Recognize the Sex and Individual Identity of Conspecifics from Their Echolocation Calls.

The echolocation calls of bats are mainly used for navigation and foraging; however, they may also contain social information about the emitter and facilitate social interactions. In this study, we recorded the echolocation calls of greater horseshoe bats (Rhinolophus ferrumequinum) and analyzed the acoustic parameter differences between the sexes and among individuals. Then, we performed habituation-discrimination playback experiments to test whether greater horseshoe bats could recognize the sex and individual identity of conspecifics from their echolocation calls. The results showed that there were significant differences in the echolocation call parameters between sexes and among individuals. When we switched playback files from a habituated stimuli to a dishabituated stimuli, the tested bats exhibited obvious behavioral responses, including nodding, ear or body movement, and echolocation emission. The results showed that R. ferrumequinum can recognize the sex and individual identity of conspecifics from their echolocation calls alone, which indicates that the echolocation calls of R. ferrumequinum may have potential communication functions. The results of this study improve our understanding of the communication function of the echolocation calls of bats.

Feeding behaviour and activity of beef calves during the first week at the feedlot: Impact of calf source and commingling ratios

Preconditioned (PC) calves have reduced morbidity, mortality and improved performance compared to auction-derived (AD) and non-preconditioned calves; however, there is limited research on the impacts of commingling PC and AD calves at the feedlot. Commingling calves from various sources is known to be highly stressful and can impact performance on arrival at the feedlot. Therefore, the first objective was to assess feeding behaviour (time spent eating and ruminating) and activity of PC beef calves during the first 7 days after arrival at the feedlot compared to ranch-sourced (RS) and AD calves. The second objective was to assess the impacts of commingling PC calves with various proportions of AD calves (25, 50, 75 %) on feeding behaviour and activity in that same time frame. A subset of 45 calves per pen for PC, AD, and commingled pens, and 20 RS calves were equipped with CowManager® tags on arrival. This technology detects ear movement through a sensor in the tag linked to eating, ruminating, active and not active. On average, in the first 7 days at the feedlot, PC calves spent 11 % more time eating than RS and 15 % more time than AD calves. PC calves spent 5 % less time active compared to RS (P < 0.000), and there was no significant difference in activity compared to AD. PC calves spent 4 % less time not active compared to RS (P = 0.017) and 15 % less time inactive compared to AD calves (P < 0.001). There was no difference among PC, RS and AD in overall time spent ruminating. When comparing PC calves from 100 % PC and commingled pens, 100 % PC calves spent 5 % more time eating compared to a 75 % ratio PC and 5 % more time eating compared to a 25 % ratio PC pen. However, time spent eating was not significantly different between 100 % PC and 50 % ratio PC. Furthermore, PC calves had increased time spent eating and less time spent active and not active during the first 7 days after arrival at the feedlot compared to RS and AD calves. When commingled with AD calves, PC calves had more time spent eating and reduced time spent active and not active; therefore, PC calves have exhibited increased feeding behaviour also after being commingled with AD calves at the feedlot. The current study acknowledges the limitations of the field experiment that not all confounding variables could be controlled for, explicitly pen effect due to the lack of replication of pens across groups.

Theoretical investigation of active listening behavior based on the echolocation of CF-FM bats.

Bats perceive the three-dimensional environment by emitting ultrasound pulses from their nose or mouth and receiving echoes through both ears. To determine the position of a target object, it is necessary to know the distance and direction of the target. Certain bat species that use a combined signal of long constant frequency and short frequency modulated ultrasounds synchronize their pinnae movement with pulse emission, and this behavior has been regarded as helpful for localizing the elevation angle of a reflective sound source. However, the significance of bats' ear motions remains unclear. In this study, we construct a model of an active listening system including the motion of the ears, and conduct mathematical investigations to clarify the importance of ear motion in direction detection of the reflective sound source. In the simulations, direction detection under rigid ear movements with interaural level differences was mathematically investigated by assuming that bats accomplish direction detection using the amplitude modulation in the echoes caused by ear movements. In particular, the ear motion conditions required for direction detection are theoretically investigated through exhaustive simulations of the pseudo-motion of the ears, rather than simulations of the actual ear motions of bats. The theory suggests that only certain ear motions, namely three-axis rotation, allow for accurate and robust direction detection. Our theoretical analysis also strongly supports the behavior whereby bats move their pinnae in the antiphase mode. In addition, we suggest that simple shaped hearing directionality and well-selected uncomplicated ear motions are sufficient to achieve precise and robust direction detection. Our findings and mathematical approach have the potential to be used in the design of active sensing systems in various engineering fields.

Facial Expressions of Horses Using Weighted Multivariate Statistics for Assessment of Subtle Local Pain Induced by Polylactide-Based Polymers Implanted Subcutaneously.

Simple SummaryFacial expression (FE) has been used for pain diagnosis in horses. The current study aimed to identify pain in horses undergoing under-skin polylactide-based polymer implantation. Five statistical methods for analyzing FE were used, including conventional and new approaches. First, we scored the seven FEs separately. Subsequently, the scores of the seven FEs were added (SUM). Subsequently, principal component analysis (PCoA) was performed using the scores of the seven FEs obtained using the first method. Afterwards, weights were created for each FE based on each variable’s contribution variability obtained from the PCoA (SUM.W). Finally, we applied a general score to the animal’s face (GFS). The horses were filmed before and 24 and 48 h after implantation. The tissue sensitivity to mechanical stimulation and skin temperature of the horses were assessed at the same time points. The results show no changes in the FEs analyzed separately or jointly. The horses with incision and suture but no polymer implant displayed a higher pain-related FE 48 h after implantation, while the horses implanted with polymers displayed more apparent alterations in the mechanical skin sensitivity and temperature. Our findings show that the five statistical methods used to analyze the faces of the horses were not able to detect low-grade inflammatory pain.Facial-expression-based analysis has been widely applied as a pain coding system in horses. Herein, we aimed to identify pain in horses undergoing subcutaneously polylactide-based polymer implantation. The sham group was submitted only to surgical incision. The horses were filmed before and 24 and 48 h after implantation. Five statistical methods for evaluating their facial expressions (FEs) were tested. Primarily, three levels of scores (0, 1, and 2) were applied to the seven FEs (ear movements, eyebrow tension, orbicularis tension, dilated nostrils, eye opening, muzzle tension, and masticatory muscles tension). Subsequently, the scores of the seven FEs were added (SUM). Afterwards, principal component analysis (PCoA) was performed using the scores of the seven FEs obtained using the first method. Subsequently, weights were created for each FE, based on each variable’s contribution variability obtained from the PCoA (SUM.W). Lastly, we applied a general score (GFS) to the animal’s face (0 = without pain; 1 = moderate pain; 2 = severe pain). The mechanical nociceptive threshold (MNT) and cutaneous temperature (CT) values were collected at the same moments. The results show no intra- or intergroup differences, when evaluating each FE separately or in the GFS. In the intragroup comparison and 48 h after implantation, the control group showed higher values for SUM, PCoA, and SUM.W, although the horses implanted with polymers displayed more obvious alterations in the CT and MNT. Our findings show that the five statistical strategies used to analyze the faces of the horses were not able to detect low-grade inflammatory pain.

Axonal Regeneration Through Autologous Grafts: Does the Axonal Load Influence Regeneration?

IntroductionTwo-stage free functional muscle transfers for long-standing facial palsy can yield unpredictable results. Earlier studies have demonstrated incomplete regeneration across neurorrhaphies in native nerve and higher donor axonal counts correlating with improved outcomes but axonal count in nerve grafts have not been as thoroughly reviewed. To investigate the impact of varying axonal counts in autologous grafts on functional outcomes of repair. Materials and methodsAnimals were allocated into three groups: Direct Nerve Repair (DNR, n = 50), Small Nerve Graft (SNG, n = 50), and Large Nerve Graft (LNG, n = 50). All grafts were inset into the Posterior Auricular Nerve with ear movement recovery (EMR) monitored as functional outcome. At various postoperative weeks (POWs), excised specimens were imaged with electron microscopy. Axonal counts were measured proximal to, distal (DAC) to, and within grafts. Total Success Ratio (TSR) was calculated. ResultsIn DNR, DAC was significantly lower than proximal axonal counts at all POWs, with maximum TSR of 80%. TSR for LNG and SNG were significantly lower at all POWs when compared to DNR, with maximums of 56% and 38%, respectively. LNG had a significantly larger DAC than SNG at POW12 and beyond. A direct relationship was present between DAC and EMR for all values. ConclusionsHigher native axonal count of autologous nerve grafts resulted in higher percentage of regeneration across neurorrhaphies.

Vocalization and other behaviors as indicators of emotional valence: The case of cow-calf separation and reunion in beef cattle

Vocalization may communicate the emotional state in vocal animals. We aimed to describe and compare vocalization and other behavioral signs of cow-calf pairs in emotionally negative and positive situations, and the potential influence of genetic group, parity category and calf sex on these signs.Forty-two beef cows (16 primiparous and 26 multiparous), and their 24 h-old calves (24 males and 18 females), with no previous separation from their mothers, were studied in Southern Brazil. The dams were daughters of Taurine crossbred mothers, 16 with Limousin (LIMO), 15 Charolais (CHAR), six Brahman (BRAH) and five Blond d'Aquitaine (BLON) bulls. We recorded 3 minute-videos to analyse animal responses to three sequential treatments: AR – arrival of cow and calf together in corral one (C1); SE – separation of the pair, calf removal from C1, isolated in corral 2 (C2), not seeing but hearing the cow; RU – reunion of calf and mother in C1. For cows and calves, the vocalization count per minute, fundamental frequency (f0), duration of the vocal call and latency to vocal response in AR, SE and RU were measured, as well as selected behaviour signals. A significant interaction effect between treatment and genetic group was observed for duration, pitch and vocalization count per minute. In SE, LIMO and CHAR cows expressed longer vocal responses than during AR, 24.6% and 18.2%, respectively, and RU (LIMO 15.7% and CHAR 33.6%). In SE, LIMO (114.2Hz) and BRAH (124.6Hz) cows showed higher f(0). CHAR and BRAH cows vocalized 2.8 and 5.1 times more frequently during SE than RU. Cows showed higher frequency of tail movements and smelling the corral in SE than in AR and RU. Cows presented higher frequency of head movement in SE as compared with RU. Calves showed greater head and body movement during SE than during AR and RU. In SE, male calves showed higher frequency of ear movements than female calves. Body movements of the cow were also more frequent during SE than in RU. Overall, cows showed higher pitch, longer vocal calls and other behavioral changes in SE, such as tail flapping, sniffing the corral, and head and body movements; calves showed higher frequency of head and body movement in SE. The results suggest that the studied indicators may be useful to identify emotionally negative situations, with genetic group and calf sex as factors which deserve further studies.

Development and preliminary validation of a pain scale for ophthalmic pain in horses: The Equine Ophthalmic Pain Scale (EOPS)

The purpose of this study was to describe the development and preliminary validation of a composite pain scale, called the Equine Ophthalmic Pain Scale (EOPS), to assess ocular pain in horses. Indicators associated with ocular pain were selected and classified as behavioural, physiological or ocular expressions. Eight horses diagnosed with ocular or adnexa diseases that required medical or surgical treatment were enrolled in the study (group P). The developed EOPS was applied at the baseline (T0) and 1 week later (T7). Moreover, the EOPS was applied twice, 1 week apart, to 15 healthy control horses (group C). Videos of 60−80 s duration of all assessments were retrospectively analysed by seven masked observers, who scored items included in the behavioural and ocular expression categories of the EOPS.The inter- and intra-observer reliability was excellent (intraclass correlation coefficients ≥0.75) for most of the scored items. Cronbach’s alpha (0.76) indicated that the EOPS had good internal consistency. The total score (TS), calculated as the sum of all scores, differed between groups C and P at T0 (P < 0.001) and reduced after medical/surgical treatment in group P (P = 0.017), indicating the responsiveness of the EOPS. Moreover, the area under the curve (AUC=0.918, 95% confidence interval = 0.815–1.000; P < 0.001) indicated that the EOPS was very accurate for distinguishing healthy from pathological animals. Sensitivity and specificity of EOPS to identify horses with ocular pathology (at the optimal cut-off, i.e. TS ≥ 7) were 81.3% and 100.0%, respectively. However, ‘overall behaviour’, ‘position inside the box’, ‘ear movements’ and ‘head position’ items as well as physiological parameters, showed sub-optimal reliability, consistency and/or item-total correlation, suggesting that there is still room to improve this composite scale.

Effect of transportation and social isolation on facial expressions of healthy horses.

Horses have the ability to generate a remarkable repertoire of facial expressions, some of which have been linked to the affective component of pain. This study describes the facial expressions in healthy horses free of pain before and during transportation and social isolation, which are putatively stressful but ordinary management procedures. Transportation was performed in 28 horses by subjecting them to short-term road transport in a horse trailer. A subgroup (n = 10) of these horses was also subjected to short-term social isolation. During all procedures, a body-mounted, remote-controlled heart rate monitor provided continuous heart rate measurements. The horses’ heads were video-recorded during the interventions. An exhaustive dataset was generated from the selected video clips of all possible facial action units and action descriptors, time of emergency, duration, and frequency according to the Equine Facial Action Coding System (EquiFACS). Heart rate increased during both interventions (p<0.01), confirming that they caused disruption in sympato-vagal balance. Using the current method for ascribing certain action units (AUs) to specific emotional states in humans and a novel data-driven co-occurrence method, the following facial traits were observed during both interventions: eye white increase (p<0.001), nostril dilator (p<0.001), upper eyelid raiser (p<0.001), inner brow raiser (p = 0.042), tongue show (p<0.001). Increases in ‘ear flicker’ (p<0.001) and blink frequency (p<0.001) were also seen. These facial actions were used to train a machine-learning classifier to discriminate between the high-arousal interventions and calm horses, which achieved at most 79% accuracy. Most facial features identified correspond well with previous findings on behaviors of stressed horses, for example flared nostrils, repetitive mouth behaviors, increased eye white, tongue show, and ear movements. Several features identified in this study of pain-free horses, such as dilated nostrils, eye white increase, and inner brow raiser, are used as indicators of pain in some face-based pain assessment tools. In order to increase performance parameters in pain assessment tools, the relations between facial expressions of stress and pain should be studied further.

Facial musculature in naked mole‐rats ( Heterocephalus glaber )

Naked mole-rats (Heterocephalus glaber) are fossorial rodents with an unusually long-life span and eusocial niche. They are from the Bathyergidae family and their unusual anatomical and physiological traits, including several adaptations to their fossorial and eusocial niche, have been relatively under-studied compared to other rodent species. Their adaptations to a subterranean niche and eusociality are demonstrated by their large incisors, oral folds, and highly developed tactile system (incisors and tactile hairs covering their body). Naked mole-rats utilize their large incisors for social interacting, defense, navigation, object manipulation, feeding, and digging. Their oral folds close caudal to their incisors to prevent dirt from entering their oral cavity while digging. Their well-developed tactile system compensates for their reduced visual (functionally blind) and auditory systems (reduced pinnae). Naked mole-rat facial musculature would also be expected to have evolved and express neotenic features as an adaption to a fossorial niche. There are few studies that have characterized facial musculature in naked mole-rats. Therefore, we performed detailed facial muscle dissections of adult naked mole-rats, which included the presence and attachment sites. We compared our dissections with comparative anatomical studies. Our dissections showed subterranean adaptations to face musculature in naked mole-rates, including reduced musculature associated with ear and eye movements. Further, our findings provide insight into the ecological and evolutionary adaptations of naked mole-rat facial musculature to a subterranean niche.

Post-operative pain behaviour associated with surgical castration in donkeys (Equus asinus).

BackgroundRecognising pain in donkeys is challenging because they are stoic.ObjectivesTo identify the responses of donkeys before and after surgical pain.Study designProspective, short‐term longitudinal pre‐ and post‐intervention observations.MethodsForty adult donkeys underwent surgical castration after sedation with intravenous (IV) xylazine, induction with guaiphenesin/thiopental IV and maintenance of anaesthesia with isoflurane and local anaesthetic blockade. Four hours after recovery from anaesthesia, flunixin meglumine 1.1 mg/kg, dipyrone 10 mg/kg and morphine 0.2 mg/kg IV were administered. Behavioural responses exhibited by the animals housed in individual stalls were recorded in four 30‐min videos: before castration (M0), and 3.5‐4.0 hours (M1), 5.5‐6.0 hours (M2) and 23.5‐24.0 hours after recovery from anaesthesia (M3). To exclude the influence of insects, the behaviour of six apparently pain‐free donkeys was compared with and without the presence of faeces and urine in the stall.ResultsWhen compared with presurgical baseline behaviours (M0), after surgery (M1) donkeys raised their pelvic limbs more (P = .003). When compared with M1, after analgesia (M2), the median frequencies of ear movements (44 vs 16; P < .001), head shaking (7 vs 1; P < .001), head turning (5 vs 0; P < .001) and lifting of the both limbs (7 vs 0; P = .008) decreased; feeding (0 vs 29; P < .001) and water intake (0 vs 0, range 0‐1 vs 0‐7; P = .05) increased. The dirty stall increased tail (53 vs 80; P = .03), head (16 vs 30; P = .03) and ear movements (50 vs 78; P = .04).Main limitationsThe dirty stall and presence of insects possibly contributed to the expression of behaviours unrelated to pain.ConclusionLifting the pelvic limbs was the only specific pain behaviour after castration in donkeys. Analgesia restored appetite and water intake and reduced the frequency of head shaking and turning, ear movement and lifting the limbs. Tail, head and ear movements are unspecific responses related both to pain and a dirty stall, and are confounding factors when pain is assessed in donkeys in the presence of insects.

Adaptive Echolocation and Flight Behaviors in Bats Can Inspire Technology Innovations for Sonar Tracking and Interception

Target tracking and interception in a dynamic world proves to be a fundamental challenge faced by both animals and artificial systems. To track moving objects under natural conditions, agents must employ strategies to mitigate interference and conditions of uncertainty. Animal studies of prey tracking and capture reveal biological solutions, which can inspire new technologies, particularly for operations in complex and noisy environments. By reviewing research on target tracking and interception by echolocating bats, we aim to highlight biological solutions that could inform new approaches to artificial sonar tracking and navigation systems. Most bat species use wideband echolocation signals to navigate dense forests and hunt for evasive insects in the dark. Importantly, bats exhibit rapid adaptations in flight trajectory, sonar beam aim, and echolocation signal design, which appear to be key to the success of these animals in a variety of tasks. The rich suite of adaptive behaviors of echolocating bats could be leveraged in new sonar tracking technologies by implementing dynamic sensorimotor feedback control of wideband sonar signal design, head, and ear movements.

Musculature of the head and neck in naked mole‐rats (Heterocephalus glaber)

Naked mole‐rats (Heterocephalus glaber) are eusocial, subterranean rodents from the family Bathyergidae. Their unusual anatomical and physiological traits, including a number of adaptations to their fossorial and eusocial niche, have been relatively under‐studied compared to other rodent species. They have large incisors that are used for social interactions (as well as defense); for navigation and object manipulation; for feeding; and for digging complex tunnel systems. In addition, naked mole‐rats have unusual oral folds that close caudal to their incisors, preventing dirt from entering their oral cavity while digging. They are functionally blind and have reduced pinnae. However, their well‐developed tactile system ‐ relying on their incisors as well as tactile hairs covering the entire body ‐ compensates for their reduced visual and auditory systems.Naked mole‐rat head and neck musculature might also be expected to have adapted to a subterranean niche and present with neotenic features. However, few studies to date have characterized naked mole‐rat musculature. To address this, we performed detailed anatomical dissections on adult naked mole‐rats in order to investigate the presence and attachment sites of the head and neck musculature. We found adaptations to a subterranean niche. For example, musculature associated with ear and eye movements was reduced. Overall, our findings provide insight into head and neck musculature as they relate to ecological and evolutionary adaptations, which can be placed within a comparative anatomical context based on what is present in other species.

Evidence of Pain, Stress, and Fear of Humans During Tail Docking and the Next Four Weeks in Piglets (Sus scrofa domesticus).

Tail docking is widely performed in pig farms to prevent tail biting. We investigated the consequences of this practice on behavioral indicators of pain and stress, and on the human-piglet relationship during lactation. Within 19 litters, piglets (1–3 days of age) were submitted on day 0 (D0) to docking with a cautery iron (D), sham-docking (S), or no docking (U). Piglets from the D and S groups were observed during the procedure (body movements and vocalizations) and just after, in isolation, during 20 s for body, tail and ear postures as well as ear movements. Piglets from the three treatments were observed in their home pen after docking on D0 and D3 afternoon for body posture, tail posture and movements. Piglets from the D and U groups were observed on D6, D12, D19, and D26 in their home pen for oral behavior, body, and tail posture. Tail damage and tear staining were scored on D5, D11, D18, and D25. A 5-min motionless human test was performed on D14. During the procedure, D piglets screamed more and with a higher intensity (P < 0.05) than S piglets (n = 48–50). Just after docking, D piglets held their ears in a posture perpendicular to the head-tail axis and changed their ear posture more often (P < 0.05). Between D6 and D26, D piglets kept their tail immobile (P < 0.001) and in a horizontal position (P < 0.01) more often than U piglets (n = 45–47). Between D11 and D25, U piglets had higher scores for tail damage and damage freshness than D piglets (0.09 < P < 0.02) whereas tear-stain score was similar. In the human test, D piglets interacted later with an unfamiliar human than U piglets (P = 0.01, n = 18/group). Present data indicate signs of acute pain and stress in piglets due to docking during the procedure itself and adverse consequences throughout lactation thereafter, including on their relationship with humans. On the other hand, the presence of tail lesions shows that undocked piglets are subject to more tail biting, even before weaning.

Behavioural and cardiovascular effects of medetomidine constant rate infusion compared with detomidine for standing sedation in horses

ObjectiveTo compare the efficacy of a medetomidine constant rate infusion (CRI) with a detomidine CRI for standing sedation in horses undergoing high dose rate brachytherapy. Study designRandomized, controlled, crossover, blinded clinical trial. AnimalsA total of 50 horses with owner consent, excluding stallions. MethodsEach horse was sedated with intravenous acepromazine (0.02 mg kg–1), followed by an α2-adrenoceptor agonist 30 minutes later and then by butorphanol (0.1 mg kg–1) 5 minutes later. A CRI of the same α2-adrenoceptor agonist was started 10 minutes after butorphanol administration and maintained for the treatment duration. Treatments were given 1 week apart. Each horse was sedated with detomidine (bolus dose, 10 μg kg–1; CRI, 6 μg kg–1 hour–1) or medetomidine (bolus dose, 5 μg kg–1; CRI, 3.5 μg kg–1 hour–1). If sedation was inadequate, a quarter of the initial bolus of the α2-adrenoceptor agonist was administered. Heart rate (HR) was measured via electrocardiography, and sedation and behaviour evaluated using a previously published scale. Between treatments, behaviour scores were compared using a Wilcoxon signed-rank test, frequencies of arrhythmias with chi-square tests, and HR with two-tailed paired t tests. A p value <0.05 indicated statistical significance. ResultsTotal treatment time for medetomidine was longer than that for detomidine (p = 0.04), and ear movements during medetomidine sedation were more numerous than those during detomidine sedation (p = 0.03), suggesting there may be a subtle difference in the depth of sedation. No significant differences in HR were found between treatments (p ≥ 0.09). Several horses had arrhythmias, with no difference in their frequency between the two infusions. Conclusions and clinical relevanceMedetomidine at this dose rate may produce less sedation than detomidine. Further studies are required to evaluate any clinical advantages to either drug, or whether a different CRI may be more appropriate.

Are Tail and Ear Movements Indicators of Emotions in Tail-Docked Pigs in Response to Environmental Enrichment?

Simple SummaryThe assessment of animal welfare should involve physical and mental welfare. Physical welfare is relatively easy to measure. Nevertheless, there is a lack of feasible indicators of positive emotions in farm animals, which causes difficulties in obtaining a complete analysis of welfare. To improve the quality of life of farm animals, it is necessary to be able to assess their welfare in a valid and feasible way. This study aimed to determine whether environmental enrichment, understood to be positive for animal welfare, could influence tail movement and ear movement in fattening pigs. These indicators could be used to assess emotions, with positive or negative valences, as suggested in previous studies on mini-pigs and pigs. The results showed that tail movement was a valid and feasible indicator of positive emotions; pigs moved their tails a greater number of times when they interacted more with enrichment than when they interacted less with it. Regarding ear movements, this study revealed a need for further investigation. This research could play an important role in improving the analysis of different emotions in pigs, thereby improving the assessment of animal welfare in pig breeding systems using valid, feasible, and noninvasive indicators of emotions. The inclusion of emotional indicators in farm monitoring methods can improve welfare assessments. Studies in controlled conditions have suggested that increased tail movement is an indicator of positive emotions in pigs, while others have proposed that increased ear movements are linked to negative emotions. This study aimed to investigate these indicators in pig farm conditions to analyze their validity and the effect of enrichment on welfare. Thirty-six pigs received one of the following enrichment materials: straw in a rack, wooden logs, or chains. Behavioral observations were performed by focal sampling. The results showed that tail movement duration was significantly higher when pigs exhibited “high use” (three or more pigs in a pen interacting with the enrichment) than when they exhibited “low use” (fewer than three) of enrichment (p = 0.04). A positive correlation was found between tail movement frequency and duration (r = 0.88; p = 0.02). The increase in tail movement could be considered an indicator of positive emotions in pigs when measured with other categories of indicators. Regarding ear movements, no significant difference was found. Future studies should further investigate these indicators thoroughly, as the results could be useful for improving the assessment of emotions in pigs.

Mobile Wireless Low-intensity Transcranial Ultrasound Stimulation System for Freely Behaving Small Animals.

Transcranial ultrasound stimulation (tUS) is a promising noninvasive approach to modulate brain circuits. While low-intensity tUS is putatively safe and has already been used for human participants, pre-clinical studies that aim to determine the effects of tUS on the brain still need to be carried out. Conventional tUS stimulation, however, requires the use of the anesthetized or immobilized animal model, which can place considerable restrictions on behavior. Thus, this work presents a portable, low cost, wireless system to achieve ultrasound brain stimulation in freely behaving animals. The tUS system was developed based on a commercial 16 MHz microcontroller and amplifier circuit. The acoustic wave with a central frequency of 450 kHz was generated from a 5mm PZT with a peak pressure of 426 kPa. The wireless tUS with a total weight of 20 g was placed on the back of the rat allowing the animal a full range of unimpeded motion. The mobile ultrasound system was able to induce a robust ear movement as a response to stimulation of the motor cortex. The outcome demonstrates the ability of wireless tUS to modulate the brain circuit of a freely behaving rat. The portability of the whole system provides a more natural environment for investigating the effect of tUS on behavior and chronic studies.