Juliana Zapata Cardona

Axolotls ( Ambystoma mexicanum ) are neotenic salamanders widely used as experimental models in regenerative biology, developmental research, toxicology, and pharmacology. Despite their extensive use in laboratory research and conservation programs, standardized necropsy procedures for this species remain limited and poorly documented. The absence of systematic protocols limits the consistency of postmortem examinations and complicates the interpretation of pathological findings in both experimental and diagnostic contexts. Here, we present a detailed and reproducible necropsy protocol for the neotenic axolotl based on 17 systematic necropsies performed under controlled laboratory conditions. The procedure describes step‐by‐step methods for external examination, access to the cranial cavity, exposure of the spinal cord, and systematic exploration of the coelomic cavity. Particular emphasis is placed on anatomical orientation, preservation of organ relationships, and strategies to minimize tissue damage during dissection. The protocol also includes guidelines for tissue sampling, fixation, and transport for downstream laboratory analyses such as histopathology and microbiology. Protocol refinement revealed practical considerations not previously described for this species, including variability in hepatic size and the absence of coelomic fat bodies in examined specimens, which simplified visceral exposure and influenced dissection strategy. These findings highlight the need to adapt necropsy techniques to species‐specific anatomical characteristics. This protocol provides a practical reference for veterinarians, pathologists, and researchers working with A. mexicanum , facilitating standardized postmortem examinations and improving the reliability and reproducibility of diagnostic and research findings in this important amphibian model. © 2026 Wiley Periodicals LLC. Basic Protocol 1 : External examination Basic Protocol 2 : Organs of the head and spinal cord examination Basic Protocol 3 : Organs of the coelomic cavity examination Support Protocol : Collection, preservation and transport of specimens for laboratory analysis

Music has been recognized as an artistic and therapeutic stimulus in humans and other animals. In rodents, most auditory enrichment studies have relied on human-composed music within the human auditory range, overlooking species-specific acoustic perception. Mice communicate mainly in the ultrasonic range (>20 kHz), particularly during courtship, producing structured songs with complex syllables and phrases. To address this gap, we developed and tested a digital ultrasonic music program inspired by murine courtship songs using vocalizations from BALB/c and C57BL/6 strains. Songs were recorded, behaviorally contextualized, and digitally adapted into structured ultrasonic stimuli. Enrichment did not induce anxiogenic effects. In BALB/c mice, ethograms and plus-maze testing revealed increased exploratory behavior in stimulated groups, while C57BL/6 mice showed more variable responses. No adverse effects were observed. This study provides a systematic approach to species-tailored ultrasonic music, generating both behavioral insights and a bioacoustic library that may support replicable protocols in animal enrichment, neuroscience, and welfare research.

El videojuego Porcípolis fue examinado como herramienta didáctica basada en TIC para sensibilizar a estudiantes de los primeros semestres de Medicina Veterinaria (MV) y Medicina Veterinaria y Zootecnia (MVZ) sobre Bienestar Animal (BA). Mediante un diseño cuasiexperimental, se analizaron los cambios en empatía, compasión y conocimientos sobre bienestar animal. Los participantes fueron asignados a un grupo control (sin exposición al videojuego) y a un grupo experimental (expuestos al videojuego). La recolección de datos se realizó mediante un pretest y un postest, utilizando cuestionarios con escalas tipo Likert y preguntas abiertas para evaluar la experiencia de usuario, la empatía, la compasión hacia los animales y los conocimientos sobre bienestar animal. Se calcularon puntajes totales para los cuestionarios y se analizaron los datos mediante comparaciones estadísticas. Los resultados revelaron valoraciones positivas de la experiencia de usuario (UX), especialmente en las dimensiones de usabilidad y experiencia de aprendizaje, lo que evidencia el potencial pedagógico del videojuego. Sin embargo, se identificó la necesidad de fortalecer el proceso educativo mediante estrategias de retroalimentación acompañadas por el docente. Porcípolis se perfila como un recurso didáctico eficaz para la enseñanza del bienestar animal, cuya efectividad puede ampliarse a través de entornos educativos que fomenten la reflexión crítica sobre las decisiones tomadas en el entorno virtual.

Background: mast cell tumor (MCT) is one of the most common neoplasms in canines, and histological grading is crucial for its prognosis. However, there is limited local information on the influence of factors such as sex, age, breed, and anatomical location of the lesion on the malignancy grade of this neoplasm. These factors are important for risk assessment and understanding the biological behavior of the tumor. Objective: to assess the association between risk factors (sex, age, breed, anatomical location) and histological grade of MCTs diagnosed at the Animal Pathology Laboratory of the Universidad de Antioquia between 2019 and 2023. Methods: retrospective study based on histopathology reports of canine biopsies; filtering patients diagnosed with MCT. Data on year of report, dog, and tumor characteristics were extracted. Descriptive statistics were presented as relative frequencies, 95% confidence intervals (CI), and Z-tests and Chi-square tests were used to identify differences between proportions. Results: 409 cases of canine MCT were analyzed, of which 74.8% were low grade (LG) and 25.2% high grade (HG). Females presented a higher frequency of high grade MCT (HG-MCT) (50.5%), with no significant differences by sex (p>0.05). Patients aged 5 to 8 years showed greater predisposition to low grade MCT (LG-MCT), while those aged 9 to 16 years to HG-MCT (p<0.05). The Bulldog and French Bulldog breeds had a greater predisposition to HG-MCT (p0.05). Conclusions: the findings highlight the relevance of age and breed in the diagnosis and management of MCT. Dogs of certain breeds and ages may be more likely to be susceptible to more aggressive forms of the tumor, which is relevant for clinical management and early risk identification.

Intensification of swine production can predispose pigs to chronic stress, with adverse effects on the neuroendocrine and immune systems that can lead to health problems, poor welfare, and reduced production performance. Consequently, there is an interest in developing tools to prevent or eliminate chronic stress. Music is widely used as a therapeutic strategy for stress management in humans and may have similar benefits in non-human animals. This study evaluated the effects of a music-based auditory enrichment program in pigs from a multidimensional perspective by assessing psychophysiological responses. Two experimental groups of 20 pigs each were selected for the study: one enriched, exposed to a program of functional veterinary music designed for pigs, and a control group without auditory stimulation. Qualitative behavior assessment (QBA) and skin lesions indicative of agonistic behavior were used to evaluate the psychological determinants underlying the observed behaviors. Physiological assessment included hemograms, with the determination of the neutrophil:lymphocyte ratio and daily measurements of cortisol and salivary alpha-amylase levels. The results demonstrated a positive effect of a music-based auditory program on psychophysiological responses. Therefore, this strategy developed for environmental enrichment may be beneficial in reducing stress and contributing to the welfare and health of pigs under production conditions.

The effects of sound stimulation as a sensorial environmental enrichment for captive animals have been studied. When appropriately implemented for farm animals, it can improve welfare, health, and productivity. Furthermore, there are indications that music can induce positive emotions in non-human animals, similar to humans. Emotion is a functional state of the organism involving both physiological processes, mediated by neuroendocrine regulation, and changes in behavior, affecting various aspects, including contextual perception and welfare. As there is very limited information on non-human animals, the objective of this review is to highlight what is known about these processes from human biological and comparative perspectives and stimulate future research on using music to improve animal welfare.

Music is a complex stimulus, with various spectro-temporal acoustic elements determining one of the most important attributes of music, the ability to elicit emotions. Effects of various musical acoustic elements on emotions in non-human animals have not been studied with an integrated approach. However, this knowledge is important to design music to provide environmental enrichment for non-human species. Thirty-nine instrumental musical pieces were composed and used to determine effects of various acoustic parameters on emotional responses in farm pigs. Video recordings (n = 50) of pigs in the nursery phase (7–9 week old) were gathered and emotional responses induced by stimuli were evaluated with Qualitative Behavioral Assessment (QBA). Non-parametric statistical models (Generalized Additive Models, Decision Trees, Random Forests, and XGBoost) were applied and compared to evaluate relationships between acoustic parameters and pigs’ observed emotional responses. We concluded that musical structure affected emotional responses of pigs. The valence of modulated emotions depended on integrated and simultaneous interactions of various spectral and temporal structural components of music that can be readily modified. This new knowledge supports design of musical stimuli to be used as environmental enrichment for non-human animals.

There is a lack of clarity on whether pigs can emotionally respond to musical stimulation and whether that response is related to music structure. Qualitative Behavioral Assessment (QBA) was used to evaluate effects of 16 distinct musical pieces (in terms of harmonic structure) on emotional responses in nursery pigs (n = 30) during four periods: “habituation”, “treatments”, “breaks” and “final”. Data were evaluated using Principal component analysis (PCA). Two principal components (PC) were considered in the analysis: PC1, characterized as a positive emotions index, included the emotional responses content, playful, sociable, and happy, whereas PC2, characterized as a negative emotions index, included fearful, inquisitive, and uneasy with positive loadings, and relaxed and calm with negative loadings. Musical stimulation (treatment) increased (P < 0.01) both emotional indices, compared to other periods and this response was influenced by harmonic characteristics of the music. We concluded that pigs have a wide variety of emotional responses, with different affective states related to the music structure used, providing evidence of its potential use as environmental enrichment for this species.

There is a lack of clarity on whether pigs can emotionally respond to musical stimulation and whether that response is related to music types. Qualitative Behavioral Assessment (QBA) was used to evaluate effects of 16 distinct musical pieces (in terms of harmony and vertical density) on emotional responses in nursery pigs (n=30) during four periods: “habituation,” “treatments,” “breaks,” and “final.” Data were evaluated using Principal component analysis (PCA). Two principal components (PC) were considered in the analysis: PC1, characterized as a positive emotions index, included the terms content, playful, sociable, and happy, whereas PC2, characterized as a negative emotions index, included fearful, inquisitive, and uneasy with positive loadings, and relaxed and calm with negative loadings. Musical stimulation (treatment) increased (P < 0.01) both emotional indices, compared to other periods and this response was influenced by the compositional characteristics of the music. We concluded that pigs have a wide variety of emotional responses, with different affective states related to the type of music used, providing evidence of its potential use as environmental enrichment for the species.

Background: Hydrogen peroxide (H₂O₂) is a key reactive oxygen species (ROS) generated during appendage regeneration among vertebrates. However, its role during tail regeneration in axolotl as redox signaling molecule is unclear.Results: Treatment with exogenous H₂O₂rescues inhibitory effects of apocynin‐induced growth suppression in tail blastema cells leading to cell proliferation. H₂O₂also promotes recruitment of immune cells, regulate the activation of AKT kinase andAgr2expression during blastema formation. Additionally, ROS/H₂O₂regulates the expression and transcriptional activity of Yap1 and its target genesCtgfandAreg.Conclusions: These results show that H₂O₂is necessary and sufficient to promote tail regeneration in axolotls. Additionally, Akt signaling andAgr2were identified as ROS targets, suggesting that ROS/H₂O₂is likely to regulate epimorphic regeneration through these signaling pathways. In addition, ROS/H₂O₂‐dependent‐Yap1 activity is required during tail regeneration.