Unmitigated Surgical Castration in Calves of Different Ages: Electroencephalographic and Neurohormonal Findings

Pain pathophysiology and pharmacology of cattle: how improved understanding can enhance pain prevention, mitigation, and welfare

Globally, humans rely on cattle for food production; however, there is rising societal concern surrounding the welfare of farm animals. From a young age, cattle raised for dairy and beef production experience pain caused by routine management procedures and common disease conditions. The fundamental mechanisms, nociceptive pathways, and central nervous system structures required for pain perception are highly conserved among mammalian species. However, there are limitations to a comparative approach to pain assessment due to interspecies differences in the expression of pain. The stoicism of prey species may impede pain identification and lead to the assumption that cattle lack pain sensitivity. This highlights the importance of establishing validated bovine-specific indicators of pain-a prerequisite for evidence-based pain assessment and mitigation. Our first objective is to provide an overview of pain pathophysiology to illustrate the importance of targeted analgesia in livestock medicine and the negative welfare outcomes associated with unmitigated pain. This is followed by a review of available analgesics, the regulations governing their use, and barriers to implementation of on-farm pain management. We then investigate the current research undertaken to evaluate the pain response in cattle-a critical aspect of the drug approval process. With an emphasis on emerging research in animal cognition and pain pathology, we conclude by discussing the significant influence that pain has on cattle welfare and areas where further research and modified practices are indicated.

Repertoire of timescales in uni - and transmodal regions mediate working memory capacity

Working memory (WM) describes the dynamic process of maintenance and manipulation of information over a certain time delay. Neuronally, WM recruits a distributed network of cortical regions like the visual and dorsolateral prefrontal cortex as well as the subcortical hippocampus. How the input dynamics and subsequent neural dynamics impact WM remains unclear though. To answer this question, we combined the analysis of behavioral WM capacity with measuring neural dynamics through task-related power spectrum changes, e.g., median frequency (MF) in functional magnetic resonance imaging (fMRI). We show that the processing of the input dynamics, e.g., the task structure's specific timescale, leads to changes in the unimodal visual cortex's corresponding timescale which also relates to working memory capacity. While the more transmodal hippocampus relates to working memory capacity through its balance across multiple timescales or frequencies. In conclusion, we here show the relevance of both input dynamics and different neural timescales for WM capacity in uni - and transmodal regions like visual cortex and hippocampus for the subject's WM performance.

A nationwide survey on producer and veterinarian perceptions of the painfulness of procedures and disease states in dairy and beef cattle

Failure to adequately manage pain in cattle causes suffering and is thus a welfare concern for the livestock industry. The objectives of this study were to summarize caregiver perceptions of the painfulness of various procedures and disease conditions in cattle. This survey also assessed factors that impact the perception of painfulness and determined relationships between pain perception and mitigation in producers and veterinarians in the United States beef and dairy cattle industries. An online survey was distributed via organization listservs and social media groups representing beef and dairy veterinarians and producers. The survey included questions about respondent demographics and pain perception and frequency of pain mitigation use for a variety of common husbandry procedures and disease conditions in cattle less than 2 months, 2-12 months, and greater than 12 months of age. Descriptive statistics were generated, and ordinal logistic regressions were used to assess the relationship between perceived pain level, frequency of pain mitigation use, and respondent demographic factors (e.g., gender, age, and role). There was a relatively low percentage of respondents that identified there was "no pain" associated with the listed procedures and conditions. Across the majority of procedures and conditions and cattle age categories, men perceived procedures to be less painful than women (P < 0.05). Veterinarians and producer-veterinarians perceived procedures to be more painful than producers (P < 0.05) for the majority of procedures and conditions. There were some differences identified between respondent age groups in pain perception but the trends were not consistent across procedures and conditions. There was a significant positive linear trend, with greater perceived pain associated with greater likelihood of providing local and systemic analgesia for all procedures and conditions across all cattle age categories (P ≤ 0.02). Perception of pain is complex and multifactorial, and it influences the likelihood to treat pain in cattle. This research highlighted the importance of understanding how these factors may play a role in increasing the use of pain mitigation within the beef and dairy industries.

Substance P concentrations in the blood plasma and serum of adult cattle and calves during different painful procedures and conditions - a systematic review

Background

Pain in cattle is a major welfare problem, as cattle mask their pain. Subjective and objective parameters to assess pain in cattle have been described. Among the objective parameters to evaluate pain in cattle is substance P (SP). SP is a neurotransmitter, which is involved in the processing of noxious information to the brain; it seems to be a more objective indicator for nociception than cortisol, which has long been used as a biomarker for pain and stress in cattle. The objective of this systematic review was to assess the existing literature about SP during painful procedures, conditions, and diseases in cattle in form of a systematic review.

Results

Following the PRISMA statement, 36 out of 236 studies were included in this systematic review. Study design, grouping, age and weight of animals, processing of blood samples for the assessment of SP, and results were heterogenous. The largest number of studies originated from the United States of America and Canada and were published in 2018. A higher number of studies were done on calves (69.4%, n = 25) compared with adult cattle (30.6%, n = 11). Most studies were done to assess SP concentrations after administration of analgesics prior to husbandry procedures in calves.

Conclusions

There is a manageable number of studies assessing SP concentrations during painful procedures, conditions, and diseases in cattle. SP seems to be a suitable biomarker for nociception in cattle, but results of research work are heterogenous, and SP concentrations of calves and adult cattle differ throughout studies. Basic research work is missing and is needed to assess factors others than nociception which might influence the SP concentrations in the blood plasma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03304-6.

Unmitigated Surgical Castration in Calves of Different Ages: Cortisol Concentrations, Heart Rate Variability, and Infrared Thermography Findings

Simple Summary

In the United States, castration is a common husbandry procedure utilized in the cattle industry. Despite castration being painful, it is commonly performed without the use of analgesia, one reason being the lack of available approved analgesics in the United States for use in alleviating pain associated with castration in cattle. Additionally, if pain mitigation is used, it is more often provided to older animals as there is a notion that younger animals experience pain to a lesser degree than older ones. The aim of this study was to characterize physiological responses to unmitigated surgical castration in calves of varying ages in terms of cortisol concentration, heart rate variability, and changes in eye temperature. Overall, our results indicate that the measured physiological responses to castration differed between age groups and changed over time post-castration. Younger calves showed a different response pattern than older calves for many of the variables measured suggesting that the response to castration-induced pain may be age-specific. For example, the youngest calves had lower cortisol and average eye temperature as compared to the oldest calves. Additionally, many variables showed a differential response to castration-induced pain, as compared with simulated castration, thus suggesting physiological indicators that could be targeted in future development and validation of analgesics for alleviation of pain associated with castration in cattle.

Abstract

The objective was to characterize physiological responses to unmitigated surgical castration in calves of varying ages. Thirty male Holstein calves of three ages [<6 w (6W); 3 m (3M); 6 m (6M); n = 10] underwent a simulated castration treatment (SHAM) followed 24 h later by castration (CAST). For both treatments, heart rate variability, eye temperature, and cortisol were measured over time from treatment to specified end points to capture the acute response period. Interactions between treatment and age (p = 0.035) and time and age (p < 0.001) were noted for cortisol. The 6W calves had lower cortisol compared to 6M calves at SHAM and CAST. Cortisol of 6W calves decreased from peak to pre-treatment levels faster than 6M calves. An interaction between time and age was reported in squared differences of inter-beat-intervals (RMSSD; p = 0.02) and high-frequency power (HFP; p = 0.05), whereby both responses decreased in 6W calves during the sampling period which was not seen in 3M and 6M calves. Average eye temperature (AET) differed by age (p = 0.0018) whereby 6W calves had lower AET than 6M calves (p = 0.0013) regardless of treatment and time. The findings suggest that responses to unmitigated surgical castration seem to be mediated by the autonomic nervous system in an age-related manner.