Minimising pain in farm animals: the 3S approach - 'Suppress, Substitute, Soothe'

Assessment of Pain and Inflammation in Domestic Animals Using Infrared Thermography: A Narrative Review

Pain assessment in domestic animals has gained importance in recent years due to the recognition of the physiological, behavioral, and endocrine consequences of acute pain on animal production, welfare, and animal model validity. Current approaches to identifying acute pain mainly rely on behavioral-based scales, quantifying pain-related biomarkers, and the use of devices monitoring sympathetic activity. Infrared thermography is an alternative that could be used to correlate the changes in the superficial temperature with other tools and thus be an additional or alternate acute pain assessment marker. Moreover, its non-invasiveness and the objective nature of its readout make it potentially very valuable. However, at the current time, it is not in widespread use as an assessment strategy. The present review discusses scientific evidence for infrared thermography as a tool to evaluate pain, limiting its use to monitor acute pain in pathological processes and invasive procedures, as well as its use for perioperative monitoring in domestic animals.

A Brief Update on the Challenges and Prospects for Goat Production in Mexico

In Mexico, information on goat production is scarce and documenting goat production challenges and future perspectives could be of great value, not only for Latin America, but also for international players—including those from farms, industry, and academia. Therefore, the objective of this review is to provide current knowledge on goat production systems in Mexico and discuss current challenges and future perspectives for this animal production sector. In Mexico, more than 70% of goats are produced under extensive production systems in arid and semi-arid areas and roughly 25% are produced in intensive or semi-intensive systems. Main breeds are French Alpine, Saanen, Toggenburg, LaMancha, Nubian, Boer, and their crosses. The main challenges are correlated at different levels, where economic, social, and environmental issues are mixed and are closely associated with goat health and welfare. Newly available farming technologies could be an option that should be explored. Mexican goat farming systems will need to look at the animal, social, and environmental factors to promote sustainable production systems.

Meloxicam administration in the management of postoperative pain and inflammation associated with caesarean section in beef heifers: Evaluation of reproductive parameters

Post-operative pain and inflammation are normal physiological reactions to caesarean section. Their management in cattle have rarely been investigated. This surgical procedure negatively affects reproductive function with, for example, a reduction in fertility resulting in an increase in calving interval. In this multicenter clinical trial, the objective was to evaluate the impact on reproductive performance of meloxicam injected before caesarean section to manage post-operative pain and inflammation. Meloxicam is a non-steroidal anti-inflammatory drug. One hundred and twenty-seven Charolais heifers (n = 127) were recruited from 47 farms in six French veterinary practices in the Burgundy region. The heifers underwent a non-elective standardized caesarean section operation. Heifers were randomly assigned to one of two groups: meloxicam (n = 66), intravenous meloxicam injection before surgery, or control (n = 61). Reproductive performance and health information were recorded from the time of the caesarean section to the next calving or to culling. In our study, meloxicam administration before caesarean section had no effect on the incidence of retained placenta (18.2% of treated vs 25.0% of control cows, p = 0.35). The pregnancy rate was higher in treated than in control cows (83.1% vs 67.8%, p = 0.04 after multivariate analysis) and a survival analysis showed that the median calving interval was 35 days shorter in the meloxicam (t_50% = 417 days) compared to the control group (t_50% = 452 days, p = 0.05). A trend was also observed for culling rate to be lower in treated (4.7%) compared to control cows (13.3%, p = 0.09). In conclusion, this study suggests that there is a beneficial effect of meloxicam administration before caesarean section on reproductive performance in Charolais heifers.

Surgical Castration Changes Struggle Behavior and Vocalizations in Male Piglets

This study assessed acute pain in piglets during castration through behavioral indicators. Piglets (n=88) were randomly allocated to one of two treatments: surgical castration and sham-castration. Within 24 hours after birth, identical castration procedures were followed for both treatment groups, except sham piglets were not castrated. Struggle behavior (curl ups, leg kicks, and body flailing) and vocalization (duration and peak frequency) were analyzed during the castration procedure. Castrated piglets kicked more frequently than sham piglets (28.8 vs. 21.3 kicks/min, SE = 0.09; P = 0.02). Additionally, 51.2% of castrated piglets displayed body flailing, whereas only 4.4% of sham piglets displayed the same behavior (P = 0.03). Castrated piglets responded with more high frequency (≥1,000 Hz) calls than sham piglets (23.6 vs. 18.6 calls/min, SE = 0.26; P = 0.04) and high frequency calls tended to be of longer duration for castrated piglets (0.45 vs. 0.27 sec/call, SE = 0.04; P = 0.08). Results indicate that surgical castration increased the frequency of leg kicks, body flailing, and high frequency calls compared to sham-castration, suggesting these may be useful behavioral indicators of acute pain in piglets.

The Welfare of Beef Cattle in the Scientific Literature From 1990 to 2019: A Text Mining Approach

Beef cattle are the third most numerous terrestrial farmed animals worldwide. Factors such as geographical region, animal category, breed, and rearing system pose specific animal welfare challenges that can have an impact on animal and public health. This article uses text mining (TM) and topic analysis (TA) to explore the scientific literature on beef cattle welfare published in English from 1990 to 2019. Our aim was to reveal the main research topics and their evolution over time. Our analysis showed that the three most relevant themes in research since 1990 have to do with calf behaviour and management, efficiency, and environmental sustainability, and the effects of transport and slaughter on meat quality. Topics showing the most marked increase in the number of papers published deal with stakeholders' perceptions and market opportunities for added-value beef products and risk factors for morbidity and mortality, especially in relation to calf health, antimicrobial use, and antimicrobial resistance. The results indicate a particular focus on the welfare of calves, especially in the veal industry. Pain relief during the castration of calves and bulls also featured prominently. Research is also increasingly assessing aspects of beef cattle welfare that are interlinked to meat quality, the social and environmental sustainability of the sector in relation to market opportunities, and public health. The identified topics represent a basic source of information that can be used for further and more detailed analyses (e.g., systematic reviews) focussed on specific research themes or geographical areas.

Grimace Scores: Tools to Support the Identification of Pain in Mammals Used in Research

The 3Rs, Replacement, Reduction and Refinement, is a framework to ensure the ethical and justified use of animals in research. The implementation of refinements is required to alleviate and minimise the pain and suffering of animals in research. Public acceptability of animal use in research is contingent on satisfying ethical and legal obligations to provide pain relief along with humane endpoints. To fulfil this obligation, staff, researchers, veterinarians, and technicians must rapidly, accurately, efficiently and consistently identify, assess and act on signs of pain. This ability is paramount to uphold animal welfare, prevent undue suffering and mitigate possible negative impacts on research. Identification of pain may be based on indicators such as physiological, behavioural, or physical ones. Each has been used to develop different pain scoring systems with potential benefits and limitations in identifying and assessing pain. Grimace scores are a promising adjunctive behavioural technique in some mammalian species to identify and assess pain in research animals. The use of this method can be beneficial to animal welfare and research outcomes by identifying animals that may require alleviation of pain or humane intervention. This paper highlights the benefits, caveats, and potential applications of grimace scales.

Refinement of a colostrum-deprived pig model for infectious disease research

Well-defined pig models are useful to study the pathogenicity of newly recognized pathogens or strains in pigs and serve as animal models for some human diseases. The conventional pig model, where research pigs are sourced from commercial high-health production systems, is commonly used due to the easiness of getting pigs in a timely manner. However, freedom of the pig for the pathogen of interest is important at study start and serological assays to screen pigs for antibodies against newly identified pathogens or molecular assays detecting all possible circulating pathogen variants may not yet exist. Using colostrum-deprived (CD) pigs is a good alternative strategy to circumvent passively-acquired immunity against the pathogen of interest or exposure to pathogens shortly after birth. However, CD pigs are difficult to rear as they are highly susceptible to infections, and mortality rates in the first few days of life are often very high. Herein we report on refinement of a CD pig model with consistent survival rates of 90-100% of the piglets. •Step-by-step protocol to derive and rear CD piglets with higher expected survival rates.•Pig housing improvement minimizes the risk of disease transmission.•Infectious virus disease research pig model purpose.

PK/PD modeling of flunixin meglumine in a kaolin-induced inflammation model in piglets

Flunixin is marketed in several countries for analgesia in adult swine but little is known about its efficacy in piglets. Thirty-two piglets (6-8 days old) were randomized to receive placebo saline (n = 11, group CONTROL) or flunixin meglumine intravenously at 2.2 (n = 11, group MEDIUM) or 4.4 (n = 10, group HIGH) mg/kg, 10 hr after subcutaneous injection of kaolin in the left metacarpal area. A hand-held algometer was used to determine each piglet's mechanical nociceptive threshold (MNT) from both front feet up to 50 hr after treatment (cut-off value of 24.5 newton). Serial venous blood samples were obtained to quantify flunixin in plasma using LC-MS/MS. A PKPD model describing the effect of flunixin on the mechanical nociceptive threshold was obtained based on an inhibitory indirect response model. A two-compartmental PK model was used. A significant effect of flunixin was observed for both doses compared to control group, with 4.4 mg/kg showing the most relevant (6-10 newton) and long-lasting effect (34 hr). The median IC50 was 6.78 and 2.63 mg/ml in groups MEDIUM and HIGH, respectively. The ED50 in this model was 6.6 mg/kg. Flunixin exhibited marked antinociceptive effect on kaolin-induced inflammatory hyperalgesia in piglets.

Chilean consumers’ perception about animal welfare in dairy production systems: short communication

Information on animal welfare and ways that farm animals are kept has gained more and more importance with regard to the consumers’ behaviour and expectations when buying food products. In certain countries, animal welfare is considered as an important extrinsic quality attribute of animal products. Until now, hardly any studies have been conducted in Latin America on consumers’ expectations and knowledge regarding animal welfare aspects of the products they buy. The objective of this study was to determine the knowledge and expectations of consumers in Chile regarding information about dairy production systems and animal welfare, and the main aspects they considered when buying dairy products. A face-to-face interview was conducted on a sample of 501 persons from the Province of Santiago, Chile. The survey was conducted in major supermarkets from 15 different municipalities of Santiago in November and December 2012. The main aspects considered before purchasing dairy products were fat content (30%) and price (26%). It was shown that 66.9% of the participants associated the term animal welfare with responsible pet ownership, 12.4% to farm animal care, 11.6% to vegetarianism and 9.2% to the freedom and nature of animals. Age, educational level and family income were related (P < 0.001) to responsible pet ownership whereas gender did not relate to the concept of animal welfare. From the total surveyed participants, 73% were interested in receiving more information about animal welfare; 62% of these were women between 18 and 30 years of age. Information about the conditions of milk production and animal welfare were considered to be an important aspect to be included in dairy products’ labelling for 86% of the participants. Also, 68% of the participants declared a willingness to pay more for an animal welfare friendly dairy product. Data from this study may be useful in order to include animal welfare as an extrinsic quality attribute of dairy products in Chile and to define a market-oriented strategy including animal welfare.

Evaluation of breeding strategies for polledness in dairy cattle using a newly developed simulation framework for quantitative and Mendelian traits

Background

Intensified selection of polled individuals has recently gained importance in predominantly horned dairy cattle breeds as an alternative to routine dehorning. The status quo of the current polled breeding pool of genetically-closely related artificial insemination sires with lower breeding values for performance traits raises questions regarding the effects of intensified selection based on this founder pool.

Methods

We developed a stochastic simulation framework that combines the stochastic simulation software QMSim and a self-designed R program named QUALsim that acts as an external extension. Two traits were simulated in a dairy cattle population for 25 generations: one quantitative (QMSim) and one qualitative trait with Mendelian inheritance (i.e. polledness, QUALsim). The assignment scheme for qualitative trait genotypes initiated realistic initial breeding situations regarding allele frequencies, true breeding values for the quantitative trait and genetic relatedness. Intensified selection for polled cattle was achieved using an approach that weights estimated breeding values in the animal best linear unbiased prediction model for the quantitative trait depending on genotypes or phenotypes for the polled trait with a user-defined weighting factor.

Results

Selection response for the polled trait was highest in the selection scheme based on genotypes. Selection based on phenotypes led to significantly lower allele frequencies for polled. The male selection path played a significantly greater role for a fast dissemination of polled alleles compared to female selection strategies. Fixation of the polled allele implies selection based on polled genotypes among males. In comparison to a base breeding scenario that does not take polledness into account, intensive selection for polled substantially reduced genetic gain for this quantitative trait after 25 generations. Reducing selection intensity for polled males while maintaining strong selection intensity among females, simultaneously decreased losses in genetic gain and achieved a final allele frequency of 0.93 for polled.

Conclusions

A fast transition to a completely polled population through intensified selection for polled was in contradiction to the preservation of high genetic gain for the quantitative trait. Selection on male polled genotypes with moderate weighting, and selection on female polled phenotypes with high weighting, could be a suitable compromise regarding all important breeding aspects.

Electronic supplementary material

The online version of this article (doi:10.1186/s12711-016-0228-7) contains supplementary material, which is available to authorized users.

Evaluating the efficacy of a topical anaesthetic formulation and ketoprofen, alone and in combination, on the pain sensitivity of dehorning wounds in Holstein-Friesian calves

The aim of this study was to investigate the effect of a topically applied local anaesthetic and the non-steroidal anti-inflammatory drug ketoprofen, alone and in combination, on the pain sensitivity response of calves to dehorning (mean age 2.2 months). Calves were randomly allocated and blocked by age to one of four groups. Groups were: scoop dehorning (D, n = 8), scoop dehorning + i.m. administration of 3 mg/kg ketoprofen (DK, n = 8), scoop dehorning + application of topical anaesthetic (DTA, n = 7) and scoop dehorning + application of topical anaesthetic and i.m. administration of ketoprofen (DKTA, n = 7). A pressure algometer was used to determine the mechanical nociceptive threshold (MNT), being the pressure (kg/f) at which calves withdrew from the stimulus. Measurements were taken before dehorning and at 1 min, 1, 2, 5 and 24 h post-dehorning at both the cut skin edge of the wound and the peri-wound area. The effect of treatment changed over time (P < 0.001). MNT was highest before treatment (MNT = 5.03 kg/f) and tended to decrease over time (MNT = 1.16 kg/f 24 h post-treatment). Overall, D calves exhibited the lowest MNT with an average of 1.77 kg/f. DTA calves had the highest MNT (3.89 kg/f), followed closely by DKTA calves (3.24 kg/f). DK calves exhibited an intermediate MNT of 2.61 kg/f. MNT of the cut skin edge was generally lower than that of the peri-wound area (2.01 vs 3.81 kg/f, respectively, P = 0.02).The topical anaesthetic formulation significantly reduced the pain sensitivity of dehorning wounds. There was no observed enhanced analgesic effect with addition of ketoprofen. The cut skin edge was more sensitive to pressure than the peri-wound area.

Can novel methods be useful for pain assessment of castrated piglets?

Given that surgical castration is a painful practice performed on millions of pigs every year, a need to identify novel reliable pain assessment tools exists in order to test anaesthetic and analgesic protocols that may reduce related pain. Two treatments were considered: handling (H) and surgical castration (C). Physiological (cortisol, lactate, glycaemia, rectal and eye temperature) and behavioural variables (latency to move after treatment and alterations in posture and walking) were analysed. Cortisol showed the greatest level in C piglets within 20 min after the surgical procedure and a positive correlation with glucose concentration. Eye temperature was higher in C piglets, and the same difference was detected for rectal temperature 3 h after castration. Behavioural parameters revealed that C piglets had longer latency to move and a higher percentage of them showed alterations in posture and walking. Results of this study showed that, in castrated piglets behavioural and physiological alterations occur mainly in the first 3 h from treatment. Latency to move, alterations in posture and walking, and eye temperature appear to give additional and useful information in piglet pain assessment. However, differently from the behavioural parameters considered, eye temperature involves several manipulations of the animals and a long process to acquire the data.

Welfare implications of invasive piglet husbandry procedures, methods of alleviation and alternatives: a review

Iron administration, teeth clipping, tail docking and castration are common invasive husbandry procedures performed on piglets on commercial farms, generally within the first week of life. These procedures are performed to prevent potential health and welfare problems of piglets and/or the sow, or, with respect to castration, to enhance meat quality. The objectives of this review were firstly, to provide the rationale and scientific evidence for performing these procedures, secondly, to describe the welfare implications of these procedures, and lastly, to describe mitigation strategies or alternatives that can be used to eliminate or reduce the pain caused by these procedures. Administering supplementary iron is necessary to prevent anaemia in piglets and the procedure has a low welfare impact. The stated benefits of teeth clipping to prevent udder lesions do not appear to outweigh the risk from injury and infection in piglets following the procedure. Tail docking reduces the prevalence of tail biting, but does not eliminate this behaviour and the practice of tail docking can cause acute pain. Castration is primarily performed to reduce the occurrence of boar taint, but alternatives are now available that negate the need to perform this procedure. Teeth clipping, tail docking and castration all cause behavioural and physiological changes indicative of acute pain and can have potentially long-term negative consequences such as causing abscesses, lesions and the formation of neuromas. Therefore effective pain mitigation strategies (e.g. analgesia, local or general anaesthesia) that markedly alleviate the pain caused by these procedures are necessary to improve the welfare of piglets. Alternatively, if management practices are available that eliminate the need for performing these procedures altogether, then they should be adopted.

Attitudes of farmers and veterinarians towards pain and the use of pain relief in pigs

A survey of UK-based pig farmers and veterinarians was conducted, in order to investigate attitudes to pain and the use of pain relief in pigs. Survey respondents were asked to indicate which anti-inflammatory drugs they used or prescribed for pigs, how often these were administered, and the level of pain they associated with particular conditions. The survey found that veterinarians used a range of anti-inflammatory products to treat pigs with lameness. While both farmers and veterinarians gave similar pain scores overall, farmers rated gastrointestinal disease as more painful and conversely veterinarians scored lameness higher. Female and younger respondents gave higher pain scores than males and older respondents. Overall, farmers and veterinarians had a positive attitude towards pain relief in pigs with the majority agreeing that animals recovered more promptly when pain relief was administered. Most farmers agreed that the recognition and management of pain is an important part of pig husbandry, and many expressed an interest in finding out more about identifying pain in this species as well as the treatment options available. The study highlighted potential barriers to the increased application of pain relief in pigs in that almost one-third of veterinarians and two-thirds of farmers did not agree that they discussed pain management with each other, while other respondents indicated that they found it difficult to recognise pain in pigs, and did not know how to treat it appropriately.

The impact of 3 strategies for incorporating polled genetics into a dairy cattle breeding program on the overall herd genetic merit

Dehorning in cattle has been associated with behavioral, physiological, and neuroendocrine responses indicative of pain. Unaddressed, the pain associated with a routine production procedure could contribute to a negative public perception of livestock production practices. Alternative considerations of dehorning include the selection of polled cattle within herds, thereby avoiding pain and production loss. As polledness results from an autosomal dominant pattern of inheritance, genetic selection for polled cattle could reduce the prevalence of the horned trait. Herein we discuss 3 strategies to incorporate polled genetics into a cow herd and the estimated impact on the overall genetic merit of the herd. Furthermore, the availability and genetic merit of polled artificial insemination bulls in the United States is summarized. Both Holstein and Jersey dairy bulls registered with the National Association of Animal Breeders from December 2010 through April 2013 were queried. Polled bulls were identified as either being homozygous (PP) or heterozygous (Pp) and the average net merit (NM) predicted transmitting ability (PTA) of each sire group was calculated. The percentage of polled calves born each year over a 10-yr period was calculated for the following 3 scenarios: (A) various percentages of horned cows were randomly mated to Pp bulls, (B) various percentages of horned cows were preferentially mated to Pp bulls, and (C) horned cows were selectively mated to PP bulls, heterozygous cows to Pp bulls, and homozygous polled cows to horned bulls. Additionally, the change in NM PTA of the cow herd was calculated over the same period. The highest percentage of polled animals (87%) was achieved in scenario C. An evaluation of the herd NM PTA highlights the trade-offs associated with increasing polled genetics. Given the current genetic merit of horned and polled bulls, increasing the percentage of polled calves will decrease the NM PTA in Holstein, but may have minimal impact in Jersey herds. Decisions regarding selective breeding to increase polled genetics will need to be evaluated in the context of production objectives, cost of dehorning, and impact on overall genetic merit.

Pain assessment in animal models: do we need further studies?

In the last two decades, animal models have become important tools in understanding and treating pain, and in predicting analgesic efficacy. Although rodent models retain a dominant role in the study of pain mechanisms, large animal models may predict human biology and pharmacology in certain pain conditions more accurately. Taking into consideration the anatomical and physiological characteristics common to man and pigs (median body size, digestive apparatus, number, size, distribution and communication of vessels in dermal skin, epidermal-dermal junctions, the immunoreactivity of peptide nerve fibers, distribution of nociceptive and non-nociceptive fiber classes, and changes in axonal excitability), swines seem to provide the most suitable animal model for pain assessment. Locomotor function, clinical signs, and measurements (respiratory rate, heart rate, blood pressure, temperature, electromyography), behavior (bright/quiet, alert, responsive, depressed, unresponsive), plasma concentration of substance P and cortisol, vocalization, lameness, and axon reflex vasodilatation by laser Doppler imaging have been used to assess pain, but none of these evaluations have proved entirely satisfactory. It is necessary to identify new methods for evaluating pain in large animals (particularly pigs), because of their similarities to humans. This could lead to improved assessment of pain and improved analgesic treatment for both humans and laboratory animals.

Pain behaviour after castration of piglets; effect of pain relief with lidocaine and/or meloxicam

Behavioural responses and the effect of lidocaine and meloxicam on behaviour of piglets after castration were studied. A total of 144 piglets of 2 to 5 days of age were allocated to one of six treatments: castration (CAST), castration with lidocaine (LIDO), castration with meloxicam (MELO), castration with lidocaine and meloxicam (L + M), handling (SHAM) and no handling (NONE). Behaviour was observed for 5 days after the procedure, growth until weaning was recorded and characteristics of the castration wound noted. MELO piglets showed significantly (P < 0.05) more no pain-related behaviour than CAST and LIDO at the afternoon after castration, and were not significantly different from SHAM and NONE. LIDO piglets showed an increase (P < 0.001) in tail wagging, lasting for 3 days. This increase was not seen in L + M piglets. The occurrence of several behaviours changed with age, independent of treatment. A treatment effect on growth was not found. Wound healing was rapid in all treatments, but thickening of the heal was observed in several piglets, suggesting perturbation in the cicatrization process. Our study showed a pain-relieving effect of meloxicam after castration. Local anaesthesia resulted in piglets performing more tail wagging during the first few days after castration, which was prevented by administering meloxicam in combination with local anaesthesia.