Welfare Effects of the Use of a Combination of Local Anesthesia and NSAID for Disbudding Analgesia in Dairy Calves-Reviewed Across Different Welfare Concerns

Effects of meloxicam on the welfare of Holstein calves from 6 weeks to 6 months old undergoing amputation dehorning

Amputation dehorning (AD) is a common practice performed on calves, causing harmful effects such as pain, distress, anxiety, and fear. These effects extend to behavioral, physiological, and hematological responses, prompting serious ethical concerns regarding animal welfare, even when performed with local anesthesia. Meloxicam, a nonsteroidal anti-inflammatory drug, has been widely used to mitigate the side effects of dehorning and disbudding in calves. However, there is a notable gap in research regarding the effects of meloxicam on calves aged 6 wk to 6 mo undergoing AD procedures. This study was designed to assess the effectiveness of co-administering meloxicam with lidocaine, a cornual nerve anesthetic, in alleviating the adverse effects caused by the AD procedure in calves within this age range, compared with the use of lidocaine alone. Thirty Holstein calves were enrolled and randomly divided into 2 groups. The first group received a subcutaneous injection of 5 mL of lidocaine in the horn area and a subcutaneous injection of 0.9% saline at a dose of 0.025 mL/kg in the neck, administered 10 min before the AD procedure. The second group received a combination of lidocaine and meloxicam: a subcutaneous injection of 5 mL of lidocaine in the horn area and a subcutaneous injection of 20 mg/mL meloxicam at a dose of 0.025 mL/kg in the neck, also administered 10 min before the AD procedure. To avoid subjective bias, the researchers were blinded to the treatment groups. Pain-related behaviors, including tail flicking, head shaking, ear flicking, head rubbing, head crossing bar, and kicking, were observed, and physiological parameters, including heart rate, rectal temperature, respiration rate, mechanical nociceptive threshold (MNT), daily active steps, and food intake were monitored. Hematological conditions were determined using enzyme-linked immunosorbent assays and routine blood tests. The data were processed using a generalized linear mixed model. The outcomes demonstrated that the AD procedure increased the frequencies of ear flicking and resulted in rises in the respiration rate, heart rate, rectal temperature, and daily active steps. It also led to decreases in total food intake, forage intake, hay intake, MNT, and increased concentrations of prostaglandin E2 (PgE2), IL-1β, tumor necrosis factor-α (TNF-α), nitric oxide (NO), and malondialdehyde, as well as glutathione peroxidase activity. However, calves that received meloxicam treatment showed significant improvements in response to the AD procedure, including lower respiration rates, heart rates, and rectal temperatures; higher MNT; and lower intermediate cell ratio. They also had higher red blood counts, hemoglobin levels, hematocrit values; larger mean platelet volumes; and lower concentrations of PgE2, IL-1β, TNF-α, and NO. These results suggest that co-administration of lidocaine and meloxicam may aid in mitigating the adverse effects induced by the AD procedure on these calves, thereby supporting the use of meloxicam in conjunction with a local anesthetic in AD procedures for calves aged 6 wk to 6 mo.

Cold therapy and pain relief after hot-iron disbudding in dairy calves

Even when pain control is implemented, calves may experience pain for days after hot-iron disbudding. Whether calves seek pain relief post-disbudding offers a novel approach to assessing pain in these animals. By employing an approach-aversion paradigm, we explored the ability of cold therapy to provide immediate pain relief in disbudded calves. Calves were habituated to the manual placement of a cool or ambient pack on their forehead for a short duration simultaneous to milk reward consumption, prior to disbudding. Calves were then disbudded under local anaesthesia (procaine) and analgesia (meloxicam), and responses to the packs were observed over subsequent days. Individual calves were consistently exposed to either cool or ambient packs in different halves of a two-sided experimental pen, allowing for the testing of approach-aversion and conditioned place preference. We found calves approached milk rewards quicker and maintained contact for longer when receiving cold therapy compared to the ambient control. However, calves did not display any conditioned preference for the pen where they received the cool pack. These results add to the growing evidence of lasting pain following disbudding procedures and suggests that cold therapy provides some form of pain relief post-disbudding. Future studies should seek other ways to use cold therapy post-disbudding to reduce aversiveness and human involvement.

The effects of pain following disbudding on calf memory

Studies have found evidence of pain in the hours following hot-iron disbudding, but little is known about longer-lasting pain following this procedure. Work on humans and rats has shown that lasting pain can have negative effects on the formation and recall of memories. The objective of this study was to assess whether lasting pain following disbudding affects learning and memory in calves. A modified hole-board apparatus was used to assess how quickly calves were able to learn the locations of 4 bottles containing milk dispersed among 11 locations with empty bottles. At 14 d of age and after 6 d of training on this task, calves (n = 30) were randomly assigned to 3 treatments: disbudding with analgesic on the day of the procedure, disbudding with analgesic throughout the study, and sham disbudding. All calves were sedated, given a lidocaine cornual local block and a single injection of an nonsteroidal anti-inflammatory drugs. Starting on the day after their disbudding treatment, calves were tested daily using the modified hole-board apparatus. After 12 d of testing, the locations of the 4 milk-containing bottles were switched, and calves then relearned the locations of the rewarded bottles over the next 6 daily test sessions. We found general working memory (i.e., short-term memory) and reference memory (i.e., long-term memory) increased over the 12 d of testing, declined when locations were switched on d 13, and then again increased over the final 6 d of testing. We did not find an effect of treatment on any measure, perhaps because there was no lasting pain or because effects were too minor to detect using this test of spatial memory.

Behavioral changes in the first 3 weeks after disbudding in dairy calves

Hot-iron disbudding, the practice of cauterizing horn bud tissue to prevent horn growth in dairy calves, results in behavioral changes indicative of pain in the first few days after the procedure. However, few studies have quantified behavioral changes in the following weeks, while the burn wounds are still healing. Female Holstein calves were disbudded with a heated iron and pain relief (5.5 mL lidocaine cornual nerve block and 1 mg/kg oral meloxicam) at 4 to 10 d of age (n = 19) or not disbudded (n = 19). Calves wore ear tag accelerometers that reported the dominant behavior being performed at 1-min intervals from 3 to 21 d after disbudding. Compared with age-matched controls, disbudded calves tended to spend more time inactive throughout the observation period, ruminated less in the first 3 to 11 d after disbudding, and sucked more from a milk bottle beginning 5 d after disbudding until the end of the 21-d observation period. In addition to the accelerometer data, live observations of sleeping (using a behavioral proxy), lying, and ruminating were collected using instantaneous sampling at 5-min intervals for 24-h periods 3, 10, and 17 d after disbudding. Disbudded calves slept with their head down more on all live observation days and spent more time lying on the 17th d after disbudding, but ruminating did not differ compared with controls, in contrast to the accelerometer results. More time spent inactive, sleeping, and lying, and less time spent ruminating (as indicated by the accelerometer) can be interpreted as attempts to reduce painful stimulation of the disbudding wounds and allocate energy to healing. It is unclear whether the greater amount of sucking in the disbudded calves is nutritive (milk present) or non-nutritive (milk absent), as the algorithm did not distinguish the type of sucking, and further research is needed to explore the factors underlying this effect. We conclude that disbudding alters daily behavior patterns for at least 3 wk, far beyond the duration of recommended pain medication, raising additional welfare concerns about the procedure.

Calves peak-end memory of pain

In humans, the 'peak-end' rule states that recollection of an experience is most often influenced by the peak (the most intense moment) and end of the experience. We investigated whether calves followed the peak-end rule in their memory of a painful procedure: disbudding. As proxies for retrospective and 'real-time' reports of pain, we used conditioned place aversion, and reflex pain behaviours. In two separate trials, calves were subjected to two disbudding conditioning sessions (one horn per treatment), acting as their own control. In the first trial, calves (n = 22) were disbudded and remained in a pen for 4 h, and disbudded and left in another pen for 4 h with an additional 2 h following an analgesic treatment. In the second trial, calves (n = 22) were disbudded and left in pens for 6 h during both treatments, receiving the analgesic at either 2 h or 4 h after disbudding. Calves were then tested for place aversion. For both trials we did not observe a preference for the pens where calves received analgesic treatment towards the end of the session. We did not find an association between aversion and the sum, peak or end of pain behaviours. Results are not consistent with a peak-end effect in calves' memory of pain.

Histopathological findings in a pilot study of dairy calves disbudded with hot cauterization or caustic paste

We describe the histological tissue damage and compare the healing process in 16 dairy calves disbudded at a mean age of 6 days by cauterization or alkaline caustic paste application. Biopsies were taken 2 days (T2) and 2 weeks (T14) after disbudding from sedated calves treated with local anaesthetic and non-steroidal anti-inflammatory drugs. At T2, the cauterized horn buds generally had eosinophilic coagulative necrosis of the epidermis and superficial dermis, bordered basally by a neutrophilic demarcation zone. Lateral to the direct heat contact area, dermal blood vessels were thrombosed, with wall damage and perivascular neutrophils. In the caustic paste-treated horn buds, the epidermis and dermis had diffuse full-thickness liquefactive necrosis directly under the paste contact area. The necrosis spread laterally in the dermis beyond the area of paste contact and was bordered by a neutrophilic infiltrate. At T14, the cauterized horn buds had epidermal to superficial dermal ulceration and crusting, dermal neutrophilic infiltration and granulation tissue formation. In contrast, most of the caustic paste-treated horn buds consisted of a superficial dermal crust or predominantly necrotic tissue fragments. The remaining viable areas had histiocytic inflammation with peripheral neutrophils and early granulation tissue formation. Caustic paste disbudding caused poorly demarcated lesions that were more severe and extensive and took longer to heal than those due to cautery. Cauterization induced a more intense acute reaction adjacent to the primary lesion compared with caustic paste.

A Clinical Trial on the Welfare Effects of Administering Meloxicam to 10 to 21 Day Dairy Calves Following Caustic Paste Disbudding

Caustic paste disbudding (CPD) is widely utilized for calves, which has been known to result in adverse effects on the calves and ethical concerns related to animal welfare, despite the use of local anesthetics. The administration of meloxicam has been demonstrated to provide benefits in alleviating pain and inflammation in juvenile calves under 9 d old and subjected to CPD. Nonetheless, there is a scarcity of literature documenting the beneficial impact of meloxicam in alleviating pain in calves aged over 9 d that have undergone CPD. Therefore, the objective of this clinical trial was to evaluate the efficacy of administering meloxicam and lidocaine for cornual nerve block together in mitigating the deleterious effects of CPD, as opposed to using lidocaine alone in calves older than 9 d. Thirty Holstein calves, aged between 10 and 21 d, were enrolled and randomly assigned to 1 of 2 treatments: lidocaine alone (Placebo), lidocaine and normal saline treatment before CPD, and lidocaine plus meloxicam, lidocaine and 0.5 mg/kg of meloxicam treatment prior to CPD. The researchers were blind to the treatment of calves to control the subjective error. The occurrences of actions associated with pain, which included head shaking, head rubbing, ear flicking, tail flicking, kicking, and head passing through the fence, were recorded. Physiological performance, including the respiration rate, heart rate, rectal temperature, mechanical nociceptive threshold (MNT), food intake, and daily activity level, was monitored. Hematological conditions were ascertained through the use of routine blood tests and enzyme-linked immunosorbent assay. The generalized linear mixed model was employed to analyze the data. The research findings revealed that applying the CPD procedure significantly elevated the frequencies of tail flicking, head shaking, and kicking, resulted in increases in respiratory rate, heart rate, daily active steps, and food intake and a decrease in MNT, and led to alterations in hematological markers, including platelet counts, mean platelet volume, prostaglandin E2, constitutive nitric oxide synthase, and hydroxyl radical. Considerable benefits, such as lower heart rates, higher food intake, and MNTs, as well as lower levels of white blood cell counts, lymphocyte counts, hemoglobin, mean platelet volume, prostaglandin E2, tumor necrosis factor-α, constitutive nitric oxide synthase, malondialdehyde, and hydroxyl radical, were observed in the calves that received meloxicam treatment in response to CPD. The findings of the study indicate that the co-administration of lidocaine and meloxicam provides obvious benefits in mitigating pain, inflammation, and oxidative stress in calves aged over 9 d and undergoing CPD. This endorses the use of meloxicam during the disbudding and dehorning procedures of calves.

Indication of social buffering in disbudded calves

Most dairy calves are housed individually in early ontogeny but social housing has positive effects on calf welfare including an advantage of social buffering, i.e., when negative effects of stress are mitigated through social support of conspecific. The effects of social buffering has not yet been examined in relation to disbudding; a painful husbandry procedure commonly performed on young dairy calves. The objective of this study was to investigate the effect of pair versus individual housing on calves’ behavioral reaction to disbudding. In total 52 female calves were randomly allocated either to individual (n = 16) or pair housing (n = 36, 18 focal). Calves were hot-iron disbudded with a local anesthetic and their spontaneous behavior in home pens was recorded for 24 h pre- and post-disbudding. Eating forage, ruminating, resting, exploration, play, self-grooming, and pain-related behaviors were quantified during eight 20 min intervals during the 24 h periods pre- as well as post-disbudding. In pair-housed (PAIR) calves social resting, active and passive allo-grooming were additionally recorded. The differences between individually housed (INDI, n = 10) and PAIR calves (n = 12) were tested by general linear models. The changes in pre- and post-disbudding behaviors in all calves as well as in social behaviors of PAIR calves were tested by paired t-test. We found that head shaking (t =  − 3.46, P = 0.0024), head rubbing (t = 4.96, P < 0.0001) and self-grooming (t = 2.11, P = 0.04) increased in all calves after disbudding. Eating forage increased only in PAIR calves (t = 2.50, P = 0.030) which also resulted in a difference between treatments with PAIR calves fed more often than INDI calves (F_1,18 = 12.96, P = 0.002). Differences in eating forage may be an indication of improved ability of PAIR calves to recover from disbudding. No other significant differences were detected between treatment groups which might have been caused by our limited sample. Our results provide the first evidence that housing treatment affects calves’ reactions to disbudding, with possible indication of social buffering.

Graduate Student Literature Review: Role of pain mitigation on the welfare of dairy calves undergoing disbudding

This review synthesizes research findings on the pain and welfare of dairy calves undergoing disbudding procedures. We describe disbudding practices in North America as well as the use and perceptions of pain control for these procedures. Governing bodies across Canada and the United States, including each country's veterinary medical association and nationwide initiatives such as proAction and Farmers Assuring Responsible Management (FARM), recommend or require the use of a local anesthetic, a nonsteroidal anti-inflammatory drug (NSAID), and a sedative for disbudding procedures. Although the use of pain relief for disbudding has increased over the past decade or so, some in the dairy industry still do not believe that pain control for disbudding is necessary. As a painful procedure, disbudding has numerous welfare impacts on the calf both during and following the procedure that can be categorized under all 3 principles of animal welfare: natural living, biological functioning, and affective state. The use of pain control for disbudding; namely, a local anesthetic and NSAID, can improve welfare outcomes such as procedure-induced pain behavior, cortisol concentrations, mechanical nociceptive threshold, emotional states, and so on, compared with no pain control for the procedure. Although extensive research exists on pain control practices for disbudding, this review identified further gaps in knowledge and areas for future research. Mechanical nociceptive threshold can be evaluated around the disbudding wounds and is a reliable test in older calves; however, this outcome in very young calves after caustic paste disbudding has been reported to be inconclusive compared with that in older calves. As well, research evaluating xylazine sedation for disbudding has reported both potentially positive and negative results that are difficult to interpret or base suggestions on for the use of this drug. Finally, wounds caused by disbudding take a long time to heal (up to 13 wk) and have increased sensitivity for the entire healing process. Therefore, future research should aim to (1) determine accurate behavioral tests for calves under 1 wk of age undergoing disbudding to better understand their experience, (2) further attempt to understand the effects of xylazine sedation for disbudding and potential impacts of providing this medication, and (3) determine more ways to reduce the healing time and pain experienced by the calf after disbudding procedures.

Behavioral and Physiological Response to Routine Thermal Disbudding in Dairy Calves Treated with Transdermal Flunixin Meglumine

Transdermal flunixin meglumine was approved in 2018 to treat pain related to foot-rot in cattle, leading to the question of whether it would be effective as part of a comprehensive pain management strategy for disbudding. To investigate, calves were assigned to three treatment groups: 2% lidocaine cornual nerve block only (L), lidocaine nerve block +0.45 mg/lb (1 mg/kg) oral meloxicam (M), or lidocaine nerve block +1.5 mg/lb (3.3 mg/kg) transdermal flunixin meglumine (F) (n = 61). Ear flicking (p = 0.001), head shaking (p < 0.001), tail flicking (p < 0.001), interaction with the environment (p < 0.001), grooming (p < 0.01), posture changes (p < 0.05), and standing (p < 0.001) were impacted by the time relative to the procedure. Cortisol levels rose post procedure (p < 0.001). There was no difference in rates of behaviors or cortisol between treatments. These results indicate that calves showed alterations in behavior and cortisol in response to disbudding but not between treatments. We conclude that the pain management protocol for disbudding, which included transdermal flunixin meglumine with a lidocaine cornual nerve block, did not show significant differences from protocols using meloxicam with a lidocaine block, or a lidocaine block alone.

Early Life Painful Procedures: Long-Term Consequences and Implications for Farm Animal Welfare

Farm animals routinely undergo painful husbandry procedures early in life, including disbudding and castration in calves and goat kids, tail docking and castration in piglets and lambs, and beak trimming in chicks. In rodents, inflammatory events soon after birth, when physiological systems are developing and sensitive to perturbation, can profoundly alter phenotypic outcomes later in life. This review summarizes the current state of research on long-term phenotypic consequences of neonatal painful procedures in rodents and farm animals, and discusses the implications for farm animal welfare. Rodents exposed to early life inflammation show a hypo-/hyper-responsive profile to pain-, fear-, and anxiety-inducing stimuli, manifesting as an initial attenuation in responses that transitions into hyperresponsivity with increasing age or cumulative stress. Neonatal inflammation also predisposes rodents to cognitive, social, and reproductive deficits, and there is some evidence that adverse effects may be passed to offspring. The outcomes of neonatal inflammation are modulated by injury etiology, age at the time of injury and time of testing, sex, pain management, and rearing environment. Equivalent research examining long-term phenotypic consequences of early life painful procedures in farm animals is greatly lacking, despite obvious implications for welfare and performance. Improved understanding of how these procedures shape phenotypes will inform efforts to mitigate negative outcomes through reduction, replacement, and refinement of current practices.

Analgesic and cardiopulmonary effects of premedication with tramadol in calves anesthetized with the infusion of guaifenesin and thiamylal

This study examined the analgesic and cardiopulmonary effects of intravenous (IV) tramadol during general intravenous anesthesia in calves. Calves were premedicated with diazepam (0.2 mg/kg, IV) with tramadol (2 mg/kg, IV) (group T) or saline (group S). Anesthesia was induced by thiamylal sodium (4 mg/kg, IV) and maintained with an infusion (2 ml/kg/hr) of 5% guaifenesin containing thiamylal sodium (2 mg/ml). Additional thiamylal sodium (1~2 mg/kg, IV) was administered when interference from the calves was observed during surgery. The total counts of additional thiamylal sodium administration, analgesia score using a visual analog scale, recovery time, and cardiopulmonary function in the different groups were assessed and compared. Group T showed significantly fewer counts of additional drug administration and a significantly higher analgesia score. Tramadol may provide adequate analgesia with minimal cardiopulmonary changes in calves during general anesthesia.

Dairy calves show behavioural responses to hot iron disbudding after local anaesthesia with procaine

BACKGROUND

The efficacy of procaine as anaesthetic for disbudding of calves is largely unknown. Likewise, information about effect of interval from local anaesthesia to disbudding and the size of the hot iron used is missing.

METHODS

A total of 167 dairy calves were disbudded after cornual nerve block with procaine. Time from administration of anaesthetic to disbudding varied, and calves were disbudded using two different sizes of hot iron. The calves' behavioural responses to disbudding were recorded based on (1) getting up, (2) kicking, and (3) lifting head. Using logistic regression, the associations between calves showing at least one of these three behaviours and interval from administration of anaesthetic to disbudding and size of the hot iron were evaluated.

RESULTS

Overall, 42% of calves showed at least one of the three behaviours, even though they had received a cornual nerve block prior to disbudding. Using the large hot iron was associated with a 2.3 times higher odds of the calf reacting behaviourally compared to the small iron. Interval from administration of anaesthetic to disbudding was not significantly associated with the odds of behavioural responses.

CONCLUSION

Approximately 40% of calves disbudded after cornual nerve block with procaine showed signs of inadequate local anaesthesia. This was especially problematic when hot irons with larger tips were used.

A multiparametric approach to assessing residual pain experienced by dairy cows undergoing digestive tract surgery under multimodal analgesia

This study assessed residual pain responses of dairy cows undergoing fistulation surgery under multimodal analgesia using a multiparametric method combining behavioural and physiological indicators. A longitudinal study was conducted on five dairy cows, each acting as her own control. The surgery consisted of implanting a ruminal and a duodenal cannula in each cow. The multimodal drug protocol consisted of a combination of N-Methyl-D aspartic Acid antagonists, α2-agonists, and local anaesthetic during surgery, and non-steroidal anti-inflammatory drugs (NSAIDs) and opioid treatment postsurgery. Cow responses to surgery were monitored by direct behavioural observation, physiological assay indicators, and milk production from day (D) -6 days before surgery (D-6) to D13 postsurgery. From the data recorded, the variables that contributed most to the discrimination of days pre- and postsurgery were identified using factorial discriminant analysis. Components 1 and 2 of the factorial discriminant analysis explained 68.2% and 17.9%, respectively, of the total variance. Component 1 was mainly explained by haptoglobin (contribution to axis: 0.885), oxidative stress (ratio of oxidized gluthatione to reduced glutathione (GSH/GSSG), -0.746; vitamin E, -0.683; vitamin A, -0.597; malondialdehyde (MDA), 0.416), and behavioural indicators (general attitude, 0.594). On this axis, the higher the score, the higher were the apathy and haptoglobin and MDA concentrations, and the lower were the GSH/GSSG ratio and concentrations of vitamins A and E. This axis opposed cows on D-6 to cows on D3 and D5; cows on D1 and D13 were intermediate. Component 2 was mainly explained by the Hypothalamic-pituitary-adrenal axis (non-esterified fatty acid (NEFA), 0.686; cortisol, 0.669), milk yield (-0.725), oxidative stress (MDA, -0.584; nitric oxide (NO), 0.454), and behavioural indicators of pain (ear position, 0.467; leg postures, 0.431). On this axis, the higher the score, the higher the NEFA, cortisol, and nitric oxide concentrations; the more the ear and leg pain postures; and the lower the milk production and MDA concentrations. This axis opposed cows on D13 to cows on D1. These results suggest that cows may experience some pain only on D1, whereas on subsequent days, the inflammatory response and oxidative stress did not seem to be associated with pain. Our results should be considered for different surgeries to improve analgesia immediately after surgery, and to provide antioxidants along with NSAIDs to promote recovery.

An Investigation into the Perceptions of Veterinarians towards Perioperative Pain Management in Calves

Simple Summary

Despite developments in animal welfare science regarding perioperative pain management in calves (Bos taurus), there are concerns that current knowledge has not been adopted in practice. Given that the perceptions of veterinarians have implications for how the welfare needs of calves are assessed and managed in practice, this study sought to quantify veterinary perceptions towards perioperative pain management in calves, including barriers to its use and whether demographic differences may influence those perceptions. A nationwide survey was electronically distributed to veterinarians registered with the Veterinary Council of New Zealand. Veterinarians largely associated multimodal pain management with the greatest reduction in perioperative pain. Most veterinarians also perceived that postprocedural pain persists beyond 24 h for disbudding and castration and did not support the use of differential treatment based on developmental age. Despite this, certain barriers were identified for their potential to inhibit the use of pain management on-farm. While demographic differences were found to influence veterinary perceptions towards perioperative pain management, the findings revealed considerable support among veterinarians for improving pain mitigation in calves. Given the opportunity, veterinarians in New Zealand would likely support strengthening the minimum provisions afforded to calves in practice and policy.

Abstract

While veterinarians are instrumental to the welfare of calves (Bos taurus), limited knowledge exists concerning veterinary perceptions towards perioperative pain management in calves. As a part of a larger, nationwide study investigating the perceptions of veterinarians towards calf welfare, the current work sought to quantify veterinary perceptions towards perioperative pain management, including barriers to its use, and investigate demographic influences affecting those perceptions. An electronic mixed-methods survey was completed by 104 veterinarians registered with the Veterinary Council of New Zealand. The current work revealed that most veterinarians considered a multimodal approach as the most effective method for ameliorating perioperative pain in calves, rejected the practice of differential treatment based on developmental age, and perceived that postprocedural pain persists beyond 24 h for the majority of procedures included in the survey. Despite this, veterinarians identified certain barriers that may inhibit the provision of pain mitigation on-farm, including costs, inadequate recognition of pain, and ingrained farming practices. Certain demographic effects were found to influence perceptions towards perioperative pain management, including gender, the number of years since graduation, and species emphasis. Nevertheless, the current work demonstrated considerable support among veterinarians to improve pain management protocols during routine husbandry procedures. The asymmetries that exist between the current minimum provisions of perioperative pain management and veterinary perspectives suggest that substantive improvements are necessary in order to reconcile New Zealand’s existing regulatory regime with developments in scientific knowledge.

Horn bud size of dairy-bred and suckler-bred calves at time of disbudding

BACKGROUND

Hot-iron disbudding is a common management procedure to prevent horn growth in calves. The study objective was to examine effect of age, breed and sex on horn bud size of dairy-bred and suckler-bred calves at time of disbudding.

RESULTS

The left and right horn bud size (diameter and height in mm) of 279 calves, including dairy-bred Holstein-Friesian (Male (M) = 88) and 191 suckler-bred (86 Charolais, CH; (M = 39, Female (F) = 47), 67 Limousin, LM; (M = 32, F = 35) and 38 Simmental, SI; (M = 22, F = 16) sired)) was measured using a digital calliper at time of disbudding. Calves were retrospectively assigned to two age categories at time of disbudding: 1), 14 to 28 days (d) old and 2), 29 to 60 d old. Holstein-Friesian M calves had a greater horn bud diameter (16.97 v.14.45 mm) and height (7.79 v. 5.00 mm) compared to suckler-bred M calves (P < 0.01), with no difference (P > 0.05) among the suckler-bred calves. Suckler-bred M calves had a greater horn bud diameter (14.46 vs 13.29 mm) and height (5.01 vs 3.88 mm) compared to suckler-bred F calves (P < 0.05). The slopes of the lines of best fit show that horn bud diameter and height increased with age (P < 0.05) for HF, SI male and CH female calves while there was no relationship with age (P > 0.05) for CH and LM male calves, or for SI and LM female calves. Linear regression of age with diameter and with height for each breed and sex showed high variability in the data as indicated by R-squared values ranging from 0.003-0.41 indicating that in the case of the diameter and the height, the weight of the fitting effect was poor.

CONCLUSIONS

Calf age is not a good predictor of horn bud size and recommendations for the disbudding of calves should be based on horn bud size and not on age. The implications of these findings are that calves should be disbudded while horn development is still at the bud stage and when the bud is large enough to be easily palpable/visible, but not so large that disbudding could lead to severe tissue trauma.

Pessimistic dairy calves are more vulnerable to pain-induced anhedonia

Pain induces deficits in appreciation of rewards (i.e. anhedonia) and variation in response to pain may be partly explained by individual differences in general expectations (i.e. optimism). Dairy calves are routinely subjected to painful procedures such as hot-iron disbudding. We tested if female Holstein calves (n = 17) display signs of anhedonia (as evidenced by reduced consumption of a sweet solution) after hot-iron disbudding (performed under general and local anesthesia), and whether individual differences in optimism explain the variation in this response. Individual variation in optimism was measured using responses to two judgment bias tests (performed when calves were 25 d old), and anhedonia was measured by comparing consumption of a sweet solution before and after hot-iron disbudding. We found that intake of the sweet solution declined (by mean ± SD: 48.4 ± 44.3%) on the day after disbudding, and that more pessimistic calves were more affected. Sweet solution consumption did not return to baseline for the duration of the study (i.e. 5 days). Calves reduced their intake of a sweet solution after hot-iron disbudding, consistent with pain-induced anhedonia, and more pessimistic calves showed stronger evidence of anhedonia, suggesting that they were more affected by the procedure. However, our results cannot rule out the possibility that calf responses were driven by anorexia.

Conditioned place aversion of caustic paste and hot-iron disbudding in dairy calves

Cauterization by hot iron and application of caustic paste are 2 common methods of disbudding calves. In this study, we compared the affective experience of these 2 procedures on young dairy calves using conditioned place aversion. Male dairy calves (n = 14; 7 ± 2 d old) were disbudded by both thermal and chemical methods (1 horn bud at a time, 48 h apart). Calves received treatments in pens made visually distinct with either red squares or blue triangles on the walls. Calves were restricted to these treatment pens for 6 h following disbudding. For all treatments, calves received a sedative (xylazine, 0.2 mg/kg), local anesthetic (lidocaine, 5 mL), and analgesic (meloxicam, 0.5 mg/kg). Calves were then tested for conditioned place aversion at 48, 72, and 96 h after their last treatment. During tests, calves were placed in a neutral pen connected to both treatment pens where they had previously been disbudded. Time spent in each treatment pen was recorded until calves chose to lie down for 1 min (latency to lie down: 31.0 ± 8.6 min). During the first test (48 h after last disbudding), calves spent more time in the pen associated with hot-iron disbudding compared with what would be expected by chance (intercept: 73.5%, 95% CI: 56.5, 90.5) and fewer calves lay down in the caustic paste pen than in the hot-iron pen (3 vs. 10 lying events). No evidence of preference for the hot-iron pen was found in the following test sessions (72 and 96 h since last disbudding). These results suggest that calves initially remember caustic paste disbudding as a more negative experience than hot-iron disbudding, even with the use of sedation, local anesthesia, and analgesia.

Organic Dairy Cattle: Do European Union Regulations Promote Animal Welfare?

Animal welfare is an emerging concept in EU law; with the advent of specific regulations intending to protect animals. The approach taken by European lawmakers is to provide "minimum standards" for conventional farming; argued by some as failing to adequately protect animals. In contrast, the EU organic farming regulations aim to "establish a sustainable management system for agriculture" and promote "high animal welfare standards". The first aim of this review was to identify key areas where there are clear improvements in quality of life for dairy cattle housed under the EU organic regulations when compared to the conventional EU regulations. Using the available scientific evidence, our second aim was to identify areas where the organic regulations fail to provide clear guidance in their pursuit to promote high standards of dairy cattle welfare. The greater emphasis placed on natural living conditions, the ban of some (but unfortunately not all) physical mutilations combined with clearer recommendations regarding housing conditions potentially position the organic dairy industry to achieve high standards of welfare. However, improvements in some sections are needed given that the regulations are often conveyed using vague language, provide exceptions or remain silent on some aspects. This review provides a critical reflection of some of these key areas related to on-farm aspects. To a lesser extent, post farm gate aspects are also discussed.

Disbudding affects use of a shelter provided to group-housed dairy calves

Disbudding in dairy calves is well established as a painful procedure with broad effects on behavior. The hypothesis of this experiment was that group-housed calves subjected to hot-iron disbudding would exhibit social withdrawal, based on use of a shelter providing physical and visual seclusion from the rest of the pen. We examined effects of hot-iron disbudding on use of this shelter, including individual and shared use, and resting behavior within the shelter. Holstein heifer and bull calves (n = 24) were housed in group pens (4 calves/pen; 3.7 × 8.0 m). Each pen contained a 3-sided open-top shelter (1.2 m square, and 1.2 m high) with an additional half-enclosed wall to allow entry, built out of corrugated plastic. Calves were randomly assigned within pen to be disbudded (n = 12; 10 bulls and 2 heifers; 36.2 ± 3.9 d of age) or receive sham handling only (n = 12; 9 bulls and 3 heifers; 36.3 ± 4.2 d of age). Disbudded calves received a local cornual nerve block and a nonsteroidal antiinflammatory medication before the procedure. Behavior was recorded continuously from video for 3 consecutive days, beginning immediately following the disbudding procedure or handling. Shelter use was highly variable between calves (ranging from 10.8 min/d to 20.7 h/d), but calves showed individual consistency in their use of the shelter over time. Disbudded calves spent more time in the shelter (4.6 vs. 1.6 h/d; disbudded vs. sham). Social use of the shelter as a percentage of shelter use was not affected by disbudding, but disbudded calves spent more time in the shelter together (31 vs. 9% of shelter use; disbudded vs. sham). Disbudded calves entered the shelter more frequently when it was unoccupied (8.1 vs. 5.5 entries; disbudded vs. sham) and similarly left it more frequently when it was occupied. Disbudded calves used the shelter more during daylight hours (0700 to 2000 h; 8.9 vs. 4.1 min/h) on each day, including d 0 when pain mitigation was effective, whereas use did not differ during the night. Disbudded calves spent approximately 40 min less time lying/d and spent a greater percentage of their lying time inside the shelter. These results suggest that disbudded calves make greater use of environmental features that offer seclusion, with use of the shelter possibly reflecting an increased preference for social withdrawal or for some other aspect of this area of visual and physical separation. Further, these results suggest that disbudding even with recommended pain mitigation affects behavior for at least several days.

Social approach and place aversion in relation to conspecific pain in dairy calves

Despite scientific interest in animal empathy, and growing public concern for farm animal welfare, the empathic abilities of farm animals remain under researched. In this study, we investigated empathic responses of young Holstein dairy calves to conspecifics recovering from hot-iron disbudding, a painful procedure common on dairy farms. A combination of social approach and place conditioning was used. First, 'observer' calves witnessed two 'demonstrator' calves recover from either a painful procedure (hot-iron disbudding and sedation) or a sham procedure (sedation alone) in distinct pens. Observer calves spent more time in proximity and paid more attention to calves recovering from the painful procedure compared to sham calves (proximity: 59.6 ± 4.3%; attention: 54.3 ± 1.5%). Observers were then tested for conditioned place aversion (in the absence of demonstrators) at 48h, 72h and 96h after the second demonstration; observers tended to avoid the pen associated with conspecific pain during the second of the three tests, spending 34.8 ± 9.6% of their time in this pen. No strong evidence of pain empathy was found, but our tentative results encourage further research on empathy in animals.

Conditioned place preference reveals ongoing pain in calves 3 weeks after disbudding

Hot-iron disbudding, a routine procedure that prevents horn bud growth through cauterization, is painful for calves. The resulting burns remain sensitive to touch for weeks, but it is unknown whether calves experience ongoing, non-evoked pain. We evaluated conditioned place preference for analgesia in 44 calves disbudded or sham-disbudded 6 hours (Day 0) or 20 days (Day 20) before testing (n = 11/treatment). Calves were conditioned to associate the effects of a lidocaine cornual nerve block with the location and pattern of a visual stimulus, and a control injection of saline with the contrasting stimulus. On Day 0, disbudded calves tended to prefer the lidocaine-paired stimulus over the saline-paired one, suggesting that they found analgesia rewarding. On Day 20, sham calves avoided the lidocaine-paired stimulus, consistent with humans’ experience of this drug being painful. Disbudded calves on Day 20 did not show this aversion, suggesting that they traded off the short-term pain of the lidocaine with the longer-term analgesia provided. Day 0 sham calves did not avoid the lidocaine-paired stimulus, likely because they received less than half the dose of Day 20 calves during conditioning. Thus, higher doses of lidocaine are aversive to uninjured animals, but disbudded calves are willing to engage in this cost. We conclude that calves experience ongoing pain 3 weeks after disbudding, raising additional welfare concerns about this procedure.

Optimized Genetic Testing for Polledness in Multiple Breeds of Cattle

Many breeds of modern cattle are naturally horned, and for sound husbandry management reasons the calves frequently undergo procedures to physically remove the horns by disbudding or dehorning. These procedures are however a welfare concern. Selective breeding for polledness - absence of horns - has been effective in some cattle breeds but not in others (Bos indicus genotypes) due in part to the complex genetics of horn phenotype. To address this problem different approaches to genetic testing which provide accurate early-in-life prediction of horn phenotype have been evaluated, initially using microsatellites (MSAT) and more recently single nucleotide polymorphism (SNP). A direct gene test is not effective given the genetic heterogeneity and large-sized sequence variants associated with polledness in different breeds. The current study investigated 39,943 animals of multiple breeds to assess the accuracy of available poll testing assays. While the standard SNP-based test was an improvement on the earlier MSAT haplotyping method, 1999 (9.69%) out of 20,636 animals tested with this SNP-based assay did not predict a genotype, most commonly associated with the Indicus-influenced breeds. The current study has developed an optimized poll gene test that resolved the vast majority of these 1999 unresolved animals, while the predicted genotypes of those previously resolved remained unchanged. Hence the optimized poll test successfully predicted a genotype in 99.96% of samples assessed. We demonstrated that a robust set of 5 SNPs can effectively determine P_C and P_F alleles and eliminate the ambiguous and undetermined results of poll gene testing previously identified as an issue in cattle.

Assessing the affective component of pain, and the efficacy of pain control, using conditioned place aversion in calves

Pain in animals is typically assessed using reflexive and physiological responses. These measures allow inferences regarding nociception but provide little basis for conclusions about the affective component of pain (i.e. how negatively the experience is perceived). Calves routinely undergo painful procedures on commercial farms, including hot-iron disbudding, providing a convenient model to study pain in animals. The aim of this study was to investigate the affective component of post-procedural pain due to hot-iron disbudding, using conditioned place aversion. Calves (n = 31) were subjected to two procedures (one bud at a time): one without post-procedural pain control and the other with the use of a nonsteroidal anti-inflammatory drug (either meloxicam (n = 16) or ketoprofen (n = 15)). All procedures included the use of local anaesthesia (lidocaine). Place conditioning was tested 2 days after the last treatment by allowing calves to freely roam between the pens where they had previously been disbudded. Calves spent more time, and lay down more frequently, in the pen where they received meloxicam compared with the pen where they only received a local block. Surprisingly, calves avoided the pen where they received ketoprofen compared with the control treatment pen. We hypothesize that the shorter duration of action of ketoprofen resulted in increasing pain at the end of the conditioning period, explaining the increased aversion to this treatment. These results illustrate the value of place conditioning paradigms to assess the affective component of pain in animals, and suggest that the animal's evaluation of painful events depends upon the time course of when the pain is experienced.

Calf aversion to hot-iron disbudding

Dairy calves are routinely disbudded by cauterization with a hot iron. To mitigate the intra-operative and initial post-operative pain associated with this procedure some farmers provide calves general and local anesthetics, but it is unknown if the procedure remains aversive. We used a place-conditioning paradigm to assess aversion caused by hot-iron cautery with a local anesthetic compared to a sham procedure. A test area was divided into three equally sized pens: two 'treatment' pens with distinct visual cues were connected by a central 'neutral' pen. Each calf went through the disbudding procedure and a 6-h recovery period in one treatment pen and the control procedure in the other treatment pen. In three tests (48, 72 and 96 h after the second treatment), calves could freely roam among the pens until they chose to lie down, ending the session. Calves spent less time in either of the treatment pens compared to the central pen. When only comparing the two treatment pen, calves spent less time in the disbudding pen, especially during the first test. Calves were also less likely to lie down in the pen associated with the disbudding procedure. We conclude that even with the use of a local anesthetic, hot-iron disbudding is salient and aversive for calves, indicating the need to refine or avoid the procedure.