Reducing Pain After Dehorning in Dairy Calves. P. M. Faulkner*,1 and D. M. Weary. Animal Welfare Program, Faculty of Agricultural Sciences and Centre for ...
Reducing Pain After Dehorning in Dairy Calves P. M. Faulkner*,1 and D. M. Weary Animal Welfare Program, Faculty of Agricultural Sciences and Centre for Applied Ethics University of British Columbia, Vancouver, Canada V6T 1Z4
ABSTRACT We investigated behavioral responses after dehorning and a sham procedure in 20 Holstein calves aged 4 to 8 wk. Calves either received a nonsteroidal antiinflammatory drug (ketoprofen) before dehorning as well as 2 and 7 h after the procedure or were assigned to a control group. All calves received a sedative (xylazine) and local anaesthetic (lidocaine) before dehorning, and responses were scored over 24 h after the procedure. After hot-iron dehorning, calves treated with ketoprofen also demonstrated little head shaking or ear flicking, but control animals demonstrated higher frequencies of these behaviors; both responses peaked 6 h after dehorning. Differences between the treatment groups remained statistically significant until 12 h (head shaking) and 24 h (ear flicking) after dehorning. A low frequency of head rubbing was observed in both treatment groups, but control calves were more frequently observed engaged in this behavior. There was no statistically significant effect of treatment on any of the other behavioral measures. Calves treated with ketoprofen also tended to gain more weight (1.2 ± 0.4 kg) during the 24 h after dehorning than did control calves (0.2 ± 0.4 kg). There was no effect of treatment on any of the response variables when calves were sham dehorned. These results indicate that ketoprofen mitigates pain after hot-iron dehorning in young dairy calves. (Key words: dehorning, local anesthesia, analgesia, behavior) INTRODUCTION Horn buds of young dairy and beef calves are normally removed to reduce the risk of injuries to farm workers or other cattle that can be caused by horns. Damage from horns can also result in reduced milk production and growth (6) and complications associated with open wounds such as infection or fly strike. Cattle with horns are harder to handle in yards and chutes,
Received December 1, 1999. Accepted March 21, 2000. Corresponding author: D. M. Weary; e-mail: danweary@ interchange.ubc.ca. 1 Current address: 13 Hares Chase, Billericay, Essex, UK CM12 0HJ. 2000 J Dairy Sci 83:2037–2041
require three times more space at a feed trough and during transport (12), and may also suffer financial penalties on sale. Dehorning should be done when the calf is less than 3 mo of age (1, 3). The developing horns of calves 3 mo of age or older are normally removed surgically by a number of techniques (e.g., scooping, shearing, and sawing), and physiological responses suggest that these procedures are painful (15). Horn buds of younger calves are typically removed with a caustic paste or a hot iron. There is evidence that both methods are painful (13), but the latter is more commonly used on dairy calves. Even when the procedure is performed at an early age, hot-iron dehorning causes a pronounced behavioral response such that significant physical restraint is necessary to carry out the procedure. Increased levels of circulating corticosteroids, reflecting changes in the hypothalamus-pituitary-adrenal axis (16), are commonly detected after dehorning (2, 10, 13, 14, 17). Administration of a local analgesic dampens the initial increase in plasma cortisol. Local analgesics also reduce behaviors associated with the immediate pain response (e.g., tail wagging, head movements, tripping, and rearing) and those indicative of postoperative pain (head rubbing, head shaking, and ear flicking) (4, 12, 13, 15). In the United Kingdom, calves dehorned after 7 d of age must receive local anaesthetic [The Protection of Animals (Anaesthetics) Act, 1964]. The Canadian code of practice recommends using local anaesthetic for dehorning (1), but a common practice in North America is to perform the procedure without analgesics or anaesthetics. Local anaesthetics are effective in reducing the immediate pain response after dehorning; however, the use of local anaesthetic alone is unsatisfactory on at least two counts. First, calves respond to the pain of the procedure and to the physical restraint. Calves dehorned using a local anaesthetic still require restraint, and the difference in the behavioral response between treated and untreated calves can be sufficiently subtle that it is difficult for observers to be certain if adequate nerve blockage was achieved. Calves must also be restrained while the local anaesthetic is administered and during the actual dehorning. Thus, calves experience the distress associated with restraint on two occasions, and still may not receive an adequate nerve block.
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A second unsatisfactory aspect is that local anaesthetic does not provide adequate postoperative pain relief. The most popular local anaesthetic, lidocaine, is effective for only 2 to 3 h after administration (10, 11). Bupivacaine is effective for approximately 4 h, but the pain after dehorning can persist for at least 6 h (10, 11). Indeed, the results of recent studies indicate that calves treated with local anesthetic actually experience higher plasma cortisol levels than untreated animals after the local anaesthetic loses its effectiveness (4, 10, 11, 14). Thus, the inflammatory response to the burn injury, and associated pain, appears to be delayed but not prevented by the use of local anaesthetic (11). McMeekan et al. (11) showed that providing nonsteroidal anti-inflammatory drugs, in addition to a local anaesthetic, can keep plasma cortisol to baseline levels for as long as 6 h after scoop dehorning at 3 to 4 mo of age. However, cauterization after surgical dehorning can itself reduce signs of postoperative pain (14). Indeed, Petrie et al. (14) showed that the postoperative surge in cortisol for calves treated with local anaesthetic occurred after scoop dehorning but not hot-iron dehorning. Thus it is not clear if nonsteroidal antiinflammatory drugs will affect postoperative pain after hot-iron dehorning. The aim of the present study was to assess the effectiveness of ketoprofen, a nonsteroidal anti-inflammatory drug, in decreasing the pain response during the 24-h period after hot-iron dehorning. To assess the pain response, we used noninvasive behavioral measures that have been validated in previous work (4, 12, 13). Ketoprofen was administered pre- and postoperatively. All animals received local anaesthetic. To remove the need for restraint during dehorning and the administration of the local anaesthetic, all animals were sedated with xylazine. The experiment consisted of two components. In the first, calves were sham dehorned (all aspects of the procedure identical to actual dehorning, but the dehorning iron was kept at room temperature) with or without ketoprofen. This part of the experiment allowed us to assess any general effects of the ketoprofen on the calves. In the second component, calves were actually dehorned, again with or without ketoprofen, allowing us to assess the effectiveness of the drug on the calves’ response to postoperative pain. MATERIALS AND METHODS Twenty Holstein calves of both sexes were used. Calves were between 4 to 8 wk of age and weighed 58.3 to 95.2 kg. Calves were fed whole milk at 5% BW twice daily. Hay, calf starter, and water were available for consumption ad libitum. Animals were housed singly in sawdust-bedded pens measuring 1.7 × 1.2 m. Journal of Dairy Science Vol. 83, No. 9, 2000
All calves were sham dehorned one day and dehorned 2 d later. For both procedures, an electrically heated hot-iron dehorner (Rhinehart X30, Rhinehart Development Corporation, Spencerville, IN) was applied to each horn bud for approximately 35 s. During the sham procedure, the device was switched off, and the tip was at room temperature. During actual dehornings, the iron was on and had been preheated for at least 10 min to a temperature of approximately 600°C. Both procedures were carried out by the same person and at the same time of day (10:00 a.m.) in the animals’ own pens. Before sham and actual dehornings, animals were given xylazine intramuscularly at a dose of 0.2 mg/kg (Rompun 2%, Bayer Inc., Ontario). Xylazine acts as a potent sedative in calves, and all animals were recumbent (positioned sternally) and fully sedated within 10 min (range 70 s to 9.5 min, with no difference between treatments). Ten minutes after administration of the xyalzine, the local anaesthetic (4.5 ml per side of 2% Lidocaine HCl; Ayerst Veterinary Labs, Ontario) was injected subcutaneously around the cornual nerve (located along the occipital groove midway between the horn bud and eye), and also as a ring block around each horn bud. Dehorning or sham dehorning took place 10 min after administration of the local anaesthetic (20 min after administration of the xylazine). The use of the xylazine sedative eliminated calf response to the administration of the local anaesthetic and the need for physical restraint during the administration of the local anaesthetic or during dehorning. Although xylazine is indicated as having analgesic properties, calves treated only with the xylazine show a strong behavioral response to application of the hot iron, but the combination of local anaesthetic and xylazine sedative essentially eliminates the immediate response (5). Within sex, calves were alternately assigned to control or ketoprofen treatment groups. The latter were given liquid ketoprofen (10% Anafen; Rhoˆ ne Me´ rieux Inc., USA) orally at a dose of 3 mg/kg in the morning and evening milk rations (2 h predehorning and 7 h postdehorning) and in an additional 1 L of milk given 2 h after dehorning. Control animals received the same three milk meals without ketoprofen. We observed calf behavior for 8 20-min periods at 1, 2, 3, 4, 6, 9, 12, and 24 h after dehorning. During observations we recorded the frequency of three behaviors previously associated with pain after dehorning: head shaking, ear flicking (twitching of both ears when no flies present), and head rubbing (with hind leg or against the sides of the pen). We also recorded frequencies of feeding (head in feed bucket), exploring pen (sniffing walls or bedding), locomotion (all four legs move at least once), self grooming, head-out-of-pen (tip
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REDUCING PAIN AFTER DEHORNING IN DAIRY CALVES Table 1. Mean (± SEM) time (min) spent lying down and frequency (all other behaviors). Means are from 20-min observation sessions occuring 3, 4, 6, 9, 12, and 24 h after h dehorning or sham dehorning. Calves were all sham-dehorned and them dehorned either as controls (n = 10) or using ketoprofen (n = 10). Sham Behavior
Control
Shake head Flick ear Rub head Move Lie Groom Vocalise Feed Drink
0.05 0.00 0.00 0.93 13.47 3.13 0.07 1.10 0.28
± ± ± ± ± ± ± ± ±
Dehorned Ketoprofen
0.03 0.00 0.00 0.21 0.68 0.76 0.04 0.27 0.07
0.02 0.02 0.00 1.10 14.38 1.81 0.28 0.73 0.20
± ± ± ± ± ± ± ± ±
0.02 0.02 0.00 0.26 1.11 0.30 0.17 0.20 0.06
Control 6.27 11.43 1.60 0.42 16.38 1.70 0.75 0.47 0.07
± ± ± ± ± ± ± ± ±
Ketoprofen 2.57 3.07 0.41 0.07 0.72 0.42 0.70 0.18 0.03
0.74 0.56 0.70 0.55 16.38 1.48 0.00 0.49 0.09
± ± ± ± ± ± ± ± ±
0.25 0.17 0.31 0.13 0.91 0.29 0.00 0.10 0.05
of the nose extended through an opening in the pen), and vocalization. Time spent lying down during the observation period was also recorded. All observations were by the same person, who was blind to treatment. Calves were weighed on an electronic scale (± 0.05 kg) at 9:00 a.m. on the day of sham and actual dehorning and on the next 2 d. As a result of the xylazine sedative, all calves were relatively inactive during the first 2 h after dehorning, so mean differences reported in Table 1 were calculated with responses 3 to 24 h after dehorning. Dependent variables were square root transformed to normalize variances before analysis. Treatment differences varied with time after dehorning, so the effect of treatment (1 df) was tested separately at each period using analysis of variance (residual df = 18). RESULTS Behavior after sham dehorning was similar for control and ketoprofen-treated calves (Table 1). There was no statistically significant (P < 0.1) effect of treatment on any of the behavioral measures after sham dehorning, and the frequencies of pain related behaviors (head shaking, ear flicking, and head rubbing) were near zero for both control and treated calves. After hot-iron dehorning, calves treated with ketoprofen also showed little head shaking, ear flicking, and head rubbing, but control animals showed much higher frequencies of these behaviors. Because the magnitude of this treatment effect varied with time after dehorning (Figure 1), the effect was tested separately for each of the eight observational periods. Calves treated with ketoprofen showed almost no head shaking or ear flicking throughout the 24 h after dehorning (Figure 1a and b). Control calves were frequently observed head shaking and ear flicking, with both responses peaking 6 h after dehorning. The effect of the ketoprofen was statistically significant from 3 to 12 h after dehorning
Figure 1. Mean (± SEM) behaviors of calves dehorned as controls (empty bars, n = 10) or with ketoprofen (filled bars, n = 10). Results are shown in relation to time after the dehorning. Data are shown separately for the frequency of a) head shaking, b) ear flicking, and c) head rubbing. Treatment differences were tested separately at each of the eight times after dehorning. (*signifies P < 0.05; **signifies P < 0.01 in a one-way ANOVA). Journal of Dairy Science Vol. 83, No. 9, 2000
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for head shaking, and from 3 to 24 h after dehorning for ear flicking. A lower frequency of head rubbing was observed in both treatment groups, but control calves were more frequently observed engaged in this behavior, significantly so at 4 and 12 h after dehorning (Figure 1c). There was no statistically significant (P < 0.1) effect of treatment on any of the other behavioral measures. Mean (± SEM) BW was similar for ketoprofen-treated (73.5 ± 3.5 kg) and control calves (76.7 ± 3.7 kg) (P > 0.1). However, calves treated with ketoprofen tended to gain more weight (1.2 ± 0.4 kg) during the 24 h after dehorning than did control calves (0.2 ± 0.4 kg) (P = 0.07). During the subsequent 24-h period, weight gains were similar for treated (1.0 ± 0.2 kg) and control calves (1.1 ± 0.4 kg) (P > 0.1). DISCUSSION The ketoprofen had no discernible effect on the calves after sham dehorning. After recovery from the sedative, both sham-dehorned groups (control and ketoprofen treated) behaved similarly and in what appeared to be a normal manner, with frequencies of pain-related behaviors (head shaking, ear flicking, and head rubbing) near zero in both groups. In contrast, the ketoprofen had a pronounced effect on head shaking and ear flicking after actual dehorning; control calves engaged in these behaviors frequently, but ketoprofen-treated calves rarely performed these. The effects of ketoprofen on head rubbing were also significant, but less impressive than the effects of the other two pain-related behaviors. Why the treatment was less effective in reducing the frequency of head rubbing is not clear. Our results provide the first behavioral evidence of the effectiveness of a nonsteroidal anti-inflammatory drug in reducing pain after hot-iron dehorning. The ketoprofen had no general effects on behavior, but essentially eliminated two behaviors previously identified as related to postoperative pain. Our behavioral results correspond well with the physiological results of McMeekan et al. (11). These authors found that the plasma cortisol increase that normally follows dehorning could be much reduced by providing animals with ketoprofen. That study also showed a peak response in control animals approximately 6 h after dehorning. The results from the current study show less agreement with another recent experiment by the same authors (12). The trends observed in that study are in the same direction as we report, but they found no significant behavioral differences between animals treated with ketoprofen combined with local anaesthetic versus those treated with the local anaesthetic alone. Several differences in methodology between the two studies could account for this difference in results. Journal of Dairy Science Vol. 83, No. 9, 2000
For example, we used a different method of dehorning (hot iron vs. scoop dehorning) and younger calves (1 to 2 mo of age vs. 3 to 4 mo of age). Our results, showing a surge in pain-related behaviors 3 to 12 h after hot-iron dehorning of local anaesthetic treated calves, are not consistent with Sylvester et al. (15) who showed that cauterization may help prevent postoperative pain. These authors showed a surge in cortisol 3 to 7 h after scoop dehorning of calves treated with a local anaesthetic, but no surge when the wound left by the scoop was cauterized. Similarly, Petrie et al. (14) reported a surge in cortisol 3 to 7 h after scoop dehorning but not after hot-iron dehorning. However, neither of these studies reported behavioral differences. It may be that behavioral responses provide a more sensitive means of assessing this postoperative pain than does plasma cortisol. Ketoprofen is known to clear quickly from the body (half life = 0.42 h; 7), but can persist in inflamed tissues at higher concentrations (8). We found that the frequencies of head shaking and ear flicking remained lower in treated calves 12 to 24 h after dehorning, some 5 to 17 h after the last ketoprofen was administered. McMeekan et al. (11) found a reduced cortisol response for 6 h after dehorning, but after 9 h the cortisol concentrations were higher in treated calves than in controls. Again, differences in methodology between the two studies may account for this difference in results. For example, in our study the ketoprofen was combined with milk and provided orally on three occasions, compared with the single intravenous administration used by McMeekan et al. (11). We found a tendency for calves dehorned with ketoprofen to gain more weight on the day after the procedure. Other work on nonsteroidal anti-inflammatory drugs and dehorning has not examined effects on weight gain. Grøndahl-Nielsen et al. (5) found no difference in gain in relation to the use of sedation or local anaesthetic during dehorning, but some earlier work has shown negative effects of dehorning on subsequent gains (9). In conclusion, ketoprofen administered in the milk reduced behavioral evidence of pain after hot-iron dehorning in dairy calves. We recommend a combination of three treatments for calves being dehorned: a sedative (such as xylazine), a local anaesthetic (such as lidocaine), and a nonsteroidal anti-inflammatory drug (such as ketoprofen). The use of a sedative allows for careful administration of the local anaesthetic, with no response by the calf. The combination of sedative and local anaesthetic allows for dehorning with no immediate behavioral response. The combination of sedative, local anaesthetic, and a nonsteroidal anti-inflammatory
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drug reduces the response to the pain both during dehorning and in the hours that follow.
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ACKNOWLEDGMENTS We thank Jim Love for his many contributions and especially for his help in designing this approach to pain management. We are also grateful to the students and staff of the UBC Dairy Education and Research Centre for their help and cooperation, and Ruth Forde, David Fraser, and Cassandra Tucker for their comments on earlier drafts of this manuscript and support at all stages of the study. This work was supported by National Sciences and Engineering Research Council through the Industrial Research Chair in Animal Welfare, and by contributions from the Dairy Farmers of Canada, the Cattle Industry Development Fund, the BC Dairy Foundation, the BC SPCA, members of the BC VMA and many other donors listed on our web site at www.agsci.ubc.ca/animalwelfare.
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REFERENCES 1 Agriculture Canada. 1990. Recommended Code of Practice for the Care and Handling of Dairy Cattle. Agriculture Canada, Ottawa. 2 Boandl, K. E., J. E. Wohlt, and R. V.Carsia. 1989. Effects of handling, administration of a local anaesthetic, and electrical dehorning on plasma cortisol in Holstein calves. J. Dairy Sci. 72:2193–2197. 3 Farm Animal Welfare Council. 1997. Farm Animal Welfare Council’s Report on the Welfare of Dairy Cattle. Ministry of Agriculture Fisheries and Food, Surbiton, UK. 4 Graf, B., and M. Senn. 1999. Behavioural and physiological responses of calves to dehorning by heat cauterisation with or without local anaesthesia. Appl. Anim. Behav. Sci. 62:153–171. 5 Grøndahl-Nielsen, C., H. B. Simonsen, J. Damkjer Lund, and H. Hesselholt. 1999. Behavioural, endocrine and cardiac responses
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in young calves undergoing dehorning without and with the use of sedation and analgesia. Vet. J. 158:14–20. Laden, S. A., J. E. Wohlt, P. K. Zajac, and R. V. Carsia. 1989. Effects of stress from electrical dehorning on feed intake, growth and blood constituents of Holstein heifer calves. J. Dairy Sci. 68:3062–3066. Landoni, M. F., F. M. Cunningham, and P. Lees. 1995. Pharmacokinetics and pharmacodynamics of ketoprofen in calves applying PK/PD modelling. J. Vet. Pharmacol. Ther. 18:315–324. Landoni, M. F., and P. Lees. 1995. Pharmacokinetics and pharmacodynamics of ketoprofen enantomers in the horse. J. Vet. Pharmacol. Ther. 19:466–474. Loxton, T. D., M. A. Toleman, and A. E. Holmes. 1982. The effect of dehorning Brahman crossbred animals of four age groups on subsequent bodyweight gain. Aust. Vet. J. 58:191–193. McMeekan, C. M., D. J. Mellor, K. J. Stafford, R. A. Bruce, R. N. Ward, and N. G. Gregory. 1998. Effects of local anaesthesia of 4 to 8 hours’ duration on the acute cortisol response to scoop dehorning in calves. Aust. Vet. J. 76:281–285. McMeekan, C. M., K. J. Stafford, D. J. Mellor, R. A. Bruce, R. N. Ward, and N. G. Gregory. 1998. Effects of regional analgesia and/ or nonsteroidal anti-inflammatory analgesic on the acute cortisol response to dehorning calves. Res. Vet. Sci. 64:147–150. McMeekan, C. M., K. J. Stafford, D. J. Mellor, R. A. Bruce, R. N. Ward, and N. G. Gregory. 1999. Effects of a local anaesthetic and a nonsteroidal anti-inflammatory analgesic on the behavioural responses of calves to dehorning. N.Z. Vet. J. 47:92–96. Morisse, J. P., J. P. Cotte, and D. Huonnic. 1995. Effect of dehorning on behaviour and plasma cortisol responses in young calves. Appl. Anim. Behav. Sci. 43:239–247. Petrie, N. J., D. J. Mellor, K. J. Stafford, R. A. Bruce, and R. N. Ward. 1996. Cortisol responses of calves to two methods of disbudding used with or without local anaesthetic. N.Z. Vet. J. 44:9–14. Sylvester, S. P., D. J. Mellor, K. J. Stafford, R. A. Bruce, and R. N. Ward. 1998. Acute cortisol responses of calves to scoop dehorning using local anaesthesia and/or cautery of the wound. Aust. Vet. J. 76:118–122. Terlouw, E. M. C., W.G.P. Schouten, and J. Ladewig. 1997. Physiology. Pages 143–158 in Animal Welfare. Appleby, M. C. and B. O. Hughes, eds. CAB International, Wallingford, UK. Wohlt, J. E., M. E. Allyn, P. K. Zajac, and L. S. Katz. 1994. Cortisol increases in plasma of Holstein heifer calves from handling and method of electrical dehorning. J. Dairy Sci. 77:3725–3729.
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