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Can Vet J. Dec 2007; 48(12): 1249–1254.
PMCID: PMC2081989

Language: English | French

An investigation into the practices of dairy producers and veterinarians in dehorning dairy calves in Ontario

Abstract

The objective of this survey was to describe the current state of dehorning practices by dairy producers and veterinarians in Ontario and to identify opportunities to improve on existing practices. Two hundred and seven producers and 65 veterinarians completed a survey on dehorning practices during the summer of 2004. Seventy-eight percent of dairy producers dehorn their own calves; 22% use local anesthetics. Veterinarians dehorn calves for 31% of dairy clients; 92% use local anesthetics. Pain management was the most common reason for use of local anesthetics for both groups, while time (veterinarians) and time and cost (producers) were the most common reasons for lack of use. Producers who used local anesthetics were 6.5 times more likely to have veterinary involvement in their dehorning decisions. Thirteen percent of producers were unaware of the options for pain management. These results suggest that veterinarians should take the initiative to educate their clients about the options for pain management.

Résumé

Recherche sur les méthodes d’écornage des veaux laitiers par les producteurs laitiers et les vétérinaires en Ontario. L’objectif de cette enquête était de décrire les méthodes actuelles d’écornage pratiquées par les producteurs laitiers et les vétérinaires en Ontario et d’identifier les façons d’améliorer la situation. Deux-cent-sept producteurs et 65 vétérinaires ont répondu à une enquête sur les méthodes d’écornage au cours de l’été 2004. Dans 78 % des cas, les producteurs laitiers écornent eux-mêmes leurs veaux, 22 % utilisent un anesthésique local. Les vétérinaires écornent les veaux de 31 % de leurs clients laitiers, 92 % utilisent un anesthésique local. Dans les 2 groupes, le contrôle de la douleur était la raison principale de l’utilisation de l’anesthésie locale alors que le temps (vétérinaires) et le temps ainsi que le coût (producteurs) constituaient les principales raisons de la non utilisation. Les producteurs utilisant l’anesthésie locale étaient 6, 5 fois plus susceptibles de consulter leur vétérinaire dans le processus d’écornage. Treize pour cent des producteurs n’étaient pas au courant des possibilités de contrôle de la douleur. Ces résultats portent à penser que les vétérinaires devraient prendre l’initiative de sensibiliser leurs clients aux méthodes de contrôle de la douleur.

(Traduit par Docteur André Blouin)

Introduction

A survey conducted by Dairy Farmers of Canada in the fall of 2004 showed that 97% of Canadians believed that dairy farmers treat their animals well or very well (1). However, agricultural practices are coming under increasing scrutiny from the public and management practices commonly used may be negatively perceived, thus lowering the reputation of the industry. As research provides evidence for management changes, the dairy industry needs to be proactive in initiating changes to maintain this favorable view.

Dehorning dairy calves is a routine procedure in dairy cattle husbandry that is performed to reduce injury risk to the handlers and other cattle. Previous behavioral and physiological research has determined that dehorning is a painful experience, regardless of the method used (2, 3). Most countries have developed protocols regarding dehorning procedures; however, this legislation varies worldwide. In Australia, it is recommended that only animals less than 6 mo be dehorned without local anesthetics (4), while in Sweden, disbudding without local anesthetics and sedation is banned for any age (5). Calves less than 1 wk old may be dehorned with a caustic paste in the UK, but local anesthetics are required if other methods are used (6). The Canadian Code of Practice for dairy cattle recommends the use of a local anesthetic when dehorning dairy calves (7). The Codes of Practice are voluntary guidelines developed by organizations involved with the industry and are intended to promote the highest standard of husbandry. Despite these recommendations, it has been suggested that most calves are dehorned without the consideration of pain management (8).

Little is known about the practices currently being used by veterinary practitioners or dairy producers during dehorning of dairy calves in Ontario. A number of surveys have examined the demographics and attitudes surrounding animal welfare issues. Barnett et al (9) described the prevalence and attitudes of dairy producers in tail-docking cows. Results of a veterinary questionnaire assessing dairy calf health and welfare between birth and weaning were reported by Howard (10). However, none of these studies documented dehorning practices.

The objectives for this study were as follows: 1. to describe the current state of dehorning practices and pain management in Ontario by means of a representative sample of dairy producers and veterinary practitioners, and 2. to identify opportunities to improve on the methods currently being used by these groups.

Materials and methods

Survey design

Two surveys, 1 for dairy producers and 1 for bovine veterinarians, were developed to identify the dehorning practices currently used by each group. A draft survey was pre-tested on both producers and veterinarians in an attempt to clarify confusing questions.

Both surveys consisted of 4 main sections. The 1st section included demographic information, such as education level, age, and gender, which was hypothesized to provide potential variables related to dehorning practices. Producers were asked about their participation in herd health programs and veterinarians were asked about the number of herd health visits they performed. The 2nd section detailed the dehorning practices used. The questions asked about calf age at dehorning, methods used, and medications routinely used (lidocaine or other local anesthetics, nonsteroidal antinflamatory drugs [NSAID] use for post dehorning analgesia, xylazine for sedation, or all 3). Specifically, veterinarians and producers were asked about the proportion of calves that they dehorned within the age categories of calves < 4 wk, 4 to 8 wk, and > 8 wk of age. In addition, the proportion of calves dehorned by various methods and the use of local anesthetic, sedation, or both, for each method were queried. The 3rd section asked for the respondent’s reasons for determining use, or lack of use, of each medication. The 4th section investigated veterinary involvement in on-farm dehorning decisions. Producers were asked whether their veterinarian was involved in their dehorning decisions, and where they learned to perform nerve blocks, if applicable. Veterinarians were asked to estimate the number of clients that did their own dehorning and of those, the number that used nerve blocks.

Responses were given as a variety of answers, including percentages, yes/no answers, selections from a list, and open-ended questions. Respondents were also asked for any comments regarding the survey. Copies of the survey may be obtained by contacting the corresponding author.

Survey protocol

Three hundred and forty dairy farms in Ontario were randomly selected from the approximately 2000 Dairy Herd Improvement (DHI) members. Estimated sample size was calculated by using the results of a preliminary survey that indicated the prevalence of lidocaine use among dairy farmers to be within 5% with a confidence of 95%. Farms were selected with a proportional number representing the population of each region of the province. The survey was endorsed by the DHI agency. Herd information, including herd size, mean age at first calving, milk production, and breed, were obtained from the DHI to compare with survey responses.

One veterinarian was randomly selected from each licensed food-animal veterinary practice (n = 256) in Ontario (obtained from the College of Veterinarians of Ontario [CVO]). The CVO is the licensing body for veterinarians in Ontario and all practices that conduct food animal veterinary medicine on-farm must have a food animal mobile registered with the CVO. If the participant was not involved in dairy practice, he/she was asked to pass the survey to a member of the practice who qualified. Those practices no longer involved in food animal medicine were asked to return the survey to allow a more accurate list to be compiled, since practices may have a food animal mobile registered with the CVO but no longer conduct food animal practice.

The surveys were mailed with an accompanying letter of explanation and a self-addressed, stamped return envelope. The letter explained the purpose of the study and assured confidentiality to participants. Participants were instructed to fill out and return the survey within 10 d. As an incentive for completion, a gift certificate was offered for the first 20 respondents in each group and all respondents would receive a summary of the results. As well, participants were entered in a draw for a portable butane dehorner. Nonrespondents were telephoned 3 wk after mailing to remind them of the survey and give them the option of completing the survey over the phone.

Statistical analysis

Data for each group were entered into a database (Microsoft Access; Microsoft, Redmond, Washington USA) and converted into software files (SAS, version 8.2; SAS Institute, Cary, North Carolina, USA) for statistical analysis. Veterinarians and producers who did not dehorn any cattle were removed from the analysis.

Descriptive data for method, age, and reasons for use and lack of use were generated by using means and frequency tables. For main outcomes, such as proportion of producer and veterinary dehorned calves and proportion of calves dehorned by various methods, means, and standard errors were computed and 95% confidence intervals were reported. Two-way comparisons between survey variables and lidocaine use were performed by using 2 × 2 contingency tables. Significance was tested by using chi-square or Fisher’s exact test (when fewer than 5 observations in a cell). Those with a P-value of < 0.15 were included in a logistic regression model of lidocaine use. Backwards elimination was used to remove variables individually from the model, until all remaining variables had a P-value of < 0.05. A similar approach was used for xylazine.

Results

Response rates

Of the 256 veterinarians sent the questionnaire, 107 (42%) indicated that their practice was no longer involved in either dairy or food animal practice. Surveys were returned by 73 of the remaining 149 veterinarians for a response rate among veterinarians of 49%. Five veterinarians who did not respond to the initial mail survey were contacted successfully by telephone; 3 of these completed the survey (included in the 73 returned), and 2 declined. Eight of the 73 surveys were not included in the analysis due to incomplete or inconsistent data; 5 did not dehorn dairy cattle and 3 were missing data. Therefore, 65 of the veterinary surveys were included in the final results.

Surveys were returned (mail or phone) by 207 (61%) of the 340 dairy producers sent questionnaires. An attempt was made to telephone 122 producers who did not respond to the initial mail survey; the other nonresponders could not be contacted because of incorrect or lack of telephone contact information. Of the producers who were telephoned, 49 producers were contacted successfully and 42 responded to the survey over the phone.

Descriptive data

Producers dehorned 21%, 42%, and 37% of their calves at < 4 wk, 4 to 8 wk, and > 8 wk of age, respectively. These percentages were similar for veterinarians, with roughly 1/3 of calves being dehorned in each age category. However, the distribution of age of calves at dehorning reveals a much different pattern for veterinarians compared with producers. The age distribution of calves at dehorning is presented in Table 1 and the proportion of calves dehorned by various methods in Table 2. Veterinarians tended to dehorn calves throughout all age categories, whereas more producers dehorned all their calves at specific age categories. The most common method of dehorning within both groups was the electric hot iron.

Table 1
Distribution of age of calves at dehorning as reported by dairy producers and veterinarians
Table 2
Percentage of calves dehorned by each method of dehorning as reported by dairy producers and veterinarians

Use of medication

Overall, 78% (n = 161) (95% CI 72.5–82.6) of producers dehorned their own dairy calves. However, 9.2% (n = 19) of these producers dehorned some, but not all, of their own calves (range: 50% to 99% of calves). For those 161 producers who dehorned their own calves, 34 (21%) used a nerve block for at least some of their calves. Among the 34 producers performing nerve blocks, 29 (84%) used it in all of their calves. Nineteen (12%) of the 161 producers who dehorned their own calves used sedatives in dehorning, and of these, 16 (84%) used it for all calves. Xylazine use was significantly associated with lidocaine use (P = 0.0001), with 12 of the 19 xylazine users also using lidocaine. However, 7 producers reported using xylazine without lidocaine.

Veterinarians dehorned dairy calves for 31% (95% CI 26.1–35.1) of their dairy clients. Sixty (92%) of the 65 veterinarians used lidocaine for dehorning and used it on 83% of calves that they dehorned. Thirty-seven of the 60 veterinarians who used lidocaine used it in all calves. Lidocaine use among the remaining 23 veterinarians ranged from 1% to 99.8%. When the data on proportion of method used and lidocaine use are combined, the overall estimate of lidocaine use on calves dehorned by veterinarians indicates that veterinarians used local anesthetic on 77% of all the calves they dehorned. Sedatives were used by 39 (61) % of veterinarians in 35% of the calves they dehorned. Fourteen of the 39 veterinarians used xylazine for all calves, and the remaining 25 veterinarians used it selectively, ranging from 3% to 98% of the calves they dehorned. One respondent (1.5%) used NSAID’s in 8% of the calves he/she dehorned.

Attitudes about medication use

Producers —

Among producers (n = 34) using lidocaine, the most common reason for choosing to perform a nerve block was pain management (n = 31, 91%). Safety of calf and handler (n = 26, 76%) and restraint (n = 25, 73%) were also frequent explanations. Cost (n = 13, 38%) and availability (n = 12, 35%) were a factor for a smaller number of producers.

Logistic regression of the probability of producer lidocaine use indicated the following: producers that used lidocaine were 6.5 times more likely to have their veterinarian involved in their dehorning decisions (P = 0.005), 3 times more likely to use electric dehorning for all of their calves (P = 0.03), and 84% less likely to have Holstein cattle (P = 0.007). However, none of the producers that used paste for dehorning used a nerve block. When the model was adjusted for lack of lidocaine use among paste users, electric dehorning lost significance. Veterinary involvement (P = 0.007, OR 5.9) and breeds other than Holstein cattle (P = 0.004, OR 0.23) remained in the model. Several variables, such as herd size, education level of the producer, producer gender, frequency of herd health visits, and producer age, were not associated with the probability of lidocaine use.

Safety of the calf and handler (n = 15, 79%) was the main rationale for those producers using xylazine (n = 19). Other common reasons given were restraint (n = 12, 63%), pain control (n = 11, 58%), availability (n = 6, 32%), cost (n = 3, 16%), and other (n = 2, 10.5%).

Producers who did not use any xylazine (n = 142) cited other (n = 50, 35%), cost (n = 27, 19%), time (n = 26, 18%), method (n = 16, 11%), age (n = 12, 8%), and availability (n = 8, 6%) as their main reasons for choosing not to use sedation.

Veterinary involvement was the only variable that showed statistical significance in affecting producer xylazine use. If their veterinarian was involved in their dehorning decisions, producers were 7 times more likely to use xylazine (P = 0.0004).

Veterinarians —

Among veterinarians using lidocaine (n = 60), pain management (n = 52, 87%) was the most common reason for use. Restraint (n = 48, 78%), safety of calf and handler (n = 37, 62%), cost (n = 35, 58%), availability (n = 34, 53%), owner’s request (n = 16, 27%), and other (n = 2, 3%) were the other reasons given.

Lidocaine use by veterinarians displayed a dichotomous distribution. Most veterinarians that used lidocaine did so for all calves. Therefore, respondents were grouped as either 100% lidocaine use or less than 100% lidocaine use. Within these groups, it was found that veterinarians that used lidocaine in 100% of calves were 4 times more likely to consider cost as a reason for use (P = 0.0411), 7 times more likely to cite safety as a reason for use (P = 0.008), 90% less likely to use gouging as a method of dehorning (P = 0.0015), and 20 times more likely to employ a technician to perform dehorning (P = 0.03). However, veterinarians who used xylazine in all calves were more likely to perform a nerve block as well. If the model was adjusted to account for xylazine use, safety as a reason for use and gouge as a method of dehorning remained in the model. Variables, such as age or gender of the veterinarian, proportion of herds being on routine herd visit schedules, and average frequency of herd visits, were not associated with lidocaine use in all calves. Reasons for not using lidocaine in both producer and veterinary survey groups are illustrated in Figure 1.

Figure 1
Reasons for choosing not to use lidocaine in dehorning calves

Within veterinarians (n = 32) using gouging as a method of dehorning, 12 used gouging with 100% of the calves receiving a nerve block, and 20 used gouging with only 23% of the calves receiving a nerve block.

The majority (n = 40) of veterinarians who used xylazine chose to do so either for restraint purposes (n = 35, 87%) or for the safety of the calf and handler (n = 33, 82%). Pain control (n = 23, 57%), availability (n = 15, 37%), owner’s request (n = 10, 25%), cost (n = 8, 20%), and other (n = 2, 5%) were other reasons given.

Veterinarians (n = 51) who did not use xylazine cited time (n = 29%) and cost (n = 25%) as the most common reasons for lack of use. Method (n = 22%), age (n = 20%), and owner’s request (n = 18%) were the other choices.

Veterinarians who considered safety a reason for xylazine use were 15 times more likely to use xylazine in 100% of the calves they dehorned (P = 0.01).

Discussion

The desired 1st response rate for mail surveys is 40% to 57% (11). Mail surveys are considered reliable if they achieve a minimum response rate of 50% (12). The veterinary survey represents a survey of the entire target population rather than a survey of a sample of the population. This gives the 49% response rate a high accuracy. The fact that nearly half of the practices surveyed indicated that they are no longer doing food animal practice is a reflection of both the current accuracy of the CVO database for veterinary practice activity and the ongoing trend in agriculture toward consolidation of enterprises.

To the authors’ knowledge, this is the first survey to investigate dehorning practices. It provides new information on dehorning methods and attitudes about the practice in Ontario. Previously, it has been stated that dairy calves in North America are commonly dehorned without local anesthetics (8), but this statement was not quantified. The results of this study indicate that the proportion of calves receiving nerve blocks performed by producers is higher than expected. It may be that those producers who perform the procedure were more likely to answer the survey. The percentage of veterinarians dehorning calves for clients was more than the percentage of clients not dehorning calves (31% versus 21%). The confidence intervals around these estimates overlap and, therefore, are not statistically different. However, one possible explanation of the numeric difference is that although many producers dehorn most calves themselves, some producers have veterinarians dehorn some calves, especially those missed when calves were younger. This hypothesis is supported by the fact that 12% of the producers who indicated that they dehorned their own calves, actually dehorned less than 100% of their calves.

Electric dehorning was the most widely used method of dehorning, both in number of calves dehorned and in frequency of use. Roughly half of the veterinarians reported that they used gouge, a combination of gouge and electric cautery, and wire for dehorning, compared with relatively few producers that used these methods. However, only a small proportion of calves were dehorned by these methods. The most likely explanation of this discrepancy is that producers tend to use a particular method of dehorning because of experience and equipment with that method, while veterinarians carry tools and materials for several methods of dehorning. Veterinarians likely have a preference for certain methods and will tend to use these in conjunction with routine herd visits; however, they will occasionally either be asked by producers to dehorn with other methods or be forced to use other methods on some calves because of age or maturity of the horn. This view is supported by the differences in distribution of ages reported in Table 1 for veterinarians and producers. While there is a tendency for producers to dehorn at specific ages, veterinarians predominately dehorn calves across all age categories. Age of calf and dehorning method are somewhat correlated. Therefore, although the most common method for dehorning for both veterinarians and producers is the electric hot iron, those producers who dehorn predominately young calves tend to use the methods appropriate for that age, such as paste and a portable butane dehorner. Producers who dehorn at predominately more than 8 wk of age tend to dehorn more often with gouging and also have a higher rate of wire use, because the horns are bigger at this age and the hot iron will not work. Exact reasons why producers choose method or age of dehorning were not part of this survey, but they would provide an interesting follow-up to this questionnaire. Dehorning at a young age (ideally < 4 wk of age) is preferred because of ease of handling the calf and reduced trauma (smaller bud, less traumatic procedure). However, over 25% of producers had a program in place to dehorn calves, starting after the calf is 8 wk of age. Clearly this is an area for future client education.

Among producers who did not perform a nerve block, 40% chose “other” as a reason for not doing so. The responses given in the “other” category were divided into common themes: eleven percent (15/134) felt the procedure was unnecessary, and 13% (18/134) were unaware of the options for pain management. The frequencies of these answers indicate that education for producers regarding pain at dehorning and the choices available for pain management is needed. It is interesting that age categories for dehorning (<4 wk, 4 to 8 wk, >8 wk, or selective across all age categories) were not associated with lidocaine use. One could interpret from this that producers might be motivated to use lidocaine, regardless of the current age they dehorn calves. Likewise, if producers can be convinced to use lidocaine on older calves, they could likely be prompted to change their herd dehorning program to a younger age group.

The perception persists that pain management drugs for routine procedures like dehorning are prohibitively expensive. Producers who did not use local anesthetics for dehorning were most concerned about their cost and time (22% for each). Similarly, veterinarians cited cost (40%) as a reason for choosing not to use xylazine. However, the price per calf for an average dose is approximately $0.46 for lidocaine, $1.17 for xylazine, and $2.50 for ketoprofen (an NSAID). This calculation is based on the purchase price of a 100-mL bottle (lidocaine, ketoprofen) and a 50-mL bottle (xylazine) (personal communication, CDMV customer service representative)). Even when overhead and dispensing fees are included, the cost is minimal compared with the estimated cost of raising a heifer calf to maturity (13).

Other common reasons for veterinarians not using local anesthetics on some or all calves were age of the calf (22%) and method of dehorning (18%). However, multiple studies have shown that dehorning changes behavioral and physiological parameters indicative of pain, regardless of the age of the calf or method of dehorning (2,14,15). Interestingly, 57% of veterinarians used xylazine for pain management. However, xylazine and other alpha-2 agonists alone do not provide sufficient analgesia during dehorning, they should be combined with local anesthetics for maximum pain relief (2, 16).

Based on the logistic regression analyses, advice to producers regarding the involvement of their veterinarian in dehorning is the most important factor in the use of local anesthetics and sedatives prior to dehorning. This suggests that a significant number of producer dehorning practices might be improved by veterinary input. Furthermore, 22% of veterinarians said that they did not use local anesthetics before dehorning at the request of the owner. Therefore, veterinarians need to be aware of their influence and responsibility and they should set a standard protocol for local anesthetic use on all farms where they dehorn calves.

The design of the survey had several potential limitations that may have decreased responses. Despite the assurance of confidentiality for respondents, the inclusion in the survey of the producer and farm name to identify respondents and to obtain DHI information may have been a deterrent for some people. Similarly, the survey topic is potentially sensitive. We attempted to keep the wording neutral, but some may still have been hesitant of revealing their practices. A time deadline was indicated to urge completion. However, this may have been a disadvantage, as, after the deadline had passed, people may have been less likely to finish it. The timing of the survey may also have contributed to producers not responding; the survey was sent during the time of spring planting and farmers may have been too busy. Finally, self-selection bias is the greatest disadvantage of this type of survey. The people who answered the survey may not be typical of all dairy producers and veterinarians in Ontario; perhaps those who answered the survey were more likely to consider pain management and, therefore, were less concerned about disclosing their methods.

We attempted to address some of these issues in our design. The mail survey prevented interviewer bias and allowed people to respond at their convenience. Including self-addressed, stamped envelopes, using a follow-up telephone reminder, and offering incentives for completion of the survey are all methods that have been described as increasing response rate to postal surveys (12, 17).

The results of this survey indicated that most veterinarians follow the Canadian Code of Practice by using a local anesthetic for dehorning, while only 22% of producers do. Almost half of producers feel that pain management is not necessary for dehorning or are unaware that medications could be used. Veterinary involvement in the producer dehorning decision is the main factor influencing producer medication use for dehorning. Based on these results, education for producers regarding dehorning pain management is indicated. CVJ

Footnotes

Financial and in-kind support for this project was generously provided by Boehringer Ingelheim Canada, CanWest DHI, the Ontario Ministry of Agriculture and Food, and the OVC Summer Leadership and Research Program.

References

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