Approximately 15 million calves are castrated in the United States annually  yet little has been published with regards to methods of castration used by U.S. veterinarians. The objective of this survey was to describe castration methods, adverse events and husbandry procedures performed by bovine practitioners at the time of castration. The results of this survey suggest that surgical castration with a scalpel followed by testicular removal using either manual twisting (cattle <90 kg) or an emasculator (cattle >90 kg) are the most common castration methods used by veterinarians. Survey participants indicated that the potential risk of injury to the operator, the size of the animal, the availability and quality of handling facilities and experience with the technique were the most important factors considered when choosing a castration method. The most prevalent adverse events observed by respondents following castration were swelling, stiffness and increased lying time. In terms of preoperative analgesia, one in five respondents reported providing systemic analgesia or local anesthetic at the time of castration. It is noteworthy that approximately 90% of respondents report that they vaccinate and dehorning calves at the same time as these are castrated. Over half the respondents reported using disinfectants, prophylactic antimicrobials and tetanus toxoid in an attempt to reduce complications associated with castration. To our knowledge, this is the first report describing bovine castration methods and associated management practices employed by veterinarians in the United States. These data are necessary to guide future animal well-being research so that the outcomes can be used to develop industry-relevant welfare guidelines.
Some caution is appropriate in interpreting the results of the present study given the relatively low crude response rate of 9.6% which may have introduced a degree of non-response error. However, it is relevant that a recent survey of the same population of rural veterinarians conducted by the Food Supply Veterinary Medicine Coalition had a 10.4% response rate (133/1,280) in new graduates and an 8% response rate in long term veterinarians . This suggests that low response rates may be typical of this study population in the United States. Several recent studies have also challenged the presumption that lower survey response rates imply lower survey accuracy . This suggests that the results presented provide a meaningful first attempt at describing castration methods used by veterinarians in the U.S.
Other potential sources of bias in this study are similar to those highlighted in previous surveys and include coverage bias, sampling error, measurement error and response bias . In terms of addressing coverage bias and sampling error, all email recipients of the invitation to participate in the survey identified themselves as veterinarians. However, it is significant that the mailing list used did not differentiate between AABP or AVC members in industry, practice and academia. The current AABP membership list only identifies 66% of members as being associated with veterinary practices. Therefore, not all survey recipients were involved in castrating calves but all were included in the denominator of the response rate calculation. This may have contributed to the lower response rate. Nonresponse could also be attributed to the length of the survey, the time of the year the survey was conducted (September - November) and that this same population had been recently surveyed for analgesic drug use  and job satisfaction . Measurement error was reduced by pretesting the survey on veterinarians associated with the Beef Cattle Institute at Kansas State University and the AABP-AWC. In common with previous reports, response bias ("faking good" biases) was not assessed in this survey . However, the effect or response bias was minimized by providing assurances that all data were confidential and that the researchers were not looking for right or wrong answers.
The demographic characteristics of the respondents in this survey were similar to those participating in a recent Canadian survey . Both surveys enrolled more men who were older and engaged in smaller practices than have been reported in companion animal surveys. The majority of respondents from this study were from Iowa, Minnesota, Missouri, Nebraska, North Dakota and South Dakota which are states that account for 24% of the U.S. cattle inventory . The second highest participation came from Illinois, Indiana and Wisconsin and Arizona, Colorado, Kansas, New Mexico, Oklahoma, and Utah which account for a further 23% of the U.S. cattle inventory .
Surveys of methods used by veterinarians to castrate calves are deficient in the published literature. However, results from similar surveys of farmers in the United Kingdom, New Zealand and the United States have been reported [17–19]. Since these surveys involve distinctly different populations, direct comparison between these reports and the present study should be interpreted with caution. However, in the absence of analogous studies, some comparisons between these reports may be relevant. Kent and others found that non-surgical castration methods were preferred by British farmers with 43% of respondents indicating that they used Burdizzo clamp castration . However, UK producers preferred surgical castration in older calves with 68% indicating that these were conducted by veterinarians. These results are in agreement with the results presented here with 68% of respondents indicating that veterinarians were primarily involved in castrating heavy weight calves with 58% indicating that they prefer surgical castration methods. The preference for U.S. veterinarians to perform surgical castrations is likely due to client expectations and a greater level of comfort and experience with surgical procedures.
Removal of testicles with a blade was the most common method of castration performed by almost 50% of beef producers in the United States as reported by the NAHMS survey . Only 3.5% of producers report using a burdizzo clamp compared with 39.5% of producers that report using a rubber ring or tubing in calves less than 3 months of age. Stafford and others reported that 85% of New Zealand producers preferred rubber ring castration, especially in the first 3 months of life, with 18% performing surgical castration mostly in older calves . In contrast with the U.K survey, only 2.7% of New Zealand producers indicated that they used a veterinarian to perform castrations. This difference is likely due to the legislative requirement in the UK for older calves to be castrated by a veterinarian . It is noteworthy that banding of heavy weight calves was not reported in the British and New Zealand producer survey yet over 53% of U.S. veterinarians report using banders to castrate heavy weight calves. Furthermore, neither survey reported the use of the Henderson castration tool to castrate calves. This finding likely represents differences in regional preferences between the study locations.
Factors affecting selection of a castration method have not been described in the published literature. For the majority of respondents the risk of injury to the operator was the most critically important consideration in the selection of castration method. This would seem to contradict the finding of our survey that surgical castration, which is arguably more hazardous than non-surgical castration, is preferred by veterinarians. However, as stated previously, the preference for using surgical castration methods by veterinarians is likely due to client expectations that surgical as opposed to non-surgical castration is performed by veterinarians. Concern for operator safety is justified based on a recent survey of Australian veterinarians which found that cattle related injuries accounted for 22% of all the significant injuries reported by veterinarians . Scalpel or knife injuries accounted for 28% of the surgical injuries reported. It is noteworthy that only 13% of veterinarians considered the painfulness of procedure to be a critically important consideration in the selection of castration method. This finding is in agreement with a recent Canadian survey where veterinarians gave castration up to 6 months of age the lowest pain rating (4.6/10) with dehorning in the same age group receiving a pain rating of 7.2/10 .
The incidence of complications associated with castration reported by British farmers was low with 28% indicating that complications were most commonly associated with surgical castration . A few New Zealand respondents reported swelling (2.9%), deaths (1%), infection (0.7%) or bleeding (0.6%) particularly after surgical castration . Neither survey related the incidence of complication to weight or age at the time of castration. In the present report, more veterinarians indicated that swelling, stiffness and recumbency occurred more than half the time following both surgical and non-surgical castration in heavy weight calves (>270 kg) compared with perinatal and light weight calves (p < 0.0001). In contrast with previous reports, U.S. respondents indicated that more complications were associated with non-surgical than surgical castration. Furthermore, the overall incidence of adverse events reported by veterinarians in the present survey was higher than previously reported by producers. This difference is likely due to veterinarians being specifically consulted about adverse events following castration and may thus be exposed to a biased population.
The effect of age and method of castration on the health and performance of calves has been reviewed elsewhere . Several studies have compared the effects of surgical and non-surgical castration in bulls but results have been conflicting. Stafford and others found that peak cortisol response was higher in 2-4 month old calves after latex band castration compared with surgical castration but this difference was not statistically significant . These researchers also found that cortisol response remained above baseline levels for 180 minutes following both surgical and non-surgical castration. Fisher and others concluded that banding produced fewer acute effects, but greater suppression of growth compared to surgical castration in 9 and 14 month old bulls . Several other studies have also reported a more significant decrease in weight gain in banded calves compared with calves castrated surgically [24, 25]. However, a recent Canadian study found that bulls castrated with a band had a lower occurrence of undifferentiated fever and improved average daily gain and carcass weight than bulls castrated surgically . These conflicting research findings together with the results of this survey suggest that further research to compare the welfare implications of surgical and non-surgical castration methods and the optimal age of castration is needed.
In the British livestock producer survey, 90% of farmers attempted to control or prevent infection after surgical castration with 20% administering intramuscular antimicrobial prophylaxis . Thirty-nine percent of respondents reported sterilizing equipment and 2% vaccinated against tetanus. In New Zealand 16.5% of producers boiled equipment, 8.4% washed the scrotum and 4.5% used antibiotics only with surgical castration . Furthermore, only 20% of producers vaccinated calves at the time of castration. The results of the present study suggest that U.S. veterinarians are more likely to institute measures to control or prevent infection following castration than producers given the higher prevalence of disinfectant, antimicrobial and vaccine use.
Negative public perception of castration and dehorning is mounting, with increasing call for the development of practices to relieve pain and suffering in livestock . Several studies have demonstrated that local anesthesia alone or combined with systemic analgesic drug administration prior to castration mitigates physiological, neuroendocrine, and behavioral changes usually associated with pain and distress [2, 6–9, 27]. In spite of this, only 10% of New Zealand producers report using local anesthesia in calves castrated surgically . Although the use of local anesthetics at the time of castration is mandated in the United Kingdom , only 43% of British veterinarians were reported to use local anesthesia in calves older than 8 weeks of age . A recent survey of Canadian veterinarians and their use of analgesics revealed that only 6.9% of beef calves and 18.7% of dairy calves ≤ 6 months old and approximately 20% of beef calves and 33% of dairy calves >6 months old received an analgesic at the time of castration . The authors cite a lack of approved, long-acting, and cost-effective analgesics with established withdrawal times in Canada as one explanation for these findings. These results are in agreement with the findings of the present study where only 22% of respondents indicated that they routinely administer local anesthetics and only 21% indicated that they use systemic analgesics prior to castration.
Several organizations, including the National Cattlemen's Beef Association  and the American Veterinary Medical Association , have stated that pain and physiologic stress resulting from castration should be minimized. Available methods of minimizing pain and stress include application of local anesthetics and the administration of analgesics . It is significant that there currently are no analgesic drugs approved for the alleviation of pain in livestock in the United States. The FDA Center for Veterinary Medicine guidance for the development of effectiveness data for NSAIDs indicates that validated methods of pain assessment must be used for a drug to be indicated for pain relief in the target species . This requirement explains the lack of analgesic drugs approved for pain relief in livestock in the United States because there currently are no validated methods of pain assessment in food-producing animals.
A previous survey of U.S. dairy producers found that gas or electric dehorning irons were used on 67% of dairies with 67% of respondents indicating that calves were dehorned by 8 weeks of age . In contrast, beef producers in the U.S. report using saws, Barnes or keystone guillotine dehorners in almost 40% of cases with the average age of dehorning reported to be around 120 days . The results of the present survey indicate that Barnes cutting blade dehorners were preferred by veterinarians in all classes of cattle although 43% indicated that they performed disbudding with electric dehorning irons in perinatal calves. It is noteworthy that 92% of veterinarians surveyed in this report indicate that they also dehorn calves at the time of castration. This is in contrast with New Zealand producers where only 9.1% of respondents indicate that they disbud or dehorn calves at the time of castration . Several studies have examined the behavioral, physiological and neuroendocrine effects of dehorning and castration conducted separately [2, 3]. However, research into the cumulative effect of these procedures conducted concurrently is currently deficient in the published literature.