Materials and Methods

Study design—Data were collected to identify work-related injury events, consequences of those events, and identification of potential risk factors in a cross-sectional survey. The study was approved by the University of Minnesota Institutional Review Board.

Study population—Certified veterinary technicians whose certification in Minnesota was valid through the end of October 2004 and who worked as CVTs within the 12 months prior to survey administration were eligible for inclusion in the study. The CVTs were identified by use of a database maintained by the Minnesota Veterinary Medical Association; these records are routinely updated on the basis of technicians’ completion of continuing education requirements. Of 1,465 qualified CVTs, 1,427 with valid addresses were mailed a survey designed on the basis of a previous study.^6,a Respondents who indicated they had not worked as CVTs in any state during the 12 months prior to the survey were ineligible.

Data collection—Injury events that resulted from any activities (including travel) associated with the job or events that occurred in the work environment were considered work related. Intentional (assaults and self-inflicted injuries) and unintentional injuries were included among these events. Events included (but were not limited to) bites, lacerations, fractures, sprains, strains, allergic reactions, ergonomic and repetitive motion injuries, and injuries associated with exposure to radiation or anesthetic agents or incurred in motor vehicle crashes while traveling to or from a client's location as part of work responsibilities. Among these, only injuries resulting in restriction of normal activities (for any length of time), loss of consciousness, or use of medical assistance (including self-treatment), or those involving a bruise or break in the skin from a bite injury, met the study definition of an injury event.

Contact and survey administration—A 42-question survey comprising multiple-choice and open-ended questions was sent to CVTs via postal mail between April 30 and June 30, 2005. In addition to the survey instrument, a cover letter providing information about the study and informed consent was enclosed with the mailing.^a Individuals were asked to participate in the survey regardless of whether they had received a work-related injury. Up to 3 additional mailings were sent to CVTs who did not respond to the initial invitation. To encourage participation, each participant who returned a questionnaire and indicated the desire to be included in a random drawing had the opportunity to receive a retail gift card.

Survey—Participants were asked to provide responses regarding the 12 months prior to the survey completion date. Questions included whether the respondent had worked in a CVT position in the previous 12 months and during which months. Respondents were also asked for demographic and environmental information, such as duration (in years) of experience handling animals and of employment as a veterinary technician (including employment as a CVT and as an uncertified veterinary technician), year of graduation from a veterinary technician program, date of birth, marital status, annual household income, height and weight, species of animals cared for, number of hours per day and days per week worked (on average), number of veterinary staff that handled animals within their facility or department, and the types of facilities in which they worked. The survey allowed for self-reporting of the total number of work-related injury events over the 12 months prior to the survey and of descriptive information for up to 4 of these events. If the participant had incurred > 4 work-related injury events, severity was determined for the 4 most severe events (ie, those that required the most medical care or longest restriction of work or activity); descriptions were requested starting with the most severe event first. Information requested for each event included date of the occurrence, source of injury, circumstances and activities pertinent to the injury, location where the event occurred, type and anatomic location of injury, duration of associated activity restriction, amount of lost work time, and medical treatment (including self-treatment) used or received.

Data analysis—Data were analyzed to identify the frequency and characteristics of work-related injuries and to determine relevant estimates of injury rates and consequences, with the aid of statistical software.^b Poisson regression models were used to estimate injury rates by age; gender; body mass index, calculated as (weight [lb])/(height [in])² × 703; type of practice or facility; number of animal species handled during the previous 12 months; duration (in years) spent working as a CVT; duration (in years) of experience handling animals; number of hours worked per week and per day; and number of staff working at the facility. In calculating annual injury rates/100 CVTs working full-time, the numerator consisted of the total number of injury events multiplied by 200,000 full-time annual hours (40 h/wk × 50 wk/y × 100); the denominator was the total number of hours worked per year for respondents who answered the question.

Point estimates and 95% CIs were produced for each rate. Significant differences were identified among variable categories if the CIs did not overlap.

Multivariate Poisson logistic regression was used to measure associations between potential risk factors and injuries to CVTs. Directed acyclic graphs^14,15,a based on a causal model were used to identify the potential confounders to be included in the Poisson regression models for each exposure of interest. These methods identify parsimonious models and exclude covariates that should not be entered into the regression because they may introduce bias. Incidence rate ratios and 95% CIs were generated for each of the models. Significant associations between potential risk factors and injury were indicated when the CIs for the rate ratios excluded 1.0.

Results

Surveys were returned by 1,052 of 1,427 (74%) CVTs. Data from 873 (61%) individuals who indicated that they had worked as CVTs in the previous 12 months were included in the analysis; not all respondents answered every question, and proportions were based on the number of responses. Seven hundred ninety-three of the 873 (91%) respondents resided in Minnesota; 578 of 873 (66%) CVTs worked in clinics with ≥ 3 doctors, and 610 of 841 (73%) worked in clinics with ≥ 3 CVTs. Respondents reported handling the following animal types or species during the 12 months prior to the survey: dogs (834/873 [96%]), cats (798 [91%]), so-called pocket pets (eg, rabbits, rodents, or chinchillas; 646 [74%]), ferrets (423 [48%]), avian pets (397 [45%]), exotics (eg, snakes, turtles, or lizards; 242 [28%]), horses (150 [17%]), pigs (144 [16%]), sheep (130 [15%]), goats (124 [14%]), cattle (119 [14%]), poultry (91 [10%]), monkeys or other primates (44 [5%]), zoo animals (36 [4%]), and other (43 [5%]). Of 873 CVTs, 862 (99%) had graduated from a CVT program, and 793 (91%) worked in Minnesota during the study period.

Respondents reported their household income levels as follows: < $15,000 (29/838 [3%]), $15,000 to < $20,000 (43 [5%]), $20,000 to < $25,000 (112 [13%]), $25,000 to < $35,000 (143 [17%]), $35,000 to < $50,000 (155 [18%]), $50,000 to < $75,000 (208 [25%]), and ≥ $75,000 (128 [15%]). Twenty (2%) respondents indicated they were unsure. Four hundred eighty-one of 868 (55%) respondents were married, 294 (34%) had never married, 47 (5%) were living as if married or had a domestic partner, 39 (4%) were divorced, and 7 (1%) were separated or widowed.

A total of 1,827 work-related injury events were reported for the 12 months prior to survey completion, with 465 of 873(53%) CVTs who answered the question reporting ≥ 1 injury event. The total number of hours worked during the year, reported by 861 respondents, was 1,543,203.2. The overall injury rate calculated on the basis of these values was 236.8/100 persons/y. Characteristics of CVTs who did or did not incur an injury were summarized, and injury rates were calculated on the basis of exposure frequencies (Tables 1 and 2).

Injury rates increased significantly with increasing numbers of animal species handled and number of staff handling animals in the respondents’ facilities. The injury rate for CVTs with < 6 years of experience handling animals was significantly higher than that for those with 6 to 9, > 9 to 14, or > 14 years of experience. The injury rate for CVTs ≤ 26 years of age was significantly higher than that for any age group > 26 years. The rate was significantly higher for individuals who graduated from a CVT training program ≤ 3 years before survey completion than for those who graduated > 3 to 6, > 6 to 12, or > 12 years before that time, and the rate was significantly lower for respondents who graduated > 12 years before completing the survey, compared with those who graduated at earlier time points. Individuals who worked or volunteered as CVTs for ≤ 3 years had significantly higher injury rates than did those who performed these tasks for any period > 6 years. Substantial variation in injury rates was noted among the different types of veterinary facilities. Respondents in mixed mostly small animal practices had a significantly higher rate of injury, compared with respondents in any other facility types.

Six hundred of the 1,827 (33%) injury events were bite related, and 353 CVTs reported ≥ 1 bite injury event. Rates of bite injuries were summarized according to CVT characteristics (Table 3). Similar to overall injury findings, the bite injury rate was significantly higher for respondents ≤ 26 years of age than for other age groups. Those who had worked as CVTs for periods > 6 to 11 years had significantly lower bite injury rates, compared with rates for respondents who had done this work < 3 years. The rate was significantly higher for those who believed work-related injuries could not be prevented, compared with those who believed that these injuries were preventable or indicated they were unsure, and the highest rate was reported for respondents who believed that some, but not all, injuries could be prevented.

Of the 1,827 total injury events, 777 reported as the most severe events were described by CVTs. Among these, the most commonly reported injury types were bites (402/777 [52%]); cuts, lacerations, or scratches (238 [31%]); and bruises or contusions (174 [22%]). Primary anatomic regions involved the hands (including digits; 433/777 [56%]) and arms (including elbows or wrists; 230 [30%]). These injuries were most frequently received from cats (365/777 [47%]) and dogs (274 [35%]). Clinic treatment areas (368/777 [47%]) and examination rooms (143 [18%]) were the most common locations where injuries occurred, and the activities that most frequently resulted in CVT injury were animal restraint (421 [54%]) and treatment (157 [20%]). Of the 777 most severe injuries, 72 (9%) were attributed to lifting animals or objects; 6 of 777 (0.8%) injury events resulted in hospitalization and 104 (13%) resulted in lost work time.

Respondents reported sources of treatment for their injuries as follows: self-managed (366/742 [49%]), physician (149 [20%]), urgent care (73 [10%]), chiropractor (36 [5%]), nurse (26 [4%]), colleague (19 [3%]), physical or occupational therapist (13 [2%]), other (10 [1%]), and no treatment sought (174 [23%]). More than 1 treatment source could have been reported for each injury. Several of these injuries resulted in restriction of normal activities, with 139 of 777 (18%) respondents reporting work restriction for ≥ 1 day and 187 (24%) reporting work restrictions of any amount of time; 72 (9%) reported persistent problems at the time of the survey. Oral reports were made to a supervisor or management for 440 of 777 (57%) most severe injuries; reports for 87 (11%) injuries were submitted in writing; reports for 77 (10%) were given both orally and in writing; and 173 (22%) were not reported. For injuries that were not reported to a supervisor or management, reasons given were as follows (> 1 reason may have been given for each injury): the CVT considered the injury to be a minor incident (128/173 [74%]) or part of the job (26 [15%]); they had been too busy (14 [8%]) or it was unnecessary to report the injury (8 [5%]); the injury resolved itself (8 [5%]); or the injury happened over time or the individual was not immediately aware of it (7 [4%]). Some CVTs did not report an injury because they considered it their own fault (6/173 [3%]), they were still able to work (5 [3%]), no management was present (3 [2%]), the CVT was the manager (3 [2%]), or they were not aware there was a system to report events (2 [1%]); 10 (6%) CVTs did not report an injury for other reasons. No explanation was given for lack of reporting for 4 (2%) of the injuries.

Results of multivariate modeling of several exposures of interest were summarized for all injuries (Table 4). Risk of injury was significantly higher for CVTs who handled 4 or 5, 6, or > 6 species during the year, compared with that for CVTs who handled < 4 species in that time. Although < 6 years of experience handling animals appeared to be associated with a slightly higher risk of injury, compared with > 14 years of experience, the finding was nonsignificant. Having ≥ 6 to 9 years and having > 9 to 14 years of experience were each significantly associated with a slightly lower risk of injury, compared with the referent category of > 14 years. A significantly higher injury risk was associated with working in small animal and mixed mostly small animal facilities, compared with college or university facilities, whereas a significantly lower risk was associated with working in mixed large and small animal (described as having a 50:50 ratio), government or regulatory, or commercial or industry facilities. Analyses pertinent to number of hours worked identified a significantly lower risk of injury for CVTs working < 40 h/wk, compared with those working ≥ 40 h/wk. Finally, significantly higher risks of injury were found for those indicating belief that some or all work-related injuries cannot be prevented, compared with those who believed that such injuries are preventable.

Discussion

The study described here enabled identification of the frequency, consequences, and potential risk factors for work-related injuries among veterinary technicians certified in Minnesota. Owing to differences in study methods, populations, and definitions of injuries, results of previous studies could not be directly compared with these results. Prior studies focused either specifically on veterinarians or on combined data for veterinarians and other staff members. For example, in 1975, Thigpen and Dorn¹ analyzed data from the AVMA Group Insurance Trust and reported a mean work-related injury rate of 22.7/1,000 insured veterinarians/y. More recently, Nienhaus et al¹³ studied insurance claims data for German veterinarians and their staff, on the basis of an equivalent of the US Worker's Compensation insurance, and reported an annual incidence rate for work-related injuries of 10 injuries/100 veterinarians and staff working full-time. Because these injuries would be expected to include only those that resulted in > 3 days of lost work time, less severe injuries were likely not included in that analysis, resulting in an underestimation of injury rates. In the present study, the injury rate identified for CVTs (236.8/100 persons/y) was similar to the rate identified for veterinarians by Thigpen and Dorn.¹

Another potential source of differences among studies is that 848 of 872 (97%) respondents in the present study were female. In contrast, investigators in previous studies^2,6,11,16 on injury that included veterinarians reported lower percentages of female than male participants.

Most (687/781 [88%]) of the CVTs in this study worked in clinics or departments where ≥ 6 employees handled animals. Injury rates were highest for those in large clinics or departments, on the basis of the number of staff; CVTs working in locations with > 13 veterinary staff members who handled animals had significantly higher rates of injury than those whose groups included < 13 staff members handling animals. Significantly lower rates were identified for total injuries and injuries from bites among CVTs who worked at facilities or in departments with < 6 staff members who handled animals, compared with those whose groups included 6 or more individuals performing these tasks; this finding may have been associated with a smaller number of animals seen at departments or clinics with fewer staff members. A higher injury rate in large clinics or departments may also be related to the complexity of procedures performed and communication limitations among large numbers of staff.

Of CVTs included in the present study, 592 of 873 (68%) worked in clinics treating small animals. A descriptive study¹² of a convenience sample of attendees at an Australian veterinary nurses’ conference found that 122 of 147 (83%) veterinary nurses worked in small animal clinics. On the basis of multivariate modeling results, working in small animal clinics, compared with college or university facilities, was associated with a significantly higher risk of injury for CVTs in the present study. Compared with college or university facilities, a significantly higher risk of injury was also found for CVTs working in mixed mostly small animal clinics, which may involve working with a greater number of animal species or types and therefore increased potential for injury. Although not explored in this study, the CVTs who worked in college or university facilities may also have been working primarily with small animals; thus, differences in risk may be related to factors such as management practices or training and oversight. Nienhaus et al¹³ previously described a slightly higher risk of injuries to veterinary staff in large versus small animal practices; however, adequate data were not provided, and as previously mentioned, the injury types were unlikely to be directly comparable to those of the present study because data were obtained from a compensation claim–related database.

Consistent with previous reports for veterinarians treating small animals, cats and dogs were reported most frequently as the sources of injury in this study. According to Nienhaus et al,¹³ animals were the most frequent cause of occupational injury insurance claims (304/459 [66%]) by veterinarians and their staff, with cats and dogs the source of most animal-related injuries in practices that treated small animals; horses and cows were the most common injury sources in practices that treated large animals. These findings are also consistent with studies^1,2,6 of injuries incurred by veterinarians. In our study, dogs were the most commonly handled species, but the highest proportion of the self-reported most severe injuries were received from cats.

Results of multivariate modeling indicated that personnel working < 40 h/wk had a significantly lower risk of injury than did those who worked ≥ 40 h/wk. This may be a consequence of higher levels of fatigue in CVTs who have long work weeks. This model did not include the number of animals handled and therefore did not take into account any differences in the frequency of work-related exposure to animals during the work week.

Although we were unable to directly compare these results with those from previous studies, some findings appeared similar. As in the present study, higher rates of occupational injury have been found among younger age groups in veterinary settings^1,6; Gabel and Gerberich⁶ reported a higher risk of work-related injuries for veterinarians < 36 years of age, compared with older age groups. However, the youngest age group (24 to 35 years) for veterinarians in those studies included older individuals than did the youngest CVT group in our study (≤ 26 years), possibly because of the length of time required to complete a degree in veterinary medicine. Consistent with findings from a study² indicating that veterinarians perceived their occupation to be dangerous, more than half of the CVTs in the present study (437/856) believed work-related injuries were a problem for veterinary technicians. Multivariate modeling revealed that the association between believing injuries are a problem and the risk of injury was significant, even when controlling for facility type and number of years’ experience as a CVT.

In the present study, the greatest proportion of work-related injuries described as the most severe by CVTs were to the hands and arms (663/777 [85%]), and this also appeared similar to findings in previous veterinary studies.^11,13,16 The finding that bites were the most frequently reported type of injury in the present study (402/777 [52%]) was also not surprising. In a study by Poole et al,⁸ cat and dog bites were among the most common injuries to veterinarians and other veterinary staff members. Jeyaretnam et al¹⁰ found that dog and cat bites were an important source of physical injuries for veterinarians and accounted for the largest number of workdays lost during a 12-month period. In another study,³ cat bites were the primary injury in 583 of 1,080 (54%) reported workers’ compensation claims from veterinary practices in 1996. Nienhaus et al¹³ also reported that the most frequent injuries that German veterinarians received from animals were bites and scratches. A study by van Soest and Fritschi¹² found that 98% of the reported injuries during veterinary nurses’ careers were due to bites and scratches, and in a study¹⁷ of Canadian veterinarians, 586 of 806 (73%) respondents had incurred injuries from bites and scratches during the previous 5 years. Similarly, Lucas et al¹⁶ reported that bites were one of the primary sources of injury during veterinarians’ careers.

More than half of the respondents in the study¹² of Australian veterinary nurses (77/147) indicated they had chronic back and neck pain over their careers, and 34 of 77 (44%) reported lifting as the most frequent cause of this pain. In the present study, 72 of 777 (9%) of the most severe injuries reported in the 12 months prior to survey completion were attributed to lifting animals or objects, and 72 (9%) CVTs reported they were still having persistent problems at the time of the survey as a result of an injury, consistent with findings from a study⁸ of veterinarians and staff.

In contrast to findings in another study,² the proportion of injuries in the present study that resulted in hospitalization was small (6/777 [0.8%] vs 30/177 [17%]). However, most animals handled in the earlier study² were cattle and horses, and it might be expected that injuries incurred from large animal species could result in hospitalization more often than those received from small animals. In a study¹⁶ of Australian veterinarians, 356 of 2,188 (16%) required hospitalization at least once during their careers. In the present study, some CVTs sought treatment for injuries from healthcare providers, but 540 of 777 reported either having no treatment or providing self-treatment for their most severe injuries. In other studies, 23%¹⁶ to 77%² of veterinarians were reported to have self-treated injuries during their careers. Also consistent with studies of injuries to veterinarians,^1,2,14,17 104 of 777 (13%) CVTs in the present study reported lost work time, and 187 (24%) reported having work restrictions attributed to their injuries.

Limitations of the present study should be considered when the findings are evaluated. First, it was not possible to assess the impact of the lack of information from nonresponders. This may limit generalizability if the nonrespondents were different with respect to factors such as type of practice, work practices, and experience. However, we consider that the respondents likely represent the spectrum of working CVTs, considering that the response rate was 1,052 of 1,427 (74%). The possibility remains that the findings from this study may not be generalizable to populations of CVTs in other states. Potential biases may have resulted from the use of self-reported surveys for injuries and relevant exposures; however, numerous strategies were used to minimize recall bias, including limiting recall of injury events to the previous 12 months, an approach used successfully in a prior study⁶ of injuries to veterinarians. Finally, given that some individuals working in veterinary clinics may not be CVTs, the results may not apply to all technicians. It is likely that the CVTs perform more complicated procedures but may also receive more training in animal handling than do noncertified workers. The extent of this potential bias is unknown.

The magnitude of the work-related injury problem and potential risk factors in a population of CVTs were identified in the present study. This study serves as the foundation for future analytic studies that can identify specific risk factors for injuries and may serve as a basis for development of appropriate prevention and control efforts. Future studies might explore whether changes in the work-related factors have an impact on the risk of work-related injuries to CVTs over time.