Needlestick injuries are an inherent risk of handling needles during the course of veterinary practice. While significant effort has been expended to reduce needlestick injuries in human medicine, a relatively lax approach seems to be prevalent in veterinary medicine. It appears that needlestick injuries are very common among veterinary personnel and that serious adverse effects, while uncommon, do occur. Clients may also receive injuries in clinics during the course of animal restraint, and at home following prescription of injectable medications or fluids. Because of occupational health, personal health, and liability concerns, veterinary practices should review the measures they are taking to reduce the likelihood of needlestick injuries and develop written needlestick injury avoidance protocols.

Inadvertent puncture of the skin by a needle is termed a “needlestick injury” or “needlestick.” Needlestick injuries are an inherent risk of handling needles, and while the physical trauma of needlestick injuries is usually minor, the injuries are of concern because of the potential exposure to infectious agents and syringe contents. Concern is substantial in human medicine, where much effort has been devoted to reducing the incidence of these events. For various reasons, the same aggressive approach has not been used in veterinary medicine. While there are significant differences in the risk of needlestick injury in human and veterinary medicine, needlestick injuries in veterinary medicine should not be considered benign, and the lax attitude concerning these injuries should be replaced with a proactive attitude towards injury avoidance.

Needlestick injuries and needlestick avoidance have received much less attention in veterinary medicine. This is probably because we do not currently recognize many significant and common zoonotic bloodborne pathogens in animals in most areas and perhaps more importantly we do not currently recognize a significant bloodborne zoonotic pathogen that can be present in clinically normal animals. While people may have concern about rabies, blood contact is not considered to be a route of exposure. There is no way of knowing if we will continue to be free of substantial risk, or if a potentially devastating bloodborne zoonotic disease will emerge in the North American animal population.

Despite the absence of bloodborne pathogens such as HIV and hepatitis viruses, there are a variety of potential concerns in veterinary medicine. It is plausible that infections could occur from inoculation of bloodborne pathogens (certain arboviruses), organisms from the animal’s skin (Staphylococcus spp., Pseudomonas spp.), organisms from fine-needle aspirates (Blastomyces, Pasteurella spp., Staphylococcus spp., Streptococcus spp.) or modified live vaccines. Physical trauma can be significant, especially from large-bore needles or severe laceration that results from animal movement during injection or blood collection. Injection of substances such as vaccines, antimicrobials, chemotherapeutics, euthanasia solutions, and anesthetics also pose potential risks ranging from local irritation to systemic reactions.

There has been less study of the incidence of needlestick injuries in veterinary medicine compared with human medicine. In one study, 64% of female veterinarians reported 1 or more needle-stick injuries over their career, with vaccines accounting for 50% of the incidents. Interestingly, the reported incidence was significantly lower in large animal veterinarians (5.8/100 person-years) compared with mixed animal (9.7/100 person-years), and small animal (9.8 person-years) veterinarians. In another study, 87% of zoo veterinarians reported 1 or more needlesticks, with 6.5% of respondents requiring medical treatment for a needle-stick. Reasons for medical treatment included adverse reactions to injected agents, infections, and severe lacerations. In that study, 58% of people reporting a needlestick had been exposed to animal blood, 52% to antimicrobials, 52% to vaccines, and 17% to immobilizing agents. Similar results were reported in an Australian study, where 71% of veterinary technicians reported needlestick injuries. Two-thirds of individuals who experienced a needlestick reported injection of substances, including antimicrobials (13%), euthanasia agents (11%), sedatives (9%), vaccines (8%), and anesthetics (8%).

Overall, it is apparent that needlestick injuries are relatively common in veterinary practice. Further, anecdotal information from veterinarians and veterinary technicians suggests that these reported rates are low and likely involve significant under-reporting.

Little information is available concerning the risk factors for needlestick injuries. It is likely that veterinarians frequently engage in high-risk handling procedures. Eighty-six percent of zoo veterinarians reported recapping needles, a very high risk procedure, more than 50% of the time. A study of personnel in nonhuman primate laboratories reported that needlestick injuries occurred more frequently in people who had been employed for ≤ 2 years. There is no information available on the relative risk of different types of procedures.

While most needlestick injuries are minor, potentially serious consequences can occur. A study of female veterinarians reported adverse effects in 16% of needlesticks; however, adverse effect data must be examined critically since people experiencing adverse reactions are more likely to report having had a needlestick than others. Severe reactions included severe local inflammation, abscess formation, joint infection, localized necrosis, skin slough, local nerve damage, brucellosis, severe allergic reaction, psychedelic experience, bronchial and laryngeal spasm, and miscarriage. Anthelmintics, euthanasia agents, and anesthetics were more commonly associated with adverse effects. Accidental injection of Johne’s bacterin in a finger can result in the presence of a small nodule persisting for 4 to 6 months to painful inflammation for 24 months. Exposure to the RB51 brucellosis vaccine caused long-term (> 6 months) adverse incidents in 27% of people reporting adverse reactions, including erythema, induration, fever, chills, sweats, fatigue, myalgia, and arthalgia. Mineral oil adjuvants can produce a prolonged chronic granulomatous reaction with sterile abscess formation. A farm worker’s injection of an oil-based bovine vaccine into his finger resulted in amputation of the finger because of ischemic necrosis following increased pressure in the flexor tendon sheath. In a study of adverse effects of human exposure to tilmicosin, 61% of exposures involved inadvertent injection, with most presumed to be from needlesticks. Of the 3,168 exposures, 156 (5%) resulted in severe reactions, as designated by the presence of 1 or more of tachycardia, bradycardia, hypertension, hypotension, heart disorder, chest pain, tachypnea, or death. Thirty-six percent of those cases involved injection of ≤ 0.5 mL. Accidental injection following fine-needle aspiration is also a concern. Blastomycosis developed in a veterinarian from a needlestick following fine-needle aspiration.

The use of safety devices can reduce the incidence of needle-stick injuries. The use of protective devices has been associated with a 74% decrease in needlestick injuries during blood collection. Another study reported a decrease in injuries from 20/100,000 devices to 6/100,000 devices following introduction of various safety devices. Veterinary studies have not been reported but there is no reason why these devices would be less effective in a veterinary environment.

Cost is an obvious concern with needle safety devices, particularly when the benefits are difficult to quantify in veterinary medicine. The cost of the NSS device can be as much as 50% in certain circumstances, perhaps even more when injury treatment costs are included in the cradle-to-grave costs of sharps safety devices. Estimates on the cost to medically test and treat injured healthcare workers (in human medicine) in the United States alone range from $3 to $7 billion annually excluding unaccountable psychological trauma. Although figures specific to veterinary medicine are unavailable, it is easy to ascertain the perceived costs to a single incident.

Closely associated with the concern for the safety of those associated with the daily use of needles and other sharps is the issue of possible liability for the owner of the facility. Whether the seemingly minor injury is caused to an employee or a client, the owner of the facility may be legally responsible for the payment of damages in the event that a court were to find that inadequate safety precautions had been adopted.
Throughout North America, various jurisdictions have enacted legislation for the protection of employees in the workplace relating to occupational health. In all cases, the employee is obliged to conduct himself or herself in a cautious manner so as to avoid injury; however, the statutes universally require employers to provide a safe working environment. The failure to institute appropriate and generally accepted standards of safety protocols could result in a claim by the employee for a breach of the applicable statutory duty and give rise to investigations and sanctions by government authorities having a mandate to enforce such legislation. In the case of needlestick injuries it would be prudent for facilities owners to ensure that they are in compliance with any statutory regulations relating to the proper use, storage, and disposal of the instruments in question.

In addition to any legislative requirements, owners and employers are also required by common law principles to ensure that they are not negligent in connection with the use of needles and other sharps in a facility. The common law (essentially the precedents established by the courts over the centuries) requires that an owner or employer owes a duty of care to an employee to provide a safe working environment; the standard of care has been determined to dictate that an owner or employer must demonstrate a reasonable standard of safety having regard for other owners or employers in similar circumstances. The failure to meet the standard can give rise to a claim for damages arising from the negligent conduct of the owner or employer.

The common law duty would apply to injuries sustained by both employees and clients of the facility. In the former case, most claims would be barred by the operation of workers’ compensation legislation, which restricts the ability of an employee to sue an employer in exchange for a governmental scheme of compensation, where such legislation applies. In the latter case, clients of a facility can be injured in circumstances where they are near a needle or other sharp during the course of treatment. In a veterinary context, owners often volunteer to assist in the restraint of their animals and therefore may be exposed to unpredictable behaviors during the course of treatment. If a fractious cat attempts a spirited escape immediately before an injection, the needle can, in some cases, get misdirected and pierce the client. In such cases, it is difficult to consider a situation in which the attending veterinarian would not be liable for negligence having been responsible for the care of the animal at that time. As such, it would be prudent for a veterinary facility to adopt a policy dictating that animal owners are not to be included as part of the health providing “team” by way of assisting with restraint. If this is not possible in some cases, then it is encumbent upon the veterinary professional to properly advise the owner to be cautious.

Another area of potential liability is prescription of injectable medications or fluid therapy, such as subcutaneous fluid, for administration at home by clients. It should be considered that pet owners have no baseline knowledge of needlestick injuries, needlestick avoidance, and safe sharps handling practices. If veterinary practices dispense or prescribe injectable treatments, education regarding safe handling practices including safe administration, needle handling, and sharps disposal must be provided and documented.

Infection control has been an overlooked and under-appreciated field in veterinary medicine; however, the attitudes towards zoonotic infections and occupational injuries are changing, as is the expected level of care. Increasing information concerning zoonotic infections and occupational injuries, and publication of infection control guidelines suggests that the expected standard of care is increasing. It is prudent for veterinarians and veterinary practices to proactively address issues such as needlestick injuries for the benefit of their staff and their practice.

*Canadian Veterinary Medical Association, Dr. J. Scott Weese