Needle-Free Injection Technology

How Needle-Free Injection Works

Needle-free injection devices place liquid under pressure and expel the liquid through a microscopic orifice. As the liquid passes through this orifice, the liquid forms a narrow jet injection stream that penetrates the skin and delivers the liquid into the animal’s tissue. The injection occurs within a fraction of a second.

The device settings typically control the delivery depth so that the medication or vaccine can be delivered into the intradermal, subcutaneous or intramuscular tissue. Intramuscular delivery is most common, although some needle-free devices are specifically engineered to deliver a small dose of vaccine into intradermal tissue. The dose volume may be either fixed or adjustable, depending on the type of device. Some needle-free devices can inject large animals such as finishers, sows, and boars, while other needle-free devices are specifically designed to inject younger pigs. Because all liquid injectable products can be delivered with needle-free devices, some producers that utilize the needle-free technology have removed all use of needles on farm.

Needle-free devices require a power source to appropriately place the liquid under pressure and propel the liquid into the animal tissue. The power source may be pneumatic (compressed air or carbon dioxide) or electric (a rechargeable battery compresses a spring). Pneumatic devices are the most commonly used needle-free devices on U.S. farms.

When implementing needle-free technology, it is important to plan for what power source will be utilized to make sure it is compatible for the location in the barn in which you will be giving different injections. For piglet processing injections on the sow farm, the device may be placed on a processing cart that is used in the farrowing rooms. To inject nursery pigs, finishers or sows, you will want a more portable device that allows the worker to move from location to location.

Vaccine Efficacy

Needle-free delivery exposes vaccines to a broad portion of the animal’s tissue. When giving an intramuscular needle-free injection, some of the vaccine will be left in the shallower (intradermal and subcutaneous) tissue layer containing dendritic cells that help generate a strong immune response. Some needle-free devices seek to target only the intradermal tissue layer, often at a lower dose volume.

Needle-free has been studied with many swine vaccines and the immune response has been shown to be equivalent or superior to conventional syringes (Pandya et al., 2012). 

Food Safety

While it is rare for broken needles to occur, their occurrence creates risk for pigs, consumers, producers, the packing plant, and the pork industry as a whole. Current prevention methods to exclude broken needles from the food supply can be problematic in execution as early detection of bent needles that are likely to break can be difficult.  Packing plants encourage reporting of an incidence of a broken needle, but the incident may not always be reported. At the packing plant, broken needles may be detected, but the size, material of the needle, and its position within the tissues may impact this detection. Although uncommon, consumer needle incidents do occur.

Broken needles in meat are a concern for all markets, but valuable U.S. export markets are especially sensitive to these risks. As our international customers view U.S. pork as being produced to the highest quality standards, a broken needle incident could harm this brand and impair the premiums paid for our pork.

Needle-free technologies represent a vital compliance tool to protect the industry from liability and negative publicity of production practices. It also gives producers an opportunity to promote the use of technology to advance food safety within their supply chain.

Worker Safety

Needle-free devices eliminate the risk of inadvertent needle-sticks and most have advanced safety features to reduce the risk of accidental self-injection. Because needle-free devices do not require the worker to manually squeeze a handle to deliver an injection, there are also improved ergonomics and reduced repetitive motion injuries among employees. 

It is important to remember that needle-free devices do not completely eliminate the risk of accidental self-injection. Workers are advised to always point the device in a safe direction and take their time when giving injections. Personal protective equipment is recommended, but needle-free injections can still penetrate most clothing and gloves.

Preventing Cross-Contamination

Re-using needles has been shown to spread porcine reproductive and respiratory syndrome (PRRS) and other diseases from one pig to the next (Baker et al., 2012). Disease transmission becomes an even greater problem when farms, due to time and labor constraints, inject a large number of animals with the same needle. While policies for “one-needle-per-sow” or “one-needle-per-litter” seek to control disease transmission risks, this is difficult to manage and compliance with such policies is often not achieved.

Needle-free drastically reduces the incidence of disease cross-contamination, because there is no invasive needle to carry blood and other contaminants between animals (Baker et al.,2012).

How Producers Assess the Cost-Benefit of Needle-Free

Producers are advised to consider their veterinary protocols when assessing the cost-benefit of needle-free, to make sure that ancillary costs like disease transmission or injection quality are considered in the analysis of needle-free. Oftentimes needle-free is actually lower in cost when needle-changing protocols and other reasonable factors are considered.

Producers often implement needle-free where they will get the “most bang for their buck” and this leads them to implementation at the sow farm. The majority of piglet injections will be given on the sow farm, allowing the producer to provide a large number of injections with a concentrated number of needle-free devices. Additionally, some models of needle-free devices have the ability to be used on both piglets and sows, allowing even more injections-per-device. In the nursery and finisher phases, the direct cost of needle-free is often higher because of the lower number of animals per site and the lower number of injections being given. Adoption in nursery-finish operations are often linked to the food safety value of the technology and producers’ adoption of a “no needles ever” production program.