The idea of delivering an injection without the use of a needle may seem preposterous. However, the use of needle-free injections has actually been around since the 1930s and has successfully been used in humans since its introduction.
It has only been recently that needle-free injection has been adapted for on-farm use. This technology has been slow to gain a foothold because needle-syringe injections are fairly inexpensive and easy to use.
The start-up cost of the equipment — which ranges from $2,500 to $3,000 — gas-storage infrastructure (for systems using compressed air, carbon dioxide or nitrogen), operator training and maintenance of the units may be discouraging to some.
Yet, there are many benefits to needle-free injection. Here is a look at the potential advantages this technology has to offer.
Reduces disease transmission
Needle-free injection greatly reduces the risk of transmitting bovine leukosis, anaplasmosis, bovine viral diarrhea and other blood-borne diseases that can be transferred from one animal to the next through contaminated needles.
Re-use of needles is a common practice on dairies in the U.S. According to the 2007 National Animal Health Monitoring Study (NAHMS) for dairy, only one out of seven operations used a new needle for each injection. The majority of operations used each needle to give two to 10 injections.
Needle re-use is considered a major method of transmission of bovine leukosis virus (BLV) in cattle. The 2007 NAHMS study results showed that 83.9 percent of U.S. dairy operations were positive for BLV.
A research trial conducted in 2007 Kansas State University compared the transmission of Anaplasma marginale infection with needle-free and standard needle-syringe injection. Results indicated that the blood-borne parasite Anaplasma marginale was not transmitted by a needle-free injection device, while conventional needle-syringe use did result in transmission in some animals.
Eliminating the possibility of transferring diseases between animals was the driving force behind the adoption of needle-free injections for Pete DeHaan Holsteins, a 2,250-cow operation in Salem, Ore. “We made the switch to needle-free injection four years ago, but before that our protocol was single needle-syringe, single cow,” says Pete DeHaan, owner. “We’ve eliminated cross-transfer of diseases between animals by a needle.”
DeHaan says needle-free technology also fits in with his dairy’s philosophy of treating each cow as an individual. “You wouldn’t want to receive an injection at your doctor’s office that was used on the person there before you, would you?” asks DeHaan.
Research indicates that there are immunological advantages to needle-free injection, as the vaccine is evenly distributed into the body, which enhances cellular contact and product efficacy.
Traditional needle and syringe administration results in a pocket or bolus forming in the tissue adjacent to the tip of the needle. The needle-free injection improves the dispersion of the vaccine throughout the tissue. As the vaccine forces its way through the tissue, it follows the path of least resistance, resulting in a widely dispersed, spider-web-like distribution, says Scanlon Daniels, veterinarian with Circle H Headquarters, LLC in Dalhart, Texas. This wide dispersion of vaccine is thought to increase exposure of the antigen to specialized antigen-presenting cells; thereby resulting in an enhanced immune response.
Several studies, in numerous species, have demonstrated that needle-free vaccine delivery results in an enhanced immune response when compared to traditional needle and syringe vaccine delivery.
Two studies specific to dairy and beef cattle published in the June 2005 issue of The Bovine Practitioner demonstrated a greater immune response to some antigens when administered with a needle-free injection device versus needle and syringe.
Improve beef quality
It is unknown how often needles break off in the animal, but it does happen, says Daniels. This is a big food-safety issue, as broken needles can migrate into the tissue and, if not immediately handled, are impossible to find.
The possibility of needle fragments and broken needles finding their way into the food system is a food-safety issue.
Another meat-quality issue is injection-site lesions. The information regarding injection-site lesions and needle-free is contradictory. Anecdotally, injection-site lesions are believed to be reduced with needle-free injection because it creates an entry point about one-seventh the size of an 18-gauge needle. This small entry point could help to avoid tearing in the injection site, which can create avenues for the development of scar tissue within the valuable muscle tissue, says Ed Stevens, chief executive officer for Pulse Needle-Free Systems in Lenexa, Kan.
Research regarding injection-site lesions is inconclusive. A study performed in 2009 at Kansas State University comparing injection-site lesions in swine found more injection-site lesions with needle-free injection than needle-syringe. Another study done at Iowa State University in 2004, also done with pigs, found no difference in abscess formation between needle-free and conventional needle injection.
More research specific to injection-site lesions is needed.
Accidental needle-sticks in human health-care workers are estimated to occur five out of 100 times worldwide. The number of needle-sticks associated with dairy workers is unknown, but the risk of an accidental needle-stick is eliminated with a needle-free device.
It is still possible to inject oneself with a needle-free device; however, manufacturers indicate that needle-free devices come with multiple safety features to prevent that from occurring.
The issue of pain management and animal welfare are areas that are under increased scrutiny.
Although there is no research to prove that stress levels and pain associated with needle sticks is reduced in animals, the lack of a needle would suggest that pain and suffering is reduced. Research indicates in humans needle-free injections cause less pain and stress at the time of vaccination than needle-syringe devices, although there have been complaints of post-vaccination pain.
The benefits of this technology appear to outweigh its disadvantages, but we will have to wait for the science to catch up with the technology to be sure.
How it works
Needle-free injections use compressed air, carbon dioxide, or nitrogen and a variable pressure pneumatic amplifier to push an injection into the body. A dose of medication is propelled at a high velocity directly through the skin and into the subcutaneous or intramuscular layer of tissue in a fraction of a second.
The needle-free injector has to be perpendicular to the animal’s skin for it to work. There are three steps involved in needle-free delivery:
Step 1. Apply the device to the skin. (Most devices are pressure-activated.)
Step 2. Give the injection. (Keep the device firm to the skin so that it does not move.)
Step 3. Pull device away from the target.
The needle-free device comes with a pressure gauge to ensure the pressure is consistent with each administration. This ensures that each animal is vaccinated at the proper tissue depth and with the exact dose of medicine. This is not the case with needle-syringe administration of vaccine, which is equipment (needle length and gauge) and technique dependent, says Scanlon Daniels, veterinarian with Circle H Headquarters LLC in Dalhart, Texas.
The power source is carried in a backpack by the person giving the injections. The backpack weighs approximately 12 pounds. The needle-free system is recharged in approximately 1.5 seconds. (The power source, weight and operating parameters will vary by device.)
Another potential benefit to a needle-free system is to integrate it with a dairy operation’s radio-frequency identification (RFID) system. “By incorporating RFID and needle-free, you would create a fully traceable system,” explains Daniels. “I don’t know of anyone doing this yet, but the possibility is there.”
Which vaccines work?
For the most part, all injectible liquids can be used with a needle-free device. Some suspensions may be problematic in some devices.
Consult with your veterinarian and animal-health company representative to determine which vaccines and medications will work best for your system. As with needle injections, people who are sensitive to certain medications should not handle these products through a needle-free injection device.