By Susan Himes
Texas A&M AgriLife
SAN ANGELO -- It is a brisk morning in central West Texas. Sheep are penned behind the Texas A&M AgriLife Research and Extension Service building in San Angelo. Several are run into a chute. A member of the AgriLife sheep and goat team holds a pneumatic gun. In less than 10 seconds, four rounds of vaccine have been fired off and another four ewes have been given their annual booster vaccination in preparation for lambing season.
Old problems, new solutions
An AgriLife team in San Angelo is striving to find new solutions to age-old problems. The members of the sheep and goat department of AgriLife Research and AgriLife Extension are working to find innovative ways to use technology to address the diseases, issues and concerns prevalent in the sheep and goat industry today.
Running 200 ewes through the chute and giving them each their annual CDT, or Clostridium perfringens type C and D and Clostridium tetani, booster vaccination in preparation for lambing season traditionally is cumbersome and physically taxing. Using new technology, the AgriLife team has been able to take most of the stress out of this process, for man and beast.
By utilizing a pneumatic gun to administer vaccines, vaccinating 200 ewes took less than 20 minutes, a process that would take several hours with a traditional needle system. The needle-free injection system is not only a quick, low-stress way of vaccinating sheep, it can help curb the spread of diseases that can be devastating to flocks, according to AgriLife sheep specialists.
"The pneumatic gun used to vaccinate the ewes runs on CO2," said Jake Thorne, AgriLife Extension associate. "The gun dispenses the vaccine through the animal's skin through a tiny hole seven times smaller than what is made by an 18-gauge needle. The gun has adjustable pressure, so it can be altered for use on lambs or adults, as well as for other species."
"The reason I wanted to get the pneumatic gun for the center was two-fold," said John Walker, AgriLife Research center director. "One, I think we ought to use the latest technology here so we can demonstrate it to producers and other people who may be interested in it. The other reason is to prevent disease transmission. Unless you change needles between every animal -- which people should do, but they don't -- you have the potential to transmit disease."
"Chronic diseases such as Caseous Lymphadenitis (CL) and Ovine Progressive Pneumonia (OPP) have plagued the sheep industry for decades," said Dr. Reid Redden, AgriLife Extension sheep and goat specialist. "These diseases can be spread more rapidly through a flock of sheep or herd of goats if producers don't change needles between animals."
OPP and CL
"CL is an infection of the lymph nodes and it can't be treated once they have it," Thorne said. "OPP is a viral disease that can cause various symptoms, including hardened lungs causing shortness of breath, hardened udders that don't produce milk and arthritis. You can't tell just by looking at your ewes that they have either disease. It may take years for the diseases to show their symptoms."
There are approved vaccines for CL, for both sheep and goats, but they are not widely used due to the amount of labor required to vaccinate large flocks. In the past, ranchers have been urged to cull animals that exhibit signs of CL, Redden said.
"This strategy can reduce flock or herd disease prevalence but won't eradicate the disease completely. Other more aggressive recommendations include testing all animals and culling those with positive results. This strategy can be very costly, both for testing and culling animals that would otherwise have years of productivity in their future." Redden said.
"This technology helps prevent the spread of the disease, so other vaccination and prevention methods are more likely to eliminate the disease."
CL causes internal and external abscesses. Once the boil ruptures, the bacteria-carrying pus can infect other animals.
It also can be transmitted between animals through needles or wounds.
The number of animals affected by CL or OPP vary by region, but it can be as high as 40% in the certain regions of the U.S., Thorne said.
Vaccinating safely and efficiently
The pneumatic gun can help to prevent the spread of OPP, CL and other infectious diseases, as well as serving as a faster and less labor-intensive means of vaccinating livestock. The downsides, according to Redden, are the device is limited to certain products based on the viscosity of the drug, and it is cost-prohibitive for smaller operations.
Administering vaccinations typically takes two people to make the operation run as easily and smoothly as possible. Animals must be restrained, and a needle injected. The pneumatic gun makes vaccination a task that can be easily handled by a lone individual. In addition to reducing the time and manpower needed to vaccinate, it is over so quickly that it is less stressful for the animals.
At the U.S. Department of Agriculture Agricultural Research Service's Sheep Experiment Station in Idaho, J. Bret Taylor, research leader and supervisory scientist, also utilizes pneumatic guns. Taylor and his group have worked with Walker on various research projects and studies to advance the U.S. sheep and lamb industry.
The station has always used a new needle for each animal, since eliminating a vector is one way to stop transferring blood-borne pathogens. They switched to the pneumatic gun to save time and manpower.
"When you look at the whole aspect of speed, efficiency, convenience and disease prevention, it's hard to argue against a pneumatic injector," said Taylor. "You also don't have to worry about the animal jumping around and breaking a needle off."
The only notable issue Taylor and his team have experienced with the pneumatic gun is with the vaccine freezing in the gun's line due to the chilly climate in Idaho, which regularly plunges below freezing. They remedied the problem by putting the guns inside jackets, which are battery heated to keep the vaccine in a liquid state.
Cost vs. control
With a starting price tag of around $3,000, a pneumatic gun may never be a cost-feasible replacement for syringes for smaller operations with a few head. However, Taylor said the guns are extremely durable, and based on a 2,000-ewe flock, can pay for themselves in about a decade, taking syringe and hourly labor costs into account. When considering ease of use and a drastic reduction in physical labor, Taylor was convinced that the payoff is nearly immediate.
"Needle vaccinating can be very physically taxing work," Taylor said. "With the gun, even our smallest or least physically strong team member can easily vaccinate a flock."
The pneumatic gun also eliminates "friendly fire" accidents where people accidentally get stuck by needles, he added.
The U.S. Sheep Experiment Station scientists in Idaho published a study on the effectiveness of pneumatic needle vaccines versus traditional needle vaccines on thick wool sheep. The study showed they were equally effective, therefore coat type shouldn't be a deterrent when deciding on a pneumatic system versus traditional needles.
"Pneumatic injection systems are a viable option that allows ranchers easily to vaccinate large groups of animals and drastically reduce the risk of spreading disease. It is realistic that use of vaccinations and the pneumatic system could eradicate long-standing disease from commercial-oriented Texas sheep flocks and goat herds." said Redden.