Anyone in the cattle business who hasn't gotten word of the recommended site to give a cow a shot must have been asleep for the past 20 years. So, once you know the proper location to give an injection is in front of the shoulder (see graphic, page 17), the question becomes whether to give the injection subcutaneously (SQ), intravenously (IV) or in the muscle (IM).
“First and foremost, follow label directions,” answers David Thain, University of Nevada-Reno Extension veterinarian. Then, he says, set your treatment goals.
“IV treatment results in very rapid blood levels of a drug, in higher concentrations, as opposed to other routes,” Thain says. “SQ-injected medications are absorbed more slowly, reach a lower blood level and persist longer. Typically, IM injections land somewhere in the middle.”
While IV gives very rapid response, it will usually need to be repeated, Thain adds.
If a product is labeled for both IV and SQ, there's probably not much difference in overall efficacy, adds Ron Gill, Texas AgriLife Extension professor.
“You'll have quicker distribution of product throughout the circulatory system with IV compared with SQ,” Gill explains. “If given SQ, the product has to be absorbed into the bloodstream and then distributed via the blood. SQ might give a longer payout period, though, perhaps due to the slower absorption.”
Veterinarian Dan Thomson, Kansas State University, leans towards SQ administration of antimicrobials. He never recommends IV unless it's the only route of administration on the product label. Distribution patterns for the drugs given SQ or IV can vary, he says, and are often at blood levels within 4-10 hours.
Thomson agrees with others who mention worker proficiency with regard to administering a product IV vs. SQ. Consensus is that it's simply easier for most workers and vets to give an injection under the skin vs. in a vein. “With workman's compensation in mind, and the lack of difference in case fatality rate, IV is not the best option compared to SQ,” Thompson says.
He's also concerned about physical stress on animals when treating them multiple times. “In most cases, people using IV drugs treat several days in a row; this can cause tissue damage in jugular veins and surrounding tissue,” he explains. “Our research shows death loss is doubled in multiple-day treatments vs. one-time antimicrobial therapy. We think it's because of over-handling of these animals.”
Fred Hopkins, University of Tennessee veterinarian, says a product given IV will circulate through the bloodstream 2-3 hours faster than one given SQ. But, he adds, it's also true that an antibiotic begins leaving the body more quickly since it's readily available for excretion.
“Antibiotics are generally most effective when they're available above their minimum inhibitory concentration (MIC), and the level above MIC doesn't matter to the bacteria,” Hopkins says. “SQ injections will be somewhat slower to get above the MIC, but will stay above it a good deal longer.”
There are differences in reaction rate between products. Gill says many products labeled IV are given extra-label via SQ or IM, with tremendous differences in efficacy.
Mike Apley, DVM and director of the PharmCATS Bioanalytical Laboratory, Kansas State University, agrees that “time above MIC is the determining factor.”
So, quicker, higher concentrations by IV? Yes. More effective? No. “Not unless you want to hassle the animal every day,” Apley says.
Also, he doesn't like the idea of giving drugs with an IV “kicker” for a faster response.
“Putting a second drug with one of the antimicrobials and giving it IV to get a quicker response is among the most prevalent nonsense in our industry,” Apley says.
Other treatment issues
Last year, the Food and Drug Administration (FDA) banned IM use of flunixin meglumine (Banamine®); it now may only be given IV in cattle. In fact, FDA banned all extra-label use of flunixin because there were numerous cases of drug residues when it was given SQ or IM at a time when no withholding times were published.
Only a veterinarian can prescribe a drug in an extra-label manner. But, federal law limits extra-label drug use to treatment when the health of an animal is threatened, it's suffering or death may result from failure to treat. In such cases, the veterinarian must establish a substantially extended withdrawal period supported by appropriate scientific information prior to the marketing of milk, meat, eggs or other edible products to assure that violative drug residues don't occur.
For cattle, the label also restricts administration of tilmicosin (Micotil®) to SQ. IV use of this product in cattle is fatal.
The National Institute for Occupational Safety and Health (NIOSH) cautions that extreme care be used in following safe drug handling and injection procedures in order to avoid the possibility of self injection — especially with Micotil.
There's extreme hazard to humans exposed to Micotil through needlestick injuries, skin cuts, puncture wounds and contact with skin and mucous membranes. Micotil's cardio-toxic effects on the human heart can cause death. Although no antidote exists for Micotil, exposed persons should seek immediate medical intervention, as the drug's cardio-toxic effects may be reversed.
How about vaccines?
“I don't know of a vaccine with an IV label, so this discussion is with respect to drugs/medications,” Thain says.
And, one more thing…
Thain has stern advice for anyone who's been asleep for the past 20 years. “To help keep our beef wholesome, never inject a calf, cow or bull in the top butt, rump or loin muscle — regardless of age.”
Clint Peck is contributing editor and director Beef Quality Assurance, Montana State University.
Still room for improvement
The 1995 Beef Quality Audit reported 11% of beef carcasses presented for commercial processing had at least one injection-site blemish. The cost to the U.S. beef industry was an average of $7/animal harvested.
Since 1995, the industry has significantly reduced the incidence of injection lesions in both fed and cull cattle.
“Although identified as a key industry success story in the 2005 Beef Quality Audit, reduction of injection-site lesions still remains among the goals of national and state Beef Quality Assurance programs,” says Ryan Ruppert, National Cattlemen's Beef Association director of quality assurance programs.
Ways to improve your injection techniques:
Recognize that the best injection site isn't always the most convenient.
Don't use bent, dirty or broken needles.
Understand how to properly mix and administer modified-live vaccines (MLV).
Mix enough vaccine for only one hour or less.
Keep good treatment records.
Keep all injections in front of the shoulder.
Never inject more than 10cc into one site.
Don't re-inject into injection sites.
Minimize the risk of injection-site reactions.
Don't combine vaccines.
Use clean transfer needles.
Don't mix too many products.
Keep shaking the bottle.
Mark and separate syringes.
Don't use disinfectants with MLVs.
Get air out of syringes.