Wednesday, July 4, 2012

Preventing Abscesses

If you were naïve to farming, would you still drink milk if you observed a large, festering abscess draining in the milking parlor?  “Get the coffee mug out and catch some creamer!”  Or better yet, “We have ricotta cheese for that lasagna your wife is making for tonight.”  Picture the dairy product images.  Now think of the expressions while conjuring up images of the worst abscesses you have ever seen.  After thinking back, the image is not so healthy and wholesome is it?  Sure veterinarians receive a high level of satisfaction deflating the abscess, yelling “Fire in the hole!” before we slice into a high pressure, high volume abscess impressing wide-eyed veterinary students who end up in the line of fire.  We try to estimate the sheer amount of that foul smelling ooze and attempt to create the perfect arch to astound the client as it drains.  In fact, the image is downright disgusting, not to mention the experience has an odor that simply will not go away.  In reality, this entire mess is completely preventable with proper needle and syringe usage, medicine and vaccine storage and handling, and clean injection sites.

Abscesses are caused by damage to soft tissue and an introduction of bacteria into the wound.  Soft tissue damage results from dull needles, improper animal handling causing muscle bruising, irritating drugs and vaccines.  A bacterial infection is introduced through dirty injection sites and contaminated needles, syringes, and bottles.  In cases of blackleg, infection ensues from consumption and injection of bacteria and distribution into muscle.  As you can see, there is one common contributor – NEEDLES! 

Hold a new gleaming, clean, sharp needle in your hand and take a good look at it.  Notice the sharpness of the point.  The new, sharp needle will pierce the skin and muscle with ease, causing minimal trauma.  A dull needle will have a “barb,” a curvature, on the point.  As the dull needle punctures the skin and muscle, the soft tissue is more severely traumatized especially during withdrawal as the barb snags tissue.  Tissue remnants and dirt can remain on the barb, contaminating the medicine or vaccine bottle and transferring material into additional injection sites increasing the odds of creating an abscess.  Trace blood and tissue remnants create an additional risk by transferring blood-borne infectious agents, such as viruses, especially Bovine Leukemia Virus.  Dairymen exporting cattle or embryos to Europe can certainly appreciate that risk. 

The Needle Gold Standard is a new needle for every cow.  Keep in mind that needles are cheap.  At the very least, use one needle for every 5 cows.  Always use a new needle when changing medicine or vaccine bottles.  Try to puncture the bottle top the least amount of times as possible by using a multiple-dose syringe or a single bottle-only needle.  Even the medicine bottle top has a dulling effect on the needle.   

To further reduce tissue trauma, use the smallest needle allowed by the thickness and flow-ability of the product being injected.  To some clients, that is a tough pill to swallow.  Larger diameter needles last longer.  Plus, larger needles handle a grinder better!  Please take that as a joke.  However, in addition to minimal tissue trauma, there are distinct advantages to using a smaller diameter needle.  Ever see that dribble of medicine, particularly prostaglandin or GnRH, flow out of the injection site after the needle is removed?  If using the minimum dosage, the dribble may now place the injected dose lower than needed for optimal response.  A smaller diameter needle tends to limit this outflow of medicine.  For the drugs mentioned, a 21g needle is sufficient.  Studies have also shown that for intramuscular injection of reproductive drugs, a 1.5 inch needle is needed for adult cattle for optimal absorption. 

Contaminated syringes are also sources for abscesses.  Watch for flashes of blood and “floaters” in the syringe.  Both can be sources of injection site infection and can be sources of infectious blood-borne disease.  If anything unusual is seen in the syringe, throw it in the trash.  Cleaning syringes with disinfectants can deactivate vaccines if residual disinfectant remains in the syringe. 

If you have trouble finding a clean injection site, you have serious management problems!  Beef quality assurance recommends injections in the neck region to save the quality cuts in the rear legs.  The neck region has an additional benefit to being typically cleaner than the rear legs reducing the likelihood of infections.  Fresh cows are at greater risk for abscesses of the rear legs as a result of uterine drainage and smearing.  Therefore, please use the neck!

Do not forget about drug and vaccine storage and handling.  Prevent dirt or other contaminants from entering the medicine bottle.  Obviously, dirty needles and syringes can be sources of contamination.  A bottle with a dirty, manure covered top with numerous puncture holes is guaranteed to be contaminated.  Manage drugs and vaccines according to labeled storage and handling instructions, being especially critical of temperature and expiration dates.  Any deviation, especially for vaccines, can result in a change in composition and an increased toxin load leading to greater tissue damage. 

Pay attention to the route of administration and dosage. Intramuscular injections create the most tissue damage.  Therefore, if the drug or vaccine is also labeled for subcutaneous injection, please select the subcutaneous route.  For a large volume of drug, only inject 10ml per site to avoid serious tissue irritation.  Focusing on disease prevention which decreases use of drugs is the best approach to preventing abscesses. 

As an aside…we received a phone call from a client a month ago.  He just injected a cow with J-5.  After withdrawing the needle, the cow backed into him plunging the 18 gauge, 1.5 inch long needle deep into his thigh.  Fortunately, his thigh was free of manure and the needle was sharp; he makes a point of using single-use needles.  The client was certainly in pain, but fortunately, he did not annoy his wife with a festering thigh abscess.

Abscesses affect beef quality and are a legitimate animal welfare issue.  With more intensive management and greater dependency on injections, cattle are at greater risk for developing abscesses which can negatively impact milk production and cow health.  Fortunately, through proper needle and syringe management and strict injection site selection, abscesses are easily preventable.

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