Monday, December 31, 2012

Dexamethasone and EHD in Whitetails

I’ve spent many hours researching Dexamethasone over the last couple of years.  Most of my time involved the search for how dex might benefit us in the deer industry with EHD.  Please consult your veterinarian before trying any of the following drugs and dosages.  Also note that using Dexamethasone in pregnant does can cause abortions.  In pregnant does, a small dose of 0.25 ml of Banamine may be a better choice.  I’d personally prefer to lose the fawns and save the doe with dex than take a chance on losing the doe and fawns by not using dex.

EHD, short for Epizootic Hemorrhagic Disease, is a viral disease that infects certain animals including white-tailed deer.  The virus causes inflammation, swelling, fever, internal hemorrhage and significant damage that can result in serious secondary infections.  The virus often results in death. 

Like many in the industry, my protocol was Draxxin and Banamine.  The year 2011 was a very bad EHD year.  What we saw in many of the deer that died in Texas and other states was considerable GI tract damage.  Banamine is irritating to the GI tract so it is no longer the drug of choice for the fever and inflammation caused by EHD because it exacerbates the damage.  Dexamethasone has similar effectiveness for reducing fever and inflammation.  Dexamethasone is a synthetic glucocorticoid which is produced normally in the body.  As a steroid, it has other advantages over Banamine.

My wife, Annette, is an asthmatic.  She has taken dex for severe asthma.  I started researching human uses of dex.  If an asthmatic has a viral infection in the lungs, dex is given because it has been shown to stop the virus from replicating.  I’ve found numerous articles that stated this fact.  EHD is a different virus but I was intrigued with the possibility that dex may work for it.  Dex has also been used to stop brain hemorrhage.  Since EHD is a hemorrhagic disease causing internal hemorrhage, it made sense to me that it might be beneficial.

The problem with using dex is that the concentration (mg/ml) is low and giving a dose to a grown deer takes a large volume.  I discussed dosage problems with my veterinarian and asked him if it could be compounded to a stronger concentration.  He checked and let me know that it could be.  Most dex that veterinarians carry is either 2 mg/ml or 4 mg/ml and is either in a propylene glycol or sodium phosphate base.  The dex sodium phosphate (Dex SP) acts quicker but lasts less time than the propylene glycol.  Dex SP is easier to concentrate.

I chose to use dex SP at a 12 mg/ml concentration.  I wanted a strength that I could use in a 2cc dart for remote delivery.  The SP is also thinner so delivery in a dart is easier.  I experimented with different combinations and strengths.  My veterinarian is very good about working with me to try something new when standard protocols don’t work.  I used dex in combination with different antibiotics like Draxxin, Exceed, Baytril and Nuflor.  My vet recommended using an antibiotic with the dex since dex is an immunosuppressant.  The general opinion is that since dex suppresses the immune system, an antibiotic should be given with it as a prophylactic to prevent infections.

I used about 80 darts for drug delivery during the EHD season of 2012.  My veterinarian initially suggested a decreasing dose program for dex.  I started by using 12 mg dex on day one then cutting the dose in half for the next 3 days.  12 mg on day 1, 6 mg on day 2, 3 mg on day 3 and 1.5 mg on day 4.  I gave antibiotics on day 1 and followed up if needed on day 4.  After many combinations, I finally found the best success was using a single 48 mg dose of dex SP without the use of antibiotics.  The following is why I think I was experiencing success with that final dosage. 

Smaller doses of dex will control fever and inflammation in general.  I wasn’t having success at the lower doses so I continued increasing them.  Even when I started using an initial 48 mg dose, decreasing over the next 3 days and combining this with antibiotics, I was having some success but not enough to satisfy me.  The single 48 mg dose without antibiotics worked best.  High doses may last longer and decrease more gradually than multi-day doses.  For instance, Baytril used for cattle calls for a multi-day dose of 1.1-2.3 ml/100 lb daily for 3 days.  A single dose of 3.4-5.7 ml/100 lb can be used instead of multi-day doses.  By using the higher dosage it takes longer to metabolize the drug and therefore stays in the body longer.

I believe that the higher dose finally was enough to stop the virus from growing as found in asthmatics.  The success may also be due to the immunosuppressive quality of the dex.  I had been trying to counteract the immunosuppression of the immune system caused by dex by giving prophylactic antibiotics.  I had also been giving decreasing dosages over a total of 4 days to gradually reduce the amount being used and wean the animal off more slowly.  Then I learned about the effects of an overactive immune system.

Cytokines are present in a normal animal’s body.  They are triggered by an antigen like a virus to send immune cells to the site of infection.  One problem with an antigen like the EHD virus is that it can cause an over responsive action of the cytokines known as a cytokine storm.  In a cytokine storm, an overabundance of immune cells is sent to fight the infection resulting in normal healthy cells being destroyed.  The immune system is actually killing the animal.  In the case of pneumonia, a cytokine storm can send so many immune cells to the lungs that it can actually cause the animal to die of suffocation. 

I believe, without the scientific evidence of EHD in deer to back me up, that Dexamethasone works.  The dex stops the virus and/or suppresses an overactive immune system.  We need more scientific research but without it we have to be innovative in searching for new ways to fight the disease until a vaccine or other solution is found.  I’ve talked to people all over the nation suggesting they try the high dose of dex and the ones who tried it had good results also.  Not all vets are open-minded.  Someone in Oklahoma told me his vet wouldn’t even order the strong concentration of dex for him.  If we’re losing large numbers of animals with current therapies, we must try something different.  I hope that this long description of my results using Dexamethasone therapy for EHD in white-tailed deer helps others.  I’ll remain open-minded as well.  We need to continue to share information so that we can all learn from each other’s experience.

Charles DeerMan Black

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