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Why doesn’t my horses CRP go down?

Animals that respond to health challenges activate both innate and acquired immunity.  The innate immune system is not dependent on specific responses (as is antibody response) but stimulates many aspects of the host’s processes. In addition to many responses (such as fever, increased white blood cell count and more) the liver is recruited to produce acute-phase proteins.   Acute phase reactions are highly regulated.  There is a maximum serum concentration within one to two days and a decline with recovery from the infection.  Feedback regulatory pathways limit the response and these proteins decline in 4-7 days after the stimulus is gone.  When the receptors that trigger the production of acute phase reactions continues, the cycle becomes chronic.

C-reactive protein is an acute phase protein that is used as a diagnostic tool. Measuring and charting CRP values can prove useful in determining disease progress of the effectiveness of treatments. There is little published information about CRP values in horses and relating these values to disease.  We would like to determine why some horses that we follow are clinically well but continue to have a high CRP.  One possibility is intestinal parasites.  Recently we looked at the presence of parasites in  a group of horses, all were given a single dose of moxidectin gel. The horses were examined 42 days after deworming.  All the horses had intraluminal and encysted parasites,bots and tapeworms.  Is it possible that these parasites are associated with a chronically elevated CRP in some horses?


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The CRP values in these horses ranged from 0 to 59 micrograms/ml.

We would like to associate parasite load (measured by fecal egg counts or FEC) with CRP levels.  If we look at fecal egg count reduction as a measure of treatment effectiveness and CRP we may generate some good data. This is where you come in.  If you have a horse that has high fecal egg counts (greater than 500 eggs/gram) we would like to treat the horse and then measure the FEC after treatment.  To determine the feasibility of running a GLP study (the expensive one) we want to survey some horses, 10 or so.  We would do fecal egg counts, treat, and run the count again after treatment.  We will run the FEC at no charge for the 10 horses that can participate in this program.  To qualify the initial determination that the horse has a high FEC must be known, you’ll have some of that data recorded already.  We will confirm that and then enroll the horse.  Contact us by email to determine if the horse will qualify and we can let you know how the study will be conducted. This study will be randomized and placebo controlled.  You need to understand what a placebo is and how it may affect your decision to participate in our program.