Laminitis and the symptoms commonly related to IR (cresty neck, easy keeper, fat pads, etc.) may lead one to believe that their horse may very well be IR, but those symptoms do not have predictive value in themselves. Blood work is the only true predictor of IR and is very important in determining where a horse lies on the “IR Progression Curve”. It is relevant for determining many other health consequences (biliary obstruction – a colic risk, Malabsorption Syndrome, depleted immune system, etc.) that may be present in your horse as well. http://www.forloveofthehorse.com/taketheguesswork.php This article, written by Dr. Thomas, will explain the importance of having the correct blood work performed on your horse.
The specific tests that you have done are important. ACTH is simply not enough and I will get into this in a later blog. Too often, too few tests are performed. These specific tests will show everything that is going on inside of your horse: Alkaline Phosphatase, AST, ALT, GGT, CK, LDH, Cholesterol, Triglycerides, Total Protein, Albumin, Globulin, Total Bilirubin, Direct Bilirubin, BUN, Creatinine, Glucose, Calcium, Phosphorus, TCO2 (Bicarbonate), Chloride, Potassium, Sodium, a Comprehensive CBC with Differential, and Serum Insulin. To read a “brief lesson in blood chemistry”, read A Lesson In Blood Chemistry Analysis: http://www.forloveofthehorse.com/blood_chemistry_analysis.php. This is another well written article by Dr. Thomas.
Also, just as importantly, when your vet draws the blood, it is extremely important that the blood is spun in a centrifuge within 4 hours of the draw. This involves the separation of sub-components of plasma, especially in regards to measuring insulin. After the 4 hours, it is known that “insulin” is no longer clearly defined in the plasma, therefore a “false negative” value shows. This happens too often and a clear IR diagnosis is “missed” because of the “artificially low” insulin value. Also, it is not necessary for your horse to fast from hay before the draw. Fasting from food only means that they should not be fed their “feed” 2 hours prior to the draw, otherwise, they may eat all the hay that they need.
Having blood work done may show you things about your horse that you didn’t realize were present. This has saved many horse’s lives. When For Love of the Horse gets blood work, we take it very seriously and work fast and hard to get the caretakers the answers they are looking for. The more you know about what tests are needed and how the blood needs to be handled, the more you will be able to help your horse. Knowledge is power all around. Your horse will benefit from your knowledge!