In equine medicine, rarely do we recommend annual bloodwork be performed - which is somewhat expected to hear from your companion animal's veterinarian. Horses live longer, and fortunately are way less common to have auto-immune diseases, cancer (neoplasia), and organ dysfunction. That being said- there are still reasons to perform bloodwork on your horse(s) periodically, even when they're acting normal!
Let's break down what "routine" bloodwork typically entails. First, a CBC or complete blood count is standard. This shows the numbers and percentages of white and red blood cells, as well as relative volume of red blood cells and numbers of platelets. This can be extremely important in early infections, as the white blood cell fractions will change quickly- sometimes even before any signs of issues appear. Red blood cells' function is to oxygenate tissues- when they are in low numbers, horses can appear lethargic. The term for this condition is anemia. Anemia itself can have many causes; knowing that it's occurring in your horse is important! Also, some horses "normal" hematocrit is 28, whereas others live around 34 or 35. Knowing your horse's baseline values will help when bloodwork is drawn because of a malady.
Next, the blood chemistry is an important part of the picture. This panel of tests can include electrolytes (calcium, sodium, potassium, chloride), proteins (albulmin, globulin, and total protein), muscle enzymes (CK, AST, LDH), renal/kidney enzymes (Creatinine, BUN), and liver enzymes (Alk Phos, GGT, SDH). There are a lot of important numbers in a chemistry panel! Most notably, we get another baseline of your horse's values. Some horses are found to have high GGT values and can be completely asymptomatic. This could be confusing if your horse is hospitalized for colic and is dehydrated and has high bilirubin levels- it could appear to be a liver dysfunction/insult when in reality it's all related to the colic episode. Alternatively, we have found mild renal enzyme elevations on routine bloodwork- which makes us much more cautious when using NSAIDs or renal-impairing medications.
Lastly, a typical bloodwork panel for horses will include fibrinogen- an acute phase protein associated with inflammation. This can be very important in diagnosing bacterial infections, internal abscesses, and infections after surgical interventions. High values for fibrinogen (normal 200-500 with most labs) has been shown to correlate with poor prognosis versus mild elevations. At Heritage Equine Clinic we also use Serum Amyloid A (SAA), another acute phase protein to help us in cases with possible infections. SAA as a protein changes more rapidly than fibrinogen, so we can get up to date results within 10 minutes of our blood draw using a portable reader at the barn.
This post is not meant to scare you as a horse owner into checking your horse's blood frequently, but wellness bloodwork panels every year or two would be a good investment into your horse's future health! As always, feel free to call us at the clinic at 303-578-5898 with any questions!