Page 86 - Speedhorse, December 2018

Blood Tests For Disease Diagnosis
“It’s good to have baseline values that are taken when your horse is normal because you can compare them to test results later to see how things have changed.”
by Heather Smith Thomas
There are times your veterinarian might use a blood test or combination of blood tests to try to determine what is going on with
a horse to help diagnose and pinpoint the cause of disease. Bloodwork, used in conjunction with clin- ical signs, a thorough examination of the horse, and a complete his-
tory of the horse, can give clues that might lead to proper diagno- sis and a good plan for treatment. Blood tests are often used in evaluating wellness or for a diagnosis when a horse is sick.
Liz Arbittier,
VMD, CVA, Staff
Veterinarian, Field
åService, New
Bolton Center,
University of
Pennsylvania, says
the most common
tests an equine veterinarian might run are the complete blood count (CBC), chemistry screen, and fibrinogen assay.
“These are general screening tests that can rule in or, equally as important but more frustrating, help rule out a disease process,” Arbittier says. A CBC examines the horse’s red and white blood cell counts.
“These include values such as packed cell vol- ume (PCV), which tells you the concentration of the red blood cells. A horse with a low value may be termed anemic, while a horse with a high value would be looked at first for dehydration and then for more serious disease,” she explains.
The red blood cell information can sometimes help the veterinarian focus on specific diseases, but is not very definitive. It could give a clue, but the veterinarian always has to look further to make a diagnosis. Horses usually don’t have big changes in red blood cell numbers, but it is not uncom- mon for horses to have red blood cell count a little lower than normal range. A lot of diseases or a chronic long-term disease can cause mild anemia.
“The CBC also tells you how many white blood cells (WBC) are in the sample as well as the
breakdown of the different categories of cells,” Arbittier says. This can help the veterinarian diagnose bacterial infection (high WBC) or a virus (low WBC) or even possible pending diarrhea or colitis (low WBC).
“The percentage breakdowns of different WBC’s can also help diagnose an allergic or parasitic process if one particular white cell, the eosinophil, is high. The appearance of the cells is also important in this evaluation, and sometimes blood-borne pathogens, such as the bacteria Anaplasma, can be visualized in the sample,” she says.
Chemistry screens may vary somewhat between laboratories, but they all provide information on liver, kidney, and muscle function, electrolyte levels, and protein levels. “This is a broad screen- ing test that gives you a lot of bang for your buck,” says Arbittier.
Checking for fibrinogen levels in the blood can also be useful. “Fibrinogen is an acute-phase protein generated by the equine liver that can indicate an inflammatory process if it is moder- ately elevated, and an infectious process if it is significantly elevated. This value can be utilized
The most common tests an equine veterinarian might run are the complete blood count (CBC), chemistry screen, and fibrinogen assay.
Liz Arbittier, VMD, CVA, Staff Veterinarian of the New Bolton Center at the University of Pennsylvania.
Heather Smith Thomas
84 SPEEDHORSE, December 2018
EQUINE HEALTH