Page 87 - Speedhorse, December 2018

not only to diagnose an infection, but also as a relatively inexpensive tool to gauge the horse’s response to treatment,” she says.
Another protein that is useful in this capacity is Serum Amyloid A. “New advances in running this test have made it more readily available to practitioners and it is an extremely sensitive marker of inflam- mation and infection.”
These various tests can give clues regarding the health of the horse. Routine bloodwork drawn annually can be a very good indicator of how the horse is doing, systemically. “For instance, certain organ values that are creeping up in older horses can be a harbinger of problems,” according to Arbittier.
“We run these screening tests for any number of reasons. For instance, we might run tests on a horse with a fever of known
or unknown origin, a horse with an obvious disease process such as nasal discharge/ cough, a horse who is lethargic or has lost weight, for a pre-purchase exam, or as part of routine annual exam on geriatric horses. Once we have baseline values in a sick horse, we can use some of them to help monitor how a certain treatment is working. It’s good to have baseline values that are taken when your horse is normal because then you can compare them to test results later on
in the horse’s life and see how things have changed,” she says.
SERUM BIOCHEMISTRY PROFILE
If a horse seems to be ill and the veterinar- ian is unsure about what might be going on, blood might be drawn
for a serum biochemistry
profile, which refers to the
chemical analysis of blood
serum, says Dr. Katherine
Wilson, Clinical Assistant
Professor, Large Animal
Medicine, Virginia-
Maryland Regional College
of Veterinary Medicine,
Blacksburg, Virginia.
A complete blood count examines the horse’s red and white blood cell counts.
“This panel has
values on it associated
with kidney function and
liver damage, along with
most of the electrolytes,
such as sodium, potas-
sium, chloride, and so
on,” says Wilson. “Electrolytes in the blood can change quickly, due to dehydration or loss through diarrhea, or via urine, if the kidneys are not functioning normally. Thus, the chemistry profile gives us quite a bit
of information if there are things that are abnormal.”
The serum chemistry test helps the veterinarian get an idea about the function of internal organs. It helps the veterinarian evaluate systems such as the liver, kidneys, or muscles. Results of the serum chemistry can also give information about the various electrolytes. It helps determine if the
horse is in good health or if there is some- thing abnormal going on that will need further exploration.
A lot of the values being checked are enzyme levels. Various enzymes are found inside the cells, and when the cell is sick
or damaged, these enzymes leak into the bloodstream. If certain enzyme levels in the blood are increased, this could indicate cell
damage. However, a lot of these enzymes are not found in just one place in the body, so the veterinar- ian has to look at the whole picture to figure out what’s happening. The veterinarian must be a detective to find and understand the clues.
Wilson says the exact tests included in a serum chemistry panel will vary from lab to lab. Some of the values
are the same ones looked at in dogs,
cats or humans, and some will be different. Not every species’ physiol- ogy is the same, so there will be some variation when checking horses.
When doing basic bloodwork, the veterinarian would look at things that indicate kidney values,
such as creatinine, which promotes muscle and brain energy. The blood chemistry provides a broad look at possible problems with the liver or kidneys, if certain enzymes in the blood are elevated. These would give clues regarding liver or kidney function, to help determine whether it is normal or not.
“The liver values on this panel are mostly enzymes that are produced by cells in the liver,” explains Wilson. “If these values are elevated, this usually just means there has been some damage to the liver. Those cells essentially rupture, and those enzymes are floating around in the bloodstream at higher concentration,” she says.
“One thing we emphasize is that just the fact those enzymes are elevated or there is evidence of liver damage doesn’t necessarily mean the liver isn’t functioning normally. It may still be able to do all the things it needs to do in spite of the damage, and it can sometimes heal from that damage. It might be temporary,” she says. The same thing is true for the kidneys. They can take quite a bit of damage and still function normally.
“Another thing that is commonly found to be high in bloodwork on horses is one
of the liver values called bilirubin, which
is formed in the liver by the breakdown of hemoglobin. This can increase fairly rapidly when horses go off feed, and this is some- thing unique to the horse. Often, we get phone calls from vets who don’t work on horses much, or owners who see the blood- work and note that the bilirubin is above normal range and are concerned about liver disease. If the horse is off feed for 24 to 48 hours, that value will rise, but this is just temporary elevation,” explains Wilson.
TESTS FOR SPECIAL DISEASES
Tests for specific diseases may be run if
a veterinarian suspects that the horse may have a particular disease or as rule-outs when a horse is showing vague signs that are not very specific. “Sometimes, the specific disease tests are run in a screening capac- ity to have a baseline for future use. Lyme
Dr. Katherine Wilson, Clinical Assistant Professor of Large Animal Medicine at Virginia- Maryland Regional College of Veterinary Medicine.
SPEEDHORSE, December 2018 85
EQUINE HEALTH