|
If your horse requires blood tests to
help diagnose his/her condition, here are some of the most common counters
noted on test result reports. Blood tests are highly useful for
checking on the true health of your horse.
You can request a blood test from your
vet at any time to check his\her biochemistry. Doing this on a
regular basis, perhaps once a year with vaccinations or other scheduled
visits, is an excellent way to keep a check that you aren't under or over
supplementing before it becomes a severe problem.
Your vet may supply you with the
printout of your horse's results as well as telling you what they mean,
the following are usually on the printout:
PCV
Packed Cell Volume:
-
This is mostly the
percentage of cells within the blood. The red cells have the
larger percentage as there are usually 6-8 million/ml as against
white cells of 6-8 thousand/ml.
-
PCV is used to
assess dehydration and anaemia.
-
Optimum levels are
close to 40% with levels below 35% and above 45% likely to
indicate problems.
-
This reading is
also affected by excitement at collection.
-
PCV also rises as
fitness increases, often though, it keeps rising when problems
occur because dehydration is a common sequel of work-related
problems.
-
Generally a horse
is considered anaemic if the packed cell volume (PCV) is less
than 35% or less than 2 standard deviation units below that
horse's average count.
-
If you are
concerned your horse is anaemic then you are best to collect
blood within a few minutes of completing 800-1000 metres of
three-quarter pace work.
Mean
Corpuscular Volume: MCV
is the size of the red blood
cell and is important in two fields. One relates to anaemia cause
diagnosis.
-
If the figure is
high the horse has anaemia, the cause is usually blood loss
(ulcers, bleeder), Vitamin B6, B12, Folic Acid or niacin
deficiencies or gut upsets causing reduced production of these
vitamins.
-
If the figure is
low with anaemia, this usually indicates iron deficiency but
also copper or pyridoxine.
Mean
Corpuscular Haemoglobin Concentration: MCHC
is a measure of the amount of
haemoglobin in each red blood cell.
-
Usually this is in
a tight range of 35- 39%.
-
It cannot be above
40% so any reading with a figure greater than 40% is wrong.
-
Variations in MCHC
usually reflect problems in the other readings as most labs
calculate MCHC by dividing the haemoglobin by PCV and
multiplying by 100.
WBC
White Blood Cells, a high WBC means that an infection has been detected
and white blood cells are being created to fight the infection.
Proteins
6 proteins are usually listed, raised globulin and fibrinogen levels are
signs of
infection.
Biochemistry
will show up mineral deficiencies and shows enzyme levels. High
levels of enzymes can indicate cell damage (which causes enzymes to leak
into the blood stream).
The biochemistry
section reveals much about the nutrition of your horse - no matter how
much you feed your horse, if it is deficient or overdosed in one or two
key vitamins or minerals it cannot make good use of the nutrition you
provide.
It is important to recognise that because
the bulk of your horse's nutrition comes from forage (whether pasture or
hay) you are then reliant on the soil that this is grown on for the
minerals it contains. New Zealand (and many parts of North America)
soils are frequently deficient in Selenium, other parts of the world have
their own mineral characteristics and these are reflected in the forage
they produce. The only way to gauge what and how much to supplement
is either to have a complete analysis of all feeds (incuding each batch of
forage) or to have your horse blood tested. This is particularly
important with may minerals as they often have a very narrow threshold of
tolerance, over supplementing is just as dangerous as under supply.
- "Gram's
Stains"
are simply an analysis of the types and
quantities of organisms e.g. bacteria that are present in a sample of
blood or fluid. The sample is sent off to a laboratory for
analysis and are cultured to identify the organisms present.
Effective treatment by antibiotics or other drugs can only be achieved
if the drug is correct for the type of organism.
- Gram Negative
Bacilli - This describes
several groups of organisms rather than a lack of bacteria which the
name seems to imply.
- Leucocytes
(leukocytes) Test results may
refer to the presence of or provide a count of leucocytes and/or other
cells of the lymphoid system. These cells which originate in the
bone marrow or liver have various roles in fighting infection.
There are four major cell types'; erythrocytes,platelets (promote blood
clotting and inflammation), granulocytes and monocytes/macrophages and
lymphocytes and natural killers.
|
|
First Aid |
When reading your horse's blood test results you (and your vet) should
also consider the following factors.
- The only thing that causes haemoglobin to
rise is work. All that additives do is provide the raw materials to make
haemoglobin, no work means no rise in haemoglobin. Horses in the paddock do
perfectly well on 10.5 - 12.5 and when they return to the stables, these are
normal readings. The aim of training is to stress the system so the
bone marrow makes more haemoglobin for the workload, thus, a gradual
increasing workload is best.
- Young horses will usually achieve adult
iron levels by the time they are yearlings and the PCV of two year olds in
training will usually increase by about 4% per month for the first 5 months,
after which it will generally remain stable.
- Measuring the red blood cell count is
generally considered to be paramount. However, a horse at rest will have 50%
of his red blood cells lying in wait within his spleen. These red cells are
then released under the effect of adrenalin when excited or exercising. So,
while measuring red cell counts at rest is useful it doesn't tell you the
total number of red cells available during exercise.
- There can be up to 20% variation in a
horse's red cell count over a single week.
- Post exercise bloods may be more reliable
and some studies have shown a relationship between higher haemoglobin levels
and performance. Ideally a fit healthy horse should have a PCV of 60-65% and
Hb 200-230 of gm/L after exercise.
- Once collected blood should be analysed
within 6 hours to prevent abnormal results. Storing blood for greater than
12 hours will result in lower red cell counts, lower glucose levels and
abnormal levels of muscle enzymes (AST) and electrolytes.
|
