There are three main ways to measure fibrinogen concentration: 1) heat precipitation of EDTA samples to measure elevated levels in inflammation/renal disease, 2) thrombin clot time to measure functional fibrinogen levels and detect deficiencies, 3) clottable fibrinogen concentration determined using thrombin clot time and compared to a standard curve. Normal fibrinogen levels vary between species but are generally 100-500 mg/dl in horses, sheep, and dogs and 300-700 mg/dl in cows. Elevated levels indicate inflammation.

1. Tests for fibrinogen
Fibrinogen concentration can be
measured in 3 ways. Fibrinogen
concentration is usually reported in
milligrams per deciliter (mg/dl).
1. Heat precipitation: This test is
performed on EDTA samples only and
is used for determination of fibrinogen
concentration as an indicator of
inflammation in large animals.
Fibrinogen is an acute phase reactant
protein and elevated values are seen in
inflammation and renal disease (for the
latter, in the cat and cow especially).
This method of fibrinogen
determination is not sensitive enough
to detect decreased fibrinogen
concentration in coagulation
abnormalities. The method is as
follows:
Two microhematocrit tubes are filled

2. with EDTA-anticoagulated blood. One
is centrifuged and the total protein in
the plasma is measured by
refractometer. The second tube is
heated at 56 C for 3 minutes, which
precipitates the fibrinogen. The second
tube is then centrifuged and the protein
result read similarly. The protein result
in the heated tube is subtracted from
the result in the unheated tube; the
difference is equivalent to the
fibrinogen that was removed from the
plasma in the second tube by heating
and centrifuging.
2. Clotting method - thrombin clot
time: The clotting method is a direct
measurement of functional fibrinogen.
This method involves the thrombin
clot time (TCT), which is the time
taken for a standardized thrombin
solution to convert fibrinogen to fibrin
to form a clot. Clot formation is

3. decreased (which will prolong the
TCT) if there is a deficiency of
(hypofibrinogenemia) or abnormal
(dysfibrinogenemia) fibrinogen. This is
the technique used by the Comparative
Coagulation Laboratory at Cornell
University for measurement of
fibrinogen in citrated plasma samples
(and is usually a part of the coagulation
panel). Therefore, the TCT will be
prolonged with:
1.
Inherited and acquired
hypofibrinogenemia or
dysfibrinogenemia;
DIC consumption of fibrinogen);
2. H
Heparin therapy (for preventing
thrombosis)
3. S
ynthetic liver failure (resulting in

4. decreased fibrinogen production).
3.Clotting method - fibrinogen
concentration (clottable fibrinogen):
Fibrinogen concentration is determined
using the TCT, where the time taken
for the patient's sample to clot is
compared to a standard curve prepared
from (preferably) species-specific
fibrinogen. The TCT is inversely
proportional to the fibrinogen
concentration, therefore a long TCT
indicates a hypofibrinogenemia and
vice versa.
NORMAL VALUS :
Horse , sheep and dog 100 – 500
mg/dl
Cow 300 - 700
mg/dl
Plasma protein : Fibrinogen ratio
Normal 15:1 , abnormal 10:1except in
sever hypoproteinemia .
Interpretation : Estimation of plasma

5. fibrinogen have been compaired to
TLC and Neutrophil counts in dog . It
was concluded that fibrinogen
increases indicated the presence of the
inflammation
 Immunologic assays: Fibrinogen
antigen can be measured in
immunologic assays in which the
immunoprecipitate formed after
reaction with specific antifibrinogen
antisera is quantitated.