Page 1419 - Small Animal Internal Medicine, 6th Edition

CHAPTER 87 Disorders of Hemostasis 1391

instrument performs determinations of the aPTT or OSPT thrombosis or TE. The FDP test is also positive in more than
with only a small volume of blood for each test; nonanticoag- half of dogs with bleeding caused by rodenticide poisoning,
VetBooks.ir ulated or citrated samples can be used. The reference ranges likely because vitamin K antagonists are believed to release
fibrinolysis by inhibiting the production of PAI-1.
for the aPTT with this instrument are different from those
A fourth point-of-care test that can be performed primar-
for the aPTT determined in referral diagnostic laboratories.
The third real-time test that can be easily performed in ily in dogs is the BMBT (Box 87.2), in which a template
practice is determination of the FDP or D-dimer concentra- (SimPlate, various manufacturers) is used to make an inci-
tion with the commercially available latex agglutination tests; sion in the buccal mucosa and the time until bleeding com-
circulating FDPs or D-dimers are generated during the cleav- pletely ceases is determined. The BMBT is abnormal in cats
age of fibrin and fibrinogen (i.e., fibrinolysis) before or after and dogs with thrombocytopenia or with platelet dysfunc-
binding to factor XIII, respectively. This test is commonly tion. In an animal with clinical signs of a primary bleeding
positive in dogs, some cats with DIC, and some patients with disorder (e.g., petechiae, ecchymoses, mucosal bleeding) and
a normal platelet count, a prolonged bleeding time indicates
an underlying platelet dysfunction (e.g., resulting from
NSAID therapy or vWD) or, less likely, a vasculopathy.
Intrinsic system Extrinsic system
PK Tissue
HMWK Factor
XII
XI VII BOX 87.2
IX
VIII Procedure for Determining Buccal Mucosa Bleeding
Time in Dogs
Common pathway
1. Position the animal in lateral recumbency with manual
X
V restraint.
II 2. Place a 5-cm wide strip of gauze around the maxilla
aPTT I OSPT
ACT to fold up the upper lip, causing moderate
XIII
engorgement of the mucosal surface.
3. Position the SimPlate against the upper lip mucosa
Fibrin and push the trigger.
4. Start a stopwatch when the incisions are made.
FIG 87.2 5. Blot the blood with a gauze or blotting paper placed
Traditional intrinsic, extrinsic, and common coagulation 1 to 3 mm ventral to the incision without dislodging
pathways. ACT, Activated coagulation time; aPTT, activated the clot.
partial thromboplastin time; HMWK, high-molecular-weight 6. Stop the stopwatch when the incision ceases to bleed.
kininogen; OSPT, one-stage prothrombin time; PK, 7. Normal times are 2 to 3 minutes.
prekallikrein.

A B

FIG 87.3
Illustrative depiction of primary (A) and secondary (B) hemostatic bleeding. A,
Development of petechiae and ecchymoses. B, Formation of a hematoma or blood in a
body cavity. For a detailed description, see text. (Artwork by Tim Vojt. Reproduced with
the permission of The Ohio State University.)