Page 1422 - Small Animal Internal Medicine, 6th Edition

1394 PART XIII Hematology

principles are discussed in the following paragraphs. In kg) of EACA, orally (PO) q8h for 5 days, successfully pre-
general, a patient with a spontaneous bleeding disorder vents or resolves spontaneous bleeding. We have also used
VetBooks.ir should be managed aggressively because these disorders this protocol successfully in thrombocytopenic dogs, dogs
with bleeding hemangiosarcomas, trauma patients, and
are potentially life-threatening; at the same time, iatrogenic
bleeding should be minimized. As a general rule, trauma
A recent study of tranexamic acid, used as a 10 mg/kg IV
should be minimized, and the patient must be kept quiet, those with hemophilia.
preferably confined to a cage and leash-walked, if necessary. injection followed by q3h infusion (10 mg/kg) did not result
Exercise should be avoided or markedly restricted. in toxicity or consistent changes in TEG results (Kelmer
Venipunctures should be done with the smallest gauge et al., 2015); rapid IV injection of tranexamic acid typically
needle possible, and pressure should be applied to the punc- induces vomiting.
ture site for a minimum of 5 minutes. A compressive bandage Recent studies evaluated the efficacy of both aminoca-
should also be applied to the area once pressure has been proic acid or Yunnan baiyao, a traditional Chinese herbal
released. If repeated samples for packed cell volumes (PCVs) drug, in both normal dogs and dogs with bleeding right
and plasma protein determinations are necessary, they atrial masses and pericardial effusion.
should be obtained from a peripheral vein with a 25-gauge One study found Yunnan baiyao to be safe but it did not
needle to fill one or two microhematocrit tubes by capillarity. induce changes in the TEG tracing or parameters in 10
A bandage should be applied after each venipuncture. normal Beagles (Frederick et al., 2017); however, Tansey
Invasive procedures should be minimized. For example, et al. (2018) reported that using it at a dosage of 1 capsule
urine samples should never be collected by cystocente- q12h in client-owned dogs of over 15 kg, this herb increases
sis because of the risk of intraabdominal, intravesical, or clot strength and is well tolerated. Reported dosages for this
intramural bladder bleeding. Certain invasive procedures, compound range from 1 capsule once a day to 3 capsules 3
however, can be performed safely. These include bone times a day.
marrow aspiration, fine-needle aspiration (FNA) of lymph In a retrospective case-controlled study of 67 dogs with
nodes or superficial masses, FNA of the spleen (the thick right atrial masses and pericardial effusion, both Yunnan
fibromuscular capsule of the carnivore spleen seals the baiao and aminocaproic acid, either singly or in combina-
needle hole as soon as the needle is removed), and intrave- tion, were found to be safe (Murphy et al., 2017) but they did
nous catheter placement, although seepage from the catheter not significantly affect outcome, when compared with control
is common in thrombocytopenic patients. dogs.
Certain types of surgeries can also be safely performed in
some cats and dogs with coagulopathies. For example,
pedicle surgery (e.g., splenectomy) can be performed with PRIMARY HEMOSTATIC DEFECTS
minimal bleeding (i.e., seepage from the abdominal wound)
in dogs with marked thrombocytopenia (i.e., <25,000 Primary hemostatic defects are characterized by the pres-
platelets/µL). ence of superficial and mucosal bleeding (e.g., petechiae,
A transfusion of blood or blood components is indicated ecchymoses, hematuria, epistaxis) and are usually associated
in some dogs and cats with spontaneous bleeding disorders. with thrombocytopenia. Platelet dysfunction is a rare cause
WFB or a combination of packed RBCs and fresh-frozen of spontaneous bleeding in dogs and cats. Primary hemo-
plasma (FFP) should be used if the animal is anemic and static defects caused by vascular problems are extremely rare
lacking one or more clotting factors; plasma transfusions are and thus are not discussed here. These defects are the most
of no benefit in thrombocytopenic animals. FFP can be used common cause of spontaneous bleeding in dogs seen at our
to replenish clotting factors in a cat or dog with a normal or hospital.
mildly decreased PCV (i.e., the animal is not symptomatic).
Although it was traditionally thought that stored blood and THROMBOCYTOPENIA
frozen plasma were deficient in factors V and VIII and were Thrombocytopenia represents the most common cause of
not hemostatically active, it was recently demonstrated that spontaneous bleeding in dogs seen at our clinic. Decreased
frozen, 5-year-old plasma is hemostatically active (Urban numbers of circulating platelets can be the result of one or
et al., 2013). In general, WFB, platelet-rich plasma, and more of the following abnormalities (Box 87.4):
platelet transfusions rarely provide sufficient platelets to halt
spontaneous bleeding in a cat or dog with thrombocytope- • Decreased platelet production
nia, particularly if the bleeding is the result of platelet con- • Increased platelet destruction
sumption. Some guidelines for transfusion therapy are • Increased platelet consumption
discussed in Chapter 82. • Increased platelet sequestration
Nonspecific procoagulants such as epsilon-aminocaproic
acid (EACA) or tranexamic acid have been used successfully Increased platelet destruction represents the most
to manage spontaneous bleeding in a variety of clinical situ- common cause of thrombocytopenia in dogs in our clinic
ations (Marin et al., 2012a and b). In Greyhounds with but is rare in cats. Usually, the peripheral destruction of
delayed postoperative bleeding, 500 to 1000 mg (≈15-50 mg/ platelets results from immune-mediated, drug-related, and