Page 198 - Basic Monitoring in Canine and Feline Emergency Patients

The other common thrombocytopathies encoun- present with signs of hypovolemia including poor
tered are drug induced, occurring after receiving pulses, tachycardia, pale mucous membranes, and
VetBooks.ir non-steroidal anti-inflammatory drugs (NSAIDS) obtundation.
or anti-platelet medications such as clopidogrel. In
the case of these drugs, platelet activation is
blocked either by inhibiting endogenous platelet 9.4 Interpretation of the Findings
activator production such as thromboxane A Primary hemostasis
2
(NSAIDS) or blocking receptors that lead to plate-
let activation (ADP receptors; clopidogrel). There is With primary hemostatic disorders, treatment
some research in human medicine indicating that options are limited and highly dependent upon the
colloid administration can also affect platelet func- animal’s clinical condition as well as the underlying
tion through a variety of mechanisms although this cause of the platelet-related disorder. The approach
has not been definitively proven in animals. Please to these cases can be divided into the emergent,
see Further Reading section for a more comprehen- urgent, and stable categories. See Fig. 9.12 for an
sive listing of thrombocytopathies. overview of the approach to these cases.

Secondary hemostatic disorders Emergent primary hemostatic disorders
Secondary hemostatic disorders affect the clotting Emergent cases typically are those animals that
factors and range from inherited deficiencies of are either unstable due to anemia from blood loss
specific factors (e.g. hemophilia A with a lack of and/or actively hemorrhaging with documented develop-
factor VIII) to widespread deficiencies of multiple ment of anemia over time. In cases of thrombocy-
clotting factors. The most common example of the topenia, these are classically patients with platelet
latter is a lack of functional vitamin K-dependent counts less than 10,000 cells/hpf. A good example
clotting factors (i.e. factors II, VII, IX, and X) due is an animal with persistent epistaxis resulting in
to anticoagulant rodenticide intoxication or liver anemia or persistent GI hemorrhage that leads to
disease. However, diseases such as disseminated anemia over the course of several days. In these
intravascular coagulation will also affect multiple situations, it is important to stop the bleeding so
coagulation factors simultaneously. See Further that red blood cells can either be transfused to
Reading section for a more comprehensive listing improve the anemia or the patient is able to replace
of the various secondary hemostatic disorders red blood cells on its own.
found in dogs and cats. The only option available to emergently stop
Clinical signs associated with secondary hemo- hemorrhage due to platelet-related bleeding is to
static disorders are generally associated with bleed- transfuse platelets to the patient. There are several
ing into larger cavities. This is attributed to the fact options that can provide platelets: fresh whole
that although the platelets are present, there is an blood or platelet-rich plasma. Other products
inability to form fibrin crosslinking of the platelets, touted to provide platelets such as frozen platelet
resulting in a lack of a ‘hard clot.’ Larger quantities concentrates or lyophilized platelet products are
of bleeding than are typically seen with platelet dis- controversial as to the efficacy of the platelets avail-
orders ensue. Common locations for bleeding from able in the product and the authors suggest doing
secondary hemostatic disorders include pleural research into their efficacy prior to using them.
effusion, abdominal effusion, joint effusion, or
bleeding into the lung parenchyma itself, although
bleeding can theoretically occur anywhere. The Urgent primary hemostatic disorders
clinical signs noted in a patient are consistent with Urgent cases are those cases with known thrombo-
where the blood accumulates. For example, respira- cytopenia or thrombocytopathia which are not
tory distress occurs with pleural effusion or bleed- currently bleeding but which require a procedure
ing into the pulmonary parenchyma. Hemoptysis is known to induce bleeding. In thrombocytopenic
also common with intrapulmonary hemorrhage. patients, these animals typically have platelet
Lameness may be present with hemorrhage into counts of 10,000–50,000 platelets/hpf. An example
joints. No matter the location of the bleeding, if the of such a procedure would be surgery to obtain diag-
animal loses a large enough blood volume, it can nostic biopsy samples or a bone marrow aspirate to

190 E.J. Thomovsky and A.C. Brooks