Page 510 - Problem-Based Feline Medicine

502 PART 7 SICK CAT WITH SPECIFIC SIGNS

here to include most cases of consumptive thrombocy- – In the author’s opinion, firm diagnostic criteria
topenia and microangiopathic disorders. should not be used. Rather, the probability of
DIC increases with the number of consistent lab-
Acute DIC is not as common in cats as in dogs. The
oratory abnormalities: e.g. it is possible that a cat
most common causes are panleukopenia virus infec-
with only thrombocytopenia has DIC, it is more
tion, other overwhelming infections (e.g. cytaux-
likely that a cat with thrombocytopenia and pro-
zoonosis), and neoplasia.
longed ACT has DIC, while it is highly probable
The most common causes of subacute to chronic that a cat with thrombocytopenia, prolonged PT
DIC are liver diseases, neoplasia and FIP (due to and aPTT, hypofibrinogenemia and increased
vasculitis). FDPs has DIC. Scoring systems based on this
approach have been used in humans.
Thrombocytopenia has also been noted with several
● Measuring antithrombin III, which tends to be
other diseases (see Miscellaneous diseases, page 505),
consumed in DIC, may add specificity but probably
where the thrombocytopenia is likely consumptive in
does not increase sensitivity to the diagnosis of
origin.
DIC.
● Measurements of D-Dimer are being used with
Clinical signs increasing frequency to support the diagnosis of
DIC in dogs. Little is currently known of the utility
Signs of the primary disease. of D-dimer assay in the diagnosis of DIC in cats.
Most DIC is subclinical. D-dimer is a more specific marker of thrombosis
than are FDPs, but D-dimer is not specific for DIC.
Superficial and deep spontaneous bleeding may occur, D-dimer levels will be increased in thromboem-
but it is uncommon. bolic disorders including arterial and pulmonary
Venepuncture and biopsy sites, suture lines, and inter- thromboembolism.
nal and external injuries may bleed excessively. ● There is poor correlation between degrees of coagu-
lation abnormalities, severity of underlying clinical
Signs due to anemia and local effects of hemorrhage disease and risk for hemorrhage.
vary with severity of blood loss.

Differential diagnosis
Diagnosis
Differential diagnoses for the various primary diseases
Identification of a primary disease. are discussed throughout this book. If a hemostatic
defect is identified in the work-up of the primary dis-
Diagnosis is controversial in all species and there is not
ease, the possibility of a defect unrelated to the primary
a single test or combination of tests that rules in or rules
disease should be considered, e.g. Hageman trait.
out DIC.
Differential diagnoses for abnormal hemostasis with
Laboratory abnormalities consistent with DIC
liver disease include vitamin K deficiency, synthesis
include:
failure and undetermined causes (which might be mild
● Low platelet count, prolonged ACT, prolonged
DIC).
aPTT, prolonged PT, prolonged TT, hypofibrino-
genemia, decreased antithrombin III concentration, In cats with neutropenia due to myelosuppression and
presence of FDPs, and red blood cell fragments. secondary sepsis, thrombocytopenia may be due to
● One approach uses presence of three of the above concurrent megakaryocytic hypoplasia rather than DIC.
abnormalities (counting prolonged PT and/or
aPTT as one abnormality) as criteria for diagnosing
Treatment
DIC.
– Another approach uses low platelet count, pro- Treat the primary disease.
longed PT, prolonged aPTT, and prolonged TT ● This is the most important treatment. If this is not
as diagnostic of DIC in liver disease. possible, other treatments will ultimately fail.