Page 513 - Problem-Based Feline Medicine

23 – THE BLEEDING CAT 505

Concurrent thrombocytopenia or thrombocytopathia Vitamin K antagonist poisoning – PT is prolonged as
was believed to have triggered bleeding in a cat follow- well as aPTT.
ing modified-live virus vaccination. This would appear
DIC – thrombocytopenia is often present, in addition to
to be an uncommon event, and is not reported in
signs of a primary disease.
humans with Hageman trait.
Acquired factor XII deficiency has been reported in
Humans with Hageman deficiency are at increased risk
humans but not in cats.
for thromboembolic events as a result of a deficient fib-
rinolytic system. It is not known if cats with Hageman
trait and cardiomyopathy are at increased risk of arte- Treatment
rial thromboembolism.
None required.
It is not known if cats with Hageman trait have blunted
inflammatory responses.
Prognosis
Diagnosis Normal life expectancy.
No signs of abnormal bleeding unless another disease
process affecting hemostasis is present. Transmission
Hageman trait is the most common inherited coagu- Factor XII deficiency is a heritable single-gene defect
lation factor deficiency in cats, but prevalence is not that is autosomal recessive.
known. Although stated to be common, recent large retro-
spective reviews of hemostatic disorders in sick cats
Prevention
have not identified any cases.
Probably none is required.
Hemostatic testing reveals normal platelet count and
BMBT, normal PT, and markedly prolonged ACT and
aPTT (e.g. aPTT > 50 s, often > 100 s, where the upper
MISCELLANEOUS DISEASES*
limit of normal range is 25 s).
Definitive diagnosis is based on quantification of fac- Classical signs
tor XII activity (FXII:C), similar to the diagnosis of
● Signs of the primary disease.
hemophilia A, and ruling-out acquired factor XII defi-
ciency (see Circulating anti-coagulant, below).
Clinical signs
Differential diagnosis Thrombocytopenia, increased ACT/aPTT/PIVKA
time, or decreased antithrombin III levels have been
Hemophilia A, B (and C) are the main differential
noted in various diseases not typically associated with
diagnoses for markedly prolonged ACT and aPTT as
bleeding tendencies. Diseases include hypertrophic car-
solitary abnormalities.
diomyopathy, congenital cardiac disorders, pleural
If a cat is presented with bleeding and a prolonged ACT effusions not due to feline infectious peritonitis, dia-
and aPTT are found, a judgment must be made as to betes mellitus, hyperthyroidism, hypertension, chronic
whether the bleeding is appropriate for the injury. For renal failure, urinary tract infection, urethral obstruction,
example, a cat with hemothorax and prolonged ACT rhinitis, Mycoplasma haemofelis infection (haemo-
and aPTT could have hemophilia A or chest trauma and bartonellosis), primary neurologic diseases, and non-
Hageman trait, but in the former case there would be no anti-coagulant toxicoses.
evidence of injury.
DIC may be the mechanism for at least some of these
Hemophilia B and Hageman trait have occurred con- abnormalities. The close interaction between the
currently. intrinsic system and inflammation via factor XII