Page 545 - Problem-Based Feline Medicine

24 – THE ANEMIC CAT 537

Most bleeding disorders will have evidence of
PLATELET ABNORMALITIES (PRIMARY
HEMOSTATIC DEFECTS)** hemorrhage in more than one site. The fundus of
the eye, mucous membranes of the mouth, vulva,
and penis, and the skin especially ear and ventral
Classical signs
abdomen are good places to evaluate for evidence of
● Anemia. hemorrhage.
● Petechiae and ecchymoses at more than
one site.
● Hemorrhage involving fundus of the eye, Diagnosis
mucous membranes of the mouth, vulva,
and penis, and skin including ears. Platelet count should be made; spontaneous hemor-
rhage generally occurs with platelet counts of
< 50 000 platelets/μl.
Pathogenesis
Platelet estimates can be made; under oil immersion
Platelet diseases can be divided into those inducing
(1000×), every one platelet per field equates to
thrombocytopenia and those inducing platelet dys-
approximately 20 000 platelets/μl.
function.
When thrombocytopenia is suspected, scan the blood
The differential categories for thrombocytopenia
smear evaluating for clumps which may falsely lower
include consumption, destruction, decreased produc-
the count.
tion and sequestration.
If giant platelets are present, decreased production of
The most common causes of platelet consumption are
platelets is unlikely.
disseminated intravascular coagulation and con-
sumption at sites of inflammation. If persistent thrombocytopenia is present, a bone mar-
row examination is indicated to evaluate for myeloph-
The most common cause of platelet destruction is
thitic disease and latent feline leukemia virus
immune-mediated which can be either primary or sec-
infection (IFA or PCR; see FeLV section).
ondary to drugs and vaccines.
Platelet function deficits in cats are rare, however von
Platelets are produced by the bone marrow and so any
Willebrand’s disease does occur.
bone marrow disease can potentially result in thrombo-
cytopenia. Neoplasia and feline leukemia virus are Bleeding time assesses platelet function and should be
common examples. less than 5 minutes.
Sequestration of platelets usually occurs in the spleen Bleeding time should only be performed in cats with
or liver but is not a primary disease. normal platelet counts and factor tests (ACT, etc.).

Platelet function abnormalities can be iatrogenic
(aspirin), congential (rare in cats), or acquired
(hyperglobulinemia). Treatment
Treatment varies with the primary disease (see
appropriate section) but frequently includes administra-
Clinical signs
tion of fresh whole blood transfusion if life-threaten-
Diseases of platelets usually result in petechiae and ing hemorrhage is occurring.
ecchymoses.
Fresh plasma can be used if red blood cells are not
Ingestion of aspirin may be known. needed.
Clinical signs are usually consistent with where the pri- For suspected secondary immune-mediated thrombo-
mary bleeding is occurring and the primary disease cytopenia, remove the potential source if possible
resulting in hemorrhage. (antibiotic or vaccine).