Page 495 - Problem-Based Feline Medicine

23 – THE BLEEDING CAT 487

within organs), dysuria due to a clot within the bladder, – Bleeding from mucosal surfaces – epistaxis,
and possibly vomiting due to a clot within the stomach. melena and hematuria.
– Intraocular hemorrhage.
– Risk of spontaneous bleeding is related to the
WHERE? platelet count, but quantification of the risk is
imprecise, in part because of imprecision in
Bleeding may be the result of a local lesion or a distur-
platelet counting, especially in cats (see discus-
bance in primary or secondary hemostasis.
sion below). The following values are derived
Bleeding from a local lesion may occur into or from from humans and dogs; cats are at less risk of
any tissue and is appropriate for the severity of the bleeding for a given platelet count. Indeed, signs
lesion. of clinical bleeding in cats are usually absent or
● Bleeding varies with the severity, type and location mild until almost no platelets are evident on a
of lesion. Hemostasis may be insufficient to stop blood smear. Bleeding is worse at a given platelet
bleeding, and manipulation of the lesion may reac- count if there is concurrent vasculopathy, platelet
tivate bleeding. function defect, coagulopathy, fever, or, possibly,
● Presence of blood clots in shed blood rules out a anemia.
9
typical coagulopathy, but not a platelet disorder, as – Platelets < 80 × 10 /L (< 80 000/μl) – increased
the cause of bleeding. bleeding at surgery.
9
– Platelets < 50 × 10 /L (< 50 000/μl) – micro-
Absence of blood clots in shed blood does not rule in a
scopic spontaneous bleeding.
coagulopathy.
9
– Platelets < 20 × 10 /L (< 20 000/μl) – mild risk of
● Initial bloodshed may be too rapid to immediately
spontaneous clinical bleeding.
activate coagulation (e.g. laceration of a large vessel).
9
– Platelets < 10 × 10 /L (< 10 000/μl) –moderate
● Clots may have been removed (e.g. swallowed) and
risk of spontaneous clinical bleeding.
only red blood cells not incorporated into the clot
9
– Platelets < 5 × 10 /L (< 5 000/μl) – severe risk of
remain.
spontaneous clinical bleeding.
● Clot lysis may have occurred.
● Excessive bleeding may be characterized by:
● Blood in body cavities and the intestinal tract may
– Occurrence immediately following injury,
not clot because of defibrination on epithelial sur-
because the initial platelet plug does not form.
faces and clots may be digested.
– Increased rate of bleeding.
Vascular disorders may result in either spontaneous or – Prolonged bleeding.
excessive bleeding at the site of the disorder. – Prolonged bleeding after venepuncture is
● Vascular disease secondary to systemic hyperten- one of the most common initial signs of
sion commonly causes retinal hemorrhages and less thrombocytopenia. It should not be dismissed
commonly epistaxis. and attributed to the venepuncture technique in
● Other vascular disorders are not common causes of a cat at risk for a bleeding disorder.
bleeding in cats.
Coagulopathies may result in either spontaneous or
Platelet disorders may result in either spontaneous or excessive bleeding.
excessive bleeding. ● Spontaneous bleeding occurs because vasocon-
● Spontaneous bleeding occurs because blood ves- striction and platelet plugs are insufficient to stop
sel walls are continuously sustaining minute bleeding from larger vessels. Coagulation is neces-
injuries and being plugged by platelets. A platelet sary, and a coagulopathy permits bleeding from
disorder permits bleeding at sites of minute injury larger vessels into tissues and body cavities result-
in small vessels resulting in the following signs: ing in the following signs:
– Bleeding at multiple sites. – More localized bleeding (although widespread
– Petechiation and ecchymoses, especially in hemorrhage may occur).
dependent areas and areas subject to normally – Subcutaneous hematomas and intramuscular
high wear and tear (e.g. gums). hemorrhages.