Page 1050 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

H aemolymphatic system 1025

VetBooks.ir 9.27 DISSEMINATED INTRAVASCULAR
COAGULOPATHY

Definition/overview
DIC is a potential complication of many serious
illnesses, particularly intestinal accident, meta-
static neoplasia and gram-negative sepsis. With
an appropriate inciting stimulus, simultaneous
widespread activation of the clotting process and
consumption of clotting factors may lead to con-
current formation of thrombi and a tendency to
bleed, respectively.
Fig. 9.27 Blood smear from a horse recovering from
thrombocytopenia. Note the large platelet in the Aetiology/pathophysiology
centre of the field with a normal-sized platelet above DIC may accompany many serious diseases
(Wright’s stain). including GI accidents, endotoxaemia, neopla-
sia, severe burns, liver disease, IMHA and snake
envenomation. Widespread or localised endothe-
hyperplastic. Tests documenting the presence of anti- lial injury (e.g. vasculitis) results in the initiation
body on platelets and megakaryocytes exist but are of both platelet plug formation and thrombin gen-
not widely available. eration. Platelets are consumed in the formation
of numerous platelet plugs. Widespread throm-
Management bin generation ensues, with deposition of fibrin
If an underlying cause is found and is treatable, strands in vascular spaces. Pro- and anticoagulant
this is the primary mode of therapy. Any ongo- factors rapidly become limited and fibrinolysis can
ing drug therapy should be stopped, if possible. If predominate.
ongoing treatment is required, then drug classes
(i.e. antimicrobial classes) should ideally be switched. Clinical presentation
Immunosuppressive drugs to reduce antigen– Horses exhibit clinical signs of the primary underly-
antibody complexes are usually required, often for ing disease process and multiple-site haemorrhage.
a minimum of 3 weeks. The most common ini- Bleeding from the nose and other mucosal surfaces
tial treatment is administration of dexamethasone is possible, and petechial and ecchymotic haemor-
(0.05–0.2 mg/kg i/v or i/m q12–24 h, tapered gradu- rhages may be observed (Fig. 9.28). If thrombi
ally based on response to treatment). Azathioprine develop, clinical signs related to dysfunction of the
(3 mg/kg p/o q24 h) has been used in refractory cases affected organ will occur (e.g. dyspnoea with pulmo-
or where complications of dexamethasone therapy nary thrombi).
(e.g. laminitis) have developed. Recurrent bouts of
thrombocytopenia after cessation of therapy have Differential diagnosis
been reported. Other haemostasis disorders that cause mucosal sur-
face bleeding, such as IMTP, warfarin toxicosis and
Prognosis inherited or acquired platelet function defects, need
The prognosis depends on existing predisposing to be considered.
causes. If IMTP is secondary to lymphoma, the
prognosis is poor. Idiopathic cases and those sec- Diagnosis
ondary to drug administration often respond to A diagnosis of DIC is usually accomplished when
therapy. Laminitis is a risk when using high doses of several supportive laboratory features are present in
corticosteroids. an animal that has a serious illness associated with