Page 1575 - Cote clinical veterinary advisor dogs and cats 4th

790.e6 Platelet Dysfunction

○ Clot retraction • Administer preoperative transfusion to supply list of abnormal bleeding for any young
○ Platelet aggregation and secretion studies For prophylactic treatment: dog or cat after common disorders (e.g.,
platelets.
VetBooks.ir • Genetic mutation detection test (basset • Give platelet-rich plasma to animals with • Platelets stick to glass, including the inside of
○ Flow cytometry
thrombocytopenia, von Willebrand disease,
coagulopathies) have been ruled out.
○ Electron microscopy
clinically severe hereditary platelet function
hound, Landseer Newfoundland, spitz,
otterhound, Great Pyrenees, German disorders (i.e., showing or having shown overt anticoagulant-filled blood collection bottles,
clinical signs of bleeding) before any surgical
and whole blood given to replace platelets
shepherd) procedure. should be collected in plastic blood bags.
• Consider additional transfusion(s) at 2- to • The differential diagnoses for animals with
TREATMENT 8-hour intervals; they may be needed for persistent bleeding and a normal platelet
major surgery or if excessive hemorrhage is count, normal PT, and normal aPTT
Treatment Overview noted. should include platelet function defects, von
• Control active bleeding with medical or • Administer desmopressin acetate (DDAVP; Willebrand disease, fibrinolytic defects, and
transfusion therapy, as needed. 1 mcg/kg SQ); it may be sufficient to prevent diseased or damaged blood vessels.
• Avoid invasive procedures pending correction abnormal bleeding due to acquired platelet
of acquired disease (or transfusion). dysfunction if invasive procedures must be Technician Tips
○ For an acquired dysfunction performed. The need for additional transfu- Dogs and cats with platelet dysfunction are at
Identify and correct underlying disease sions is based on falling hematocrit and/or risk for abnormal hemorrhage at venipuncture
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condition. abnormal bleeding from the surgical site. and at catheter sites. As a general rule, peripheral
Discontinue or substitute drug therapy. veins (not the jugular vein) should be used for
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Transfusion to correct anemia (platelet Behavior/Exercise venous access.
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transfusion rarely needed) Dogs and cats with hereditary thrombopathias
○ For a hereditary dysfunction should be managed to prevent injuries (e.g., no Client Education
Transfuse sufficient platelets to support access to sharp toys or bones, no unobserved • Owners should avoid giving dietary supple-
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hemostasis if bleeding is severe. outside activity). ments containing fish oils or plant alkaloids
to any pet with acquired or hereditary platelet
Acute General Treatment Drug Interactions dysfunction.
• Control superficial sites of hemorrhage Judicious use or avoidance of drugs with anti- • Platelet function testing and/or mutation
(gingival or cutaneous wounds). platelet or anticoagulant effects (e.g., NSAIDs, detection tests may be indicated (before
○ Direct pressure, wound glue, suture, sulfonamides, heparin, warfarin, clopidogrel, breeding or surgery) for breeds or lines with
bandage plasma expanders, cytotoxic drugs, estrogens) high prevalence of hereditary thrombopathias.
• Replace red blood cells (RBCs) for severe
blood loss anemia (p. 1169). Adjust initial Recommended Monitoring SUGGESTED READING
doses based on hematocrit and ongoing loss. • Physical exam to monitor external blood loss, Boudreaux M: Characteristics, diagnosis, and treat-
○ Fresh whole blood (e.g., 12-20 mL/kg IV) petechiae/ecchymoses, membrane color ment of inherited platelet disorders in mammals. J
○ Packed RBCs (e.g., 6-12 mL/kg IV) • Serial hematocrit and plasma protein Am Vet Med Assoc 233:1251-1259, 2008.
• Initiate platelet replacement to control determinations to help identify internal or
systemic bleeding. Platelet-rich plasma has chronic hemorrhage ADDITIONAL SUGGESTED
a short shelf life (days) and is less widely READING
available and more expensive than other PROGNOSIS & OUTCOME Brooks MB, et al: Platelet disorders and von
blood components. The half-life of transfused Willebrand disease. In Ettinger S, et al, editors:
platelets is shorter than the half-life of RBCs, • Acquired dysfunction: good prognosis if Textbook of veterinary internal medicine, ed 6,
but it is still longer than most clotting factors underlying disease or drug therapy is reversed St. Louis, 2004, Elsevier, pp 1918-1929.
and von Willebrand factor. A single platelet- • Hereditary dysfunction Callan MB, et al: Immune-mediated thrombocyto-
rich plasma (PRP) transfusion may supply ○ Depends on severity of defect penia, von Willebrand disease and other platelet
sufficient platelets to form a hemostatic plug; ○ Repeated transfusions are required to disorders. In Ettinger S, et al, editors: Textbook
in vivo half-life is not necessarily a limitation maintain patients with severe defects. of veterinary internal medicine, ed 8, St. Louis,
2017, Elsevier, p. 847.
of the product. ○ Transfusion is typically required for any
○ Fresh whole blood (12-20 mL/kg IV) major surgical or traumatic injury. AUTHOR: Marjory B. Brooks, DVM, DACVIM
○ Platelet-rich plasma (6-12 mL/kg IV; >5 EDITOR: Jonathan E. Fogle, DVM, PhD, DACVIM
9
× 10 plat/kg IV) PEARLS & CONSIDERATIONS
○ StablePlate RX (BodeVet) is a new
lyophilized platelet-derived product that Comments
may provide short-term hemostasis for • Acquired platelet dysfunction is common but
acute thrombopathic hemorrhage. rarely causes severe spontaneous hemorrhage.
• Consider antifibrinolytic agents (e.g., amino- Animals that are bleeding severely should
caproic acid 50-100 mg/kg q 8h; tranexamic be evaluated for other potential underly-
acid 10-20 mg/kg q 8h) as adjunct therapy ing causes (e.g., anticoagulant rodenticide
to control active hemorrhage. intoxication, severe thrombocytopenia,
disseminated intravascular coagulation).
Chronic Treatment • Hereditary platelet dysfunction is relatively
For hereditary dysfunction: uncommon but is likely underdiagnosed
• Avoid invasive procedures unless essential. because of the need for referral to document
• Do not administer drugs with antiplatelet and classify specific traits. Platelet dysfunc-
effects. tion belongs on the differential diagnosis

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