Felis ISSN 2398-2950

Anesthesia: in bleeding disorders

Contributor(s): Graham Bilbrough, Jeff Ko

Introduction

Assessment and pre-operative examinations

  • Bleeding disorders are either acquired   Hemostatic disorders: acquired  or congenital   Hemostatic disorders: inherited  . The most common congenital bleeding disorders are von Willebrand's disease and hemophilia in dogs and hemophilia in cats.
  • Clinically, there is a difference in the manifestation of coagulopathy and platelet defects. Coagulopathy tends to have delayed hemorrhage after initial injury and persistent bleeding into deep layers of muscles and joints, whereas with platelet defects bleeding usually occurs immediately after injury and frequently involves blood oozing and seeping into the mucous membrane and skin.
  • Physical examination may reveal prolonged bleeding of the skin or mucosal surfaces. The history may also indicate excessive bleeding following intravenous catheterization, hematoma after trauma, abnormal bleeding or recurrent spontaneous bleeding during and/or after surgery.
  • Confirm an abnormal tendency to bleed by conducting laboratory tests.
  • Abnormal platelet function and numbers can be detected using buccal mucosal bleeding   Buccal mucosal bleeding time   and platelet counts   Hematology: platelet count  :
    • a. Normal buccal mucosal bleeding time in dogs and cats is between 2-4 minutes.
    • b. Normal toe nail bleeding time in dogs and cats is between 2-6 minutes.
    • c. A normal platelet count in dogs and cats is between 150,000 to 700,000/mm3. Values below 100,000/mm3 are likely to result in prolonged bleeding times.
    • d. In cats, platelet clumping is a commonly occurring problem regardless of how well the samples are collected. Platelet clumping in cats prevents accurate counts of the platelets and is likely to cause erroneous report by either machine or manually. In dogs, platelet clumping is less of a problem than that observed in cats.
  • Extrinsic pathway and common pathway defects can be tested by measuring prothrombin time (PT)   Hematology: prothrombin time  . Most extrinsic pathway defects are acquired and frequently involve factor VII   Factor XII deficiency  . This usually results from vitamin K interference or deficiency. Rodenticide toxicity   Anticoagulant rodenticide poisoning  in dogs and cats can also cause significant prolonged PT. Normal PT is between 5 to 7 seconds. A PT longer than 1.5 times normal range together with clinical history of abnormal systemic bleeding   →    rodenticide should be suspected.
  • Intrinsic and common pathway defects can be tested by measuring APTT (activated partial thromboplastin time   Hematology: activated partial thromboplastin time  ) and ACT (activated clotting time   Hematology: activated clotting time  ). However, ACT does not distinguish between platelet deficiency/dysfunction and defect in the appropriate coagulation factors. It may be desirable to measure the concentration of the individual coagulation factors to determine the exact cause and thus determine the most appropriate blood product.
  • Normal APPT is between 11-20 seconds. An intrinsic pathway defect is usually an inherited disorder with at least one defect existing in factor VIII, IX, XI,  or XII.
  • Thrombin clotting time can be used to test for deficiency or dysfunction of fibrinogen.
  • Assays detect von Willbrands (vW) disease and determine the significance as type 1, 2, or 3. Type 1 vW disease is characterized by low plasma vW factor with normal protein structure. Type 2 vW disease is typically associated with a low vW factor concentration and an abnormal protein structure.  Type 3 vW disease is a complete vW factor deficiency where the concentration of the factor in plasma is undetectable.
  • Breed disposition for Type I vW disease is most prevalent in Airedale, Akita, dachshund, Doberman pinscher, German shepherd, golden retriever, greyhound, Irish wolfhound, Manchester terrier, Pembroke Welsh corgi, poodle, mixed breeds, other dog breeds, Himalayan cats. Type 2 vW disease is more prevalent in German shorthaired pointer and German wirehaired pointer. Type 3 vW disease tends to occur in Dutch Kooikerhondje, Scottish terrier, Shetland sheepdog, and mixed breeds.
  • Hemophilia A is characterized by a deficiency of coagulation factor VIII and hemophilia B is a deficiency of coagulation factor IX in dogs and cats.

Clinical preparation and management

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Anesthetic management

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Wingfield W E, Van Pelt D (1989) Abnormal bleeding. Vet Clin North Am Small Anim Pract 19 (6), 1275-1286 PubMed.
  • Johnson C S, Turrentine M A, Kraus K H (1988) Canine von Willebrand's disease. A heterogeneous group of bleeding disorders. Vet Clin North Am Small Anim Pract 18 (1), 195-229 PubMed.
  • Angelos M G, Hamilton G C (1986) Coagulation studies: prothrombin time, partial thromboplastin time, bleeding time. Emer Med Clin North Am (1), 95-113 PubMed.
  • Sampson J F, Hamstra R, Aldrete J A (1979) Management of hemophiliac patients undergoing surgical procedures. Anesth Analg 58 (2), 133-135 PubMed.

Other sources of information

  • Brooks M (1999) Hereditary bleeding disorders in dogs and cats. Vet Med 555-564.


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