Lesson 83 - Common Coagulation Disorders

What are the steps of primary hemostasis?

1. endothelial damage

2. exposure of collagen

3. activation and adhesion of platelets

What are the steps of secondary hemostasis?

1. activation of coagulation cascade

2. intrinsic, extrinsic, common pathway

3. clot is formed

What is the step of tertiary hemostasis?

fibrinolysis

If you suspect a platelet issue what is the first thing you want to check?

platelet count

If you suspect a platelet issue and you've already checked the count, what do you want to check next?

platelet function

What can cause an abnormal BMBT test?

1. thrombocytopenia

2. platelet dysfunction (thrombocytopathia)

What is a normal BMBT result?

max 3 minutes for clot to form

What test do we run to assess platelet function?

1. platelet function assay

2. BMBT (less sensitive)

What do we have to check first before running a PFA?

platelet count

What can affect the platelet function assay?

1. von Willibrand Disease

2. Aspirin therapy

What are the tests for a primary hemostasis disorder?

1. blood smear

2. platelet count

3. BMBT

4. PFA

What are the tests for a secondary hemostasis disorder?

1. ACT

2. OSPT

3. APTT

What are some other tests for coagulation?

1. FDPs

2. D-dimers

3. thromboelastography

What pathways does ACT evaluate?

1. intrinsic

2. common

What can cause a prolonged ACT?

1. hemophilias

2. rodenticides

3. DIC

4. liver disease

What pathway does PT/OSPT evaluate?

extrinsic

What can cause prolonged PT?

1. rodenticide

2. DIC

3. +/- liver disease

What pathway does the PTT/APTT test evaluate?

intrinsic

What can cause a prolonged APTT?

1. hemophilia

2. rodenticide

3. DIC

4. liver disease

What are FDPs and D-dimers used to evaluate?

systemic fibrinolysis

What could cause a positive FDP and D-dimer?

DIC

What are the vitamin K dependent factors?

1. II

2. VII

3. IX

4. X

What is the half-life of factor VII?

4-6 hours

What is the half-life of factor V, VIII, IX, X?

12-24 hours

What is the half-life of factor I, II, XI, XII?

2-3 days

What are the signs of primary hemostasis disorders?

1. surface bleeds

2. petechia, ecchymosis

3. melena

4. epistaxis

What are the signs of secondary hemostasis disorders?

1. cavity bleeds

2. hemothorax

3. hemoabdomen

What are some primary hemostatic defects?

1. not enough platelets

2. platelets not working

3. vascular disorder

What are some secondary hemostatic defects?

1. vitamin K problem

2. coagulation factor deficiency

What is the Virchows Triad?

1. blood stasis

2. endothelial damage

3. hypercoagulable state

A prolonged PT with a normal aPTT most likely indicates a defect in which pathway?

extrinsic pathway

A prolonged aPTT with normal PT suggests a defect in?

intrinsic pathway

What factor is deficient in hemophilia A?

Factor VIII

What factor is deficient in Hemophilia B?

Factor IX

What factor is deficient in Hemophilia C?

Factor XI

What factor is deficient in cats with Hageman factor deficiency?

Factor XII

What test would be affected with any of the hemophilia factor deficiencies?

prolonged aPTT

A 3-year-old dog presents with petechiae and gingival bleeding. Platelet count is 20,000/µL (low). PT and aPTT are normal. What is the most likely diagnosis?

Immune-mediated thrombocytopenia

A dog presents with prolonged bleeding after nail trimming. Platelet count is normal, PT and aPTT are normal, but BMBT is prolonged. What is the most likely diagnosis?

von Willibrand Disease

A cat presents with dyspnea and suspected pulmonary hemorrhage. PT and aPTT are both prolonged. Platelets are mildly decreased. The cat has possible rodenticide exposure. What is the underlying problem?

Vitamin K antagonism

A young male dog has recurrent joint swelling and hematomas. Platelet count and BMBT are normal, but aPTT is prolonged. PT is normal. What is the most likely condition?

Hemophilia A or B

A septic dog presents with bleeding from catheter sites. Lab results show thrombocytopenia, prolonged PT and aPTT, and elevated D-dimers. What is the most likely diagnosis?

Disseminated intravascular coagulation

A dog presents after trauma with large hematomas. Platelet count is normal. PT and aPTT are both prolonged. What pathway is affected?

Common pathway

A client presents a dog with suspected warfarin toxicity after possible rodenticide ingestion. The dog is mildly lethargic with no active bleeding. PT is prolonged, aPTT is normal. The owner has a very limited budget. What is the most appropriate initial treatment plan?

Start vitamin K1 therapy orally and monitor PT

What tests would you choose to use for warfarin toxicity?

PT and PTT

A dog is suspected of anticoagulant rodenticide toxicity 12 hours after ingestion. Coagulation tests (PT and aPTT) are still within normal limits. Which of the following best explains this finding?

Warfarin does not affect circulating clotting factors already present

What breeds have inherited platelet function abnormalities?

1. cocker spaniels

2. otterhounds

3. great pyrenees

4. bassett hounds

5. cats

Why is platelet function affected with von Willibrand Disease?

1. vMB factor is deficient

2. platelets can't adhese

What can cause acquired thrombopathies?

1. drugs

2. uremia

3. liver disease

4. dysproteinemias

A 9-year-old cat with chronic kidney disease presents with oral ulceration and intermittent gingival bleeding. Laboratory results show normal platelet count, normal PT and aPTT, but prolonged buccal mucosal bleeding time (BMBT). What is the most likely cause of the bleeding disorder?

Uremia-induced platelet dysfunction

What drugs cause platelet function abnormalities?

1. aspirin

2. carprofen

3. some antimicrobials

What are the causes of thrombocytopathias?

1. hereditary

2. drugs

3. vaccines

4. uremia

5. monoclonal gammopathies

A young dog presents with recurrent epistaxis and prolonged bleeding after minor injuries. Laboratory testing reveals a normal platelet count, normal PT and aPTT, but markedly prolonged buccal mucosal bleeding time (BMBT). Platelet aggregation testing shows failure to aggregate in response to ADP and collagen. What is the most likely underlying defect?

Defect in platelet glycoprotein IIb/IIIa receptors

A young dog presents with recurrent epistaxis and prolonged bleeding after minor injuries. Laboratory testing reveals a normal platelet count, normal PT and aPTT, but markedly prolonged buccal mucosal bleeding time (BMBT). Platelet aggregation testing shows failure to aggregate in response to ADP and collagen. What disorder does this dog have?

Glanzmann thrombasthenia

A 6-month-old puppy presents with recurrent nosebleeds and mild bruising. Lab results show a low-normal platelet count, prolonged buccal mucosal bleeding time, normal PT and aPTT. Platelets seem to have an issue with adhesion. You run a von Willibrand factor test and it shows normal amounts of vWF. What is the most likely defect?

Deficiency of platelet glycoprotein Ib complex

A 6-month-old puppy presents with recurrent nosebleeds and mild bruising. Lab results show a low-normal platelet count, prolonged buccal mucosal bleeding time, normal PT and aPTT. Platelets seem to have an issue with adhesion. You run a von Willibrand factor test and it shows normal amounts of vWF. What syndrome does this dog have?

Bernard-Soulier syndrome

What tests would be affected by a thrombocytopenia and what would the result be?

1. prolonged BMBT

2. decreased platelets

What tests would be affected by a thrombocytopathia and what would the result be?

1. prolonged BMBT

2. affected platelet function assay

What tests would be affected by vWD and what would the result be?

1. prolonged BMBT

2. normal to prolonged ACT

3. normal to prolonged PTT

A dog is diagnosed with severe von Willibrand Disease. Laboratory tests show prolonged bleeding time and a mildly prolonged aPTT. Which of the following best explains the prolonged aPTT?

vWF normally stabilized circulating factor VIII, and its deficiency reduces factor VIII levels

What tests would be affected by hemophilias and what would the result be?

1. prolonged ACT

2. prolonged aPTT

What tests would be affected by rodenticide poisoning and what would the result be?

1. normal to prolonged BMBT

2. prolonged ACT

3. prolonged PT

4. prolonged PTT

5. normal to decreased platelets

6. normal to decreased fibrinogen

7. normal to increased FDPs

What tests would be affected by DIC and what would the results be?

1. prolonged BMBT

2. prolonged ACT

3. prolonged PT

4. prolonged PTT

5. decreased platelets

6. decreased fibrinogen

7. increased FDPs

What tests would be affected by liver disease and what would the results be?

1. normal to prolonged BMBT

2. prolonged ACT

3. normal to prolonged PT

4. prolonged PTT

5. normal to decreased platelets

6. normal to decreased fibrinogen

What is the most common inherited bleeding disorder in dogs?

von Willebrands disease

What is Type 1 vWD?

1. low concentration of normal vWF

2. Doberman Pinschers

What is Type II vWD?

1. low concentration and abnormal vWF

2. german shorthaired pointer

3. german wirehaired pointer

What is type III vWD?

1. abscence of vWF

2. dutch kooiker

3. scottish terrier

4. shetland sheepdog

When is vWDs usually diagnosed?

1. most do not bleed spontaneously

2. bleed excessively during/after surgery

3. bleeding during teething or estrus

What are tests that we can use for a definitive diagnosis of vWD?

1. quantification of vWF

2. genetic testing

What blood products can be used for vWD?

1. FFP preferred

2. whole fresh blood as second option

3. platelet concentrate as third option

4. cryoprecipitate as fourth option

A doberman is about to undergo surgery but it has a history of type 1 von Willibrand Disease. What could we give before surgery to prevent bleeding in this patient?

desmopressin acetate

What is the effect of desmopressin acetate?

causes massive release of vWF from endothelial cells

What patients is desmopressin acetate not effective in?

dogs with type 2 or 3 vWD

What are some examples of some vitamin K antagonists?

diphacinone, brodifacoum, bromadiolone, warfarin

What are some less common causes of vitamin K deficiency?

1. malabsorption due to obstructive cholestasis

2. infiltrative intestinal disease

3. liver disease

What is the pathogenesis of vitamin K antagonism from rodenticide?

1. inhibits vitamin K epoxide reductase

2. vitamin K cannot be reduced to its active form

3. coag factors cannot be activated

When do cats typically get rodenticide poisoning?

rare but can have relay toxicosis from ingested prey

What clinical signs are seen with rodenticide poisoning?

1. acute collapse

2. coughing, thoracic pain, dyspnea

3. pale mucous membranes

4. hematomas

5. bleeding into body cavities

What is a test that is unique to vitamin K antagonism?

PIVKA

What are the main treatments for rodenticide toxicity?

1. vitamin K1 therapy (Phytonadione)

2. emesis if recent enough

3. blood transfusions

4. supportive care with fluids

How do we administer phytonadione?

1. subcutaneous

2. multiple sites with small gauge needle

3. oral once dog is stable and eating

4. long term therapy required

What is the prognosis of rodenticide toxicity?

good if caught early and treated long enough

What are some vitamin K antagonists that are common in large animals?

1. moldy sweet clover

2. warfarin

What are some inherited bleeding disorders in large animals?

1. hemophilia A

2. vWF deficiency

3. preka lekrien deficiency

What signalment associates with hemophilia A?

1. german shepherd

2. males only

What horse breeds are associated with preka lekrien deficiency?

1. belgians

2. minis

What are some clinical signs of DIC in horses?

1. petechial or ecchymotic hemorrhages

2. bleeding from venipuncture sites or epistaxis

3. microthrombi (renal, thrombophlebitis, laminitis)

What is the only test that can tell information about hypercoagulability?

thormboelastography

What diseases invoke Virchows triad?

1. heart diseases like heart failure, enlargement, valvular disease

2. diseases that cause systemic, massive vasculitis

3. hypercoagulable state

What diseases cause massive systemic vasculitis?

1. pancreatitis

2. IMHA

3. SIRS/sepsis

4. heat stroke

5. leptospirosis

What diseases can cause a hypercoagulable state?

1. hyperadrenocorticism

2. protein-losing nephropathy

3. protein-losing enteropathy

What are the common patient presentations with Virchows triad?

1. cats with saddle thrombus secondary to heart disease

2. pulmonary thromboembolism

3. CBC shows platelet consumption

4. TEG and D-dimers consistent with hypercoagulable state

A 9-year-old cat presents acutely with hind limb paralysis, cold and painful paws, and absent femoral pulses. The cat has a history of chronic heart murmur and recent lethargy. What is the most likely underlying cause of the thrombus?

hypertrophic cardiomyopathy-associated thromboembolism

What diagnostics would you run for a thrombus that is caused by heart disease?

1. radiographs

2. ECG

3. echo

4. physical exam

A 10-year-old dog presents with sudden onset of dyspnea and coughing. Physical exam reveals tachypnea, mild tachycardia, and abdominal enlargement. The dog has a history of polyuria, polydipsia, and a pot bellied appearance. Thoracic imaging shows pulmonary thromboembolism. Which of the following is the most likely underlying cause of the thrombus?

hyperadrenocorticism causing hypercoagulability

A 7-year old dog presents with acute vomiting, abdominal pain, and lethargy. On physical exam, the dog is tachycardic, dehydrated, and has pale mucous membranes. Biochemistry shows elevated pancreatic lipase and mild hyperbilirubinemia. The dog develops dyspnea and hypoxemia in the hospital. Imaging shows pulmonary thromboembolism. Which of the following is the most likely pathophysiologic mechanism for the thrombus?

pancreatitis creating a hypercoagulable state from systemic inflammation

A 6-year-old dog presents acutely with swelling and dark discoloration of the tongue, drooling, and difficulty eating. The dog also has vomiting, jaundice, and lethargy. Biochemistry shows elevated BUN/creatinine and mildly elevated liver enzymes. Which of the following is the most likely underlying cause of the lingual thrombus?

endothelial damage and consumptive coagulopathy from leptospirosis

A 7-year-old dog presents with acute hind limb weakness, cold paws, and absent femoral pulses. The owner reports a history of chronic proteinuria, mild edema, and weight loss. Laboratory findings show hypoalbuminemia, hypercholesterolemia and proteinuria. Which of the following is the most likely underlying cause of the thrombus?

hypercoagulability secondary to protein-losing nephropathy

A 6-year-old dog presents with acute hind limb weakness, cold paws, and absent femoral pulses. The owner reports a history of chronic diarrhea, weight loss, and ascites. Laboratory findings show hypoalbuminemia and hypocholesterolemia. Which of the following is the most likely underlying cause of the thrombus?

hypercoagulability secondary to protein-losing enteropathy