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Vet 165: Chapter 16, 17, 18 Recorded lecture

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💫 Short Summary

The video covers platelet evaluation methods, including counts, indices, and specialized tests. It discusses coagulation testing, clotting times, and rare laboratory tests. The mechanical and chemical phases of blood coagulation are explained, along with hemostasis disorders, factor deficiencies, and inherited coagulation disorders like von Willebrand disease in dogs. Additionally, it touches on thrombocytopenia, vitamin K deficiency, and disseminated intravascular coagulation. The segment also addresses obstructive shock and coagulation disorders, prompting viewers to identify the four vitamin K dependent factors.

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📊 Transcript
Platelet Evaluation Methods
00:35
The lecture explains platelet count, platelet indices, and platelet function tests.
Terms like thrombocytopenia and thrombocytosis are defined.
Platelet clumping can affect the accuracy of automated analyzer counts.
Freshly collected blood samples in EDTA should be used for platelet estimates.
Platelet counting methods and indices in blood analysis.
03:52
Platelet number can be calculated by counting per field or using white blood cell count.
Platelet indices like MPV and platelet crit are important for assessing platelet volume and blood composition.
Platelet distribution width (PDW) helps evaluate platelet size variations.
Additional evaluations such as reticulated platelet count and anti-platelet antibody assays are commonly done in referral laboratories for assessing platelet characteristics and responses.
The segment covers platelet evaluation, including counts, platelet clumping, and specialized laboratory tests like reticulated platelet count and anti-platelet antibody assays.
08:06
Coagulation testing is discussed to assess specific phases of the coagulation process and emphasizes the importance of determining coagulation status and platelet count.
The segment outlines the buccal mucosa bleeding time test procedure, highlighting the necessary supplies and steps for conducting the test in a clinical setting.
A video demonstration is mentioned for further understanding of the procedures discussed in the segment.
Viewers are prompted to assess test results through a question prompt provided in the segment.
Performing an Activated Clotting Time (ACT) Test.
12:38
The ACT test evaluates clotting factors except for factor seven, with normal values between 60 to 90 seconds.
Blood is collected in a vacutainer tube with additives triggering coagulation pathways.
The manual method involves pre-warming the tube, mixing the blood, and monitoring clot formation at specific intervals.
Severe thrombocytopenia and abnormalities in the intrinsic coagulation cascade can prolong ACT, while automated analyzers offer more efficient testing.
Overview of Coagulation Testing Process
17:31
The segment explains normal clotting times for dogs, horses, and cattle.
It details the partial thromboplastin time (PTT) and activated partial thromboplastin time (APTT) tests.
The intrinsic and extrinsic pathways of blood coagulation are discussed, emphasizing proteins and reactions involved.
Tissue factor's role in initiating blood clotting is highlighted, along with the importance of both pathways for blood coagulation.
Overview of prothrombin time test and clot retraction test for blood coagulation.
21:55
Prothrombin time test can be done with automated analyzers or manually with citrate plasma samples.
Clot retraction test evaluates platelet number and function of intrinsic and extrinsic pathways.
Intrinsic pathway involves proteins, cofactors, and enzymes, while extrinsic pathway is tissue-specific.
Both pathways are essential for blood coagulation, and results are recorded in the patient's chart after monitoring clot formation for 24 hours.
Rare tests in laboratory settings.
24:52
Fibrinogen determination and pivka testing are discussed for detecting vitamin K deficiency.
Pivka testing can differentiate rodenticide toxicity from hemophilia.
Fibrinogen degradation products are linked to liver failure, trauma, and hemangiosarcoma.
Fibrinolysis is mentioned as the natural breakdown of clots, providing insights into clotting function and potential health issues.
Overview of Blood Coagulation Process
30:21
Platelet adhesion and coagulation cascade are key components in blood coagulation.
Von Willebrand factor is important for stabilizing platelet clumps.
Coagulation cascade leads to the formation of fibrin strands which create the clot.
Understanding blood coagulation is crucial for managing coagulation factor deficiencies and maintaining blood vessel integrity.
Hemostasis disorders in dogs can be congenital or acquired and are often due to factor deficiencies, leading to symptoms like hemorrhages.
32:31
Common inherited coagulation disorders in dogs include hemophilia A, hemophilia B (Christmas disease), and von Willebrand disease.
Von Willebrand disease in dogs is caused by decreased production of von Willebrand factor, which is essential for platelet adhesion.
Von Willebrand disease commonly affects Dobermans and other canine breeds.
The disease has distinct forms based on inheritance patterns, with type one being autosomal dominant.
Different types of von Willebrand disease are categorized based on levels of circulating von Willebrand factor and their structure.
36:12
Types 2 and 3 of von Willebrand disease cause severe bleeding issues.
Thrombocytopenia, caused by factors like viral infections and medications, leads to a decrease in platelet count.
Vitamin K deficiency, often due to dietary conditions or bile duct obstructions, affects blood clotting factors synthesis.
Disseminated Intravascular Coagulation (DIC) is a coagulopathy secondary to other diseases like septic shock or trauma, leading to systemic hemorrhage or microvascular thrombosis.
Discussion on obstructive shock, DIC, and coagulation disorders.
40:11
Obstructive shock is related to DIC, which is a secondary result of shocks.
The segment raises a question about vitamin K dependent factors.
Viewers are prompted to identify the four factors that are vitamin K dependent.