CS - Bleeding Flashcards
3 responses of injury to blood vessel
- vasoconstriction
- collagen exposure
- tissue factor
What does tissue factor do?
initiates extrinsic pathway
What initiates intrinsic pathway?
collagen exposure
What does collagen exposure lead to?
- PLT activation
- intrinsic pathway
What is needed for platelet plug?
- platelet activation leading to platelet adhesion and aggregation
- vasoconstriction
What is the final common pathway?
- result of intrinsic and extrinsic pathways
- culminates in thrombin conversion to fibrin to fibrin clot with PLT plug
How can extrinsic pathway be measured?
PT
How can the intrinsic pathway be measured?
PTT
What causes thrombin inactivation? 3
- antithrombin
- tissue factor pathway inhibitor
- activated C-protein S
Signs - hypovolaemic shock/ hypoperfusion
- slow CRT
- white MM
- Tx : shock bolus of isotonic crystalloid
What does a weak peripheral pulse suggest?
hypovolaemia (anaemia causes bounding pulse)
What aspects of CBC suggest an anaemia is regenerative?
- increased MCV
- decreased MCHC
- increased reticulocytes
- increased RDW
- confirmed by polychromasia on blood smear
What can suggest a peripheral cause for thrombocytopaenia?
megakaryocytes (e.g. destruction, consumption)
What are the types of thrombocytopaenia?
- PRIMARY: reduced platelets, clotting factors normal
- SECONDARY: reduced clotting factors, platelets normal
Types of Immune- Mediated Thrombocytopaenia (IMTP)
- PRIMARY/ IDIOPATHIC: commonly diagnosed as no other cause can be identified
- SECONDARY: if other causes of the TP can be found, e.g. parasites, neoplasia, infection, drug hx
Tx - immune mediated thrombocytopaenia
- cage rest to minimise risk of trauma and haemorrhage
- IMMUNOSUPPRESSIVE TX:
- GLUCOCORTICOIDS: prednisolone, dexamethasone, may be gradually reduced when PLT count returns to normal but monitor for recurrence. If not responsive to GCs, give vincristine (reduces macrophage phagocytosis and stimulates thrombopoiesis) and human IVIG (saturates receptors on macrophages and monocytes decreasing phagocytosis of platelets)
How quickly should you give isotonic crystalloid at shock rate?
Give 25% rapidly, monitor response and give more as required
CS - parasitism with A.vasorum
- coagulopathy leading to hypovolemia
- respiratory signs
Tx - parasitism with A.vasorum
- Fenbendazole (off label)- Four 5 day courses at a high dose rate over 1-2 months
- Imidacloprid/moxidectin spot-on can be used as a single application but has a lower efficacy than Fenbendazole
- moxidectin - single dose monthly
- milbemycin - weekly for 4 weeks
- Advise cage rest to reduce the risk of a parasitic embolism following treatment
- Oxygen to support
What is TS a measure of?
plasma proteins (albumin, globulins and fibrinogen)
What does reduced TS mean?
some form of protein loss
Why shouldn’t you give shock dose of FWB?
risk of intravascular haemolysis
Normal PCV range
37-55%
Normal TS range
55-70g/L
What is Drontal?
praziquantel, pyrantel embonate and febante
Which clotting factor has the shortest half life?
factor 7
How do rodenticides affect clotting?
block enzyme vit K1 reductase which converts vit K from inactive to active form, thus deficiency of active vit K thus devoid of clotting factors 2, 7, 9, 10)
How long does it take for onset of clinical signs of rodenticide poisoning?
27-72 hours (i.e. time for original CFs to be used up)
Tx of rodenticide poisoning
- EMETIC for recent ingestion (apomorphine for dogs, xylazine for cats)
- activated charcoal or sorbitol to bind toxin and prevent absorption
- vitamin K (not antidote but ensures sustained CF production)
- thoracocentesis
- blood transfusion (WB or FFP to replace CFs)
