Treatment of coagulopathies Flashcards
(38 cards)
Treatment of immune mediated haemolytic anaemia
Immunosupression
- glucocorticoids (reduces chemotaxis and endothelial adhesion, reduces arachidonic acid release, reduced T cell activation, suppersses cytokine production and macrophage activity)
- Ciclosporin (calcineurin inhibitor, inhibits T-cell activation, proliferation, and IL-2)
- Azathioprine (inhibits purine biosynthesis- humoral immunity)
- Mycophenolate (inhibits purine synthesis, alternative to azathioprine)
- IV immunoglobulin
Tansfusion if severely affected
Side effects of glucocorticoids
Common
Iatrogenic hyperadrenocorticim
PUPD
Polyphagia
Muscle weakness/wasting
Poor hair growth
Skin thinning
Elevated liver enzymes (esp ALP)
Diabetogenic
Can increase the risk of secondary infections (UTIs, skin infections)
What is the risk of combining NSAIDs and corticosteroids?
GI ulceration
Main indications for using alterantive immunosuppressive agents
Absolute contraindication for use of glucocorticoids, meaning others can be used as first line
Failure of treatment with glucocorticoids
‘Steroid sparing’ to reduce the dose of glucocorticoids needed/taper them off more quickly - due to side effects, either present or anticipated
Severe disease to ensure that effective treatment is not delayed
Ciclosporin
Calcineurin inhibitor, inhibits T cell activation, proliferation, and secretion of IL-2
Immunosuppression takes 1-2 wees to be fully effective
Not myelosuppressive
Expensive!
Severe side effects uncommon, can cause V+ and D+ (mild and transient)
Hypertrichosis common
Can also cause gingival hyperplasia and nephrotoxicity
Azathioprine
Not licensed
Can cause severe bone marrow suppression in cats - use is not recommended
Purine analogue
Acts on humoral mediated immunity
Adverse effects: bone marrow suppression, hepatotoxicity
Monitored with routine haem and biochem every 1-2weeks initially and then every 1-2mo
Can take several weeks to achiece adequate immunosuppression
Mycophenolate mofetil
Not licensed for use in dogs or cats
Inhibits purine systhesis, alternative to azathioprine
Main adverse effects: GI (nausea, vomiting, diarrhoea), can also cause bone marrow supression
Intravenous immunoglobulin (IVIG)
Not licensed in cats or dogs
Very expensive
Pooled human immunoglobulins
Act through macrophage Fc receptor signalling
Given as single transfusion
Beneficial in some cases with severe, refractory disease
Anti-thrombotic therapy in IMHA
Used off license
Thromboembolism is the most common cause of death in IMHA cases.
Improves outcomes - best therapy not known
Clopidogral unless thromboembolic disease has already occurred.
Thromboprophylaxis should be used in all dogs with IMHA unless they have severe thrombocytopenia (<30 x109 cells/l).
Possible anticoagulants for IMHA
Heparin - inhibits coagulation casacade via activation of anti-thrombin III, needs monitoring due to risk of coagulopathy
Rivaroxaban - direct Xa inhibitor, can be administered orally, less monitoring needed
Platelet inhibition in IMHA
Aspirin - NSAID, COX inhibition, prevents platelet activation. Risk of GI ulceration with high doses
Clopidogrel - inhibits ADP receptors on platelets, works as well as aspirin with less risk of GI ulceration
Immunosuppressive dose tapering and monitoring in IMHA
Length of treatment needed unknown
Reduce corticosteroid dose by about 25% every 3-4 weeks to stop medication after around 6mo
Any additional immunosuppressives should be stopped after the glucocorticoids unless cost or side effects inhibit
Need to monitor to ensure clinical remission is maintained - PCV/haematology - some will need ongoing immunosuppressive therapy
Thrombophylaxis should be continued until remission has been achieved and steroids stopped (or after 6mo)
What % of dogs relapse (IMHA)
About 15-20%
Either while on treatment or after treatment discontinued
After relapse dose tapering should be significantly slowed
Emergency assessment and treatment of clotting disorders
Point of care ultrasound to assess bleeding
PCV - will not immediately fall, important to assess
Serum total protein
Crystalloid or colloid fluid therapy to maintain circulating volume
Blood product transfusion
Treatment for immune mediated thrombocytopaenia
Braodly the same immunosuppressives as IMHA
No effective way to rapidly increase platelet counts - fresh whole blood has them but lifespan is short
Vincristine can also improve response (alongside steroids)
Mycophenolate can be used as a sole agent if glucocorticoids contraindicated
Prognosis good
Treatment of vonWillebrands disease
Depends on severity of signs
Use of drugs that inhibit platelet function should be avoided e.g. NSAIDs
Desmopressin used before surgery to increase vWF and reduce bleeding (for type 1 vWD)
Transfusion of cryoprecipitate or fresh frozen plasma will provide vWF in an emergency situation - can be used bfore surgery for dogs with severe type 2 or 3 vWD
Treatment for rodenticide toxicity
Parenteral, followed by enteral, vitamin K1 therapy, continued for at least 3-4 weeks
PT should be checked 36-48hrs after stopping treatment
Activation of vitamin K dependent factors will take several hours - only appropriate for stable, well dogs
Coagulation factors can be immediately replaced with frozen plasma
Treatment of Haemophilia A and B
Replacement of clotting factors using blood products when required
Angiostrongylus vasorum
Should always be considered in a coagulopathic dog
Signs: coughing, exercise intolerance, clotting defect
DIC or hyperfibrinolysis
Diagnosis: faecal testing, serology, ELISA SNAP (none 100% sensitive)
Treatment: moxidectin/imidacloprid (advacate), mibemycin/praziquantel (milbemax), fenbendazole (panacur)
Blood transfusions
Obtained through donation or from a blood bank
Provides RBCs and plasma
Second choice for IMHA after pRBCs (increases blood volume which you normally dont want in IMHA)
Currently no blood bank for cats
Packed Red Blood Cells
Does not contain clotting factors
Produced by blood bank (good screening of donors)
Can be combined with other components
Better for euvolaemic animals e.g. IMHA
Fresh whole blood
Includes red cells and clotting factors (and some platelets)
Collected in practice (faster, cheaper?)
Best for haemorrhage
When to consider transfusion
If PCV below 15-20% (20% if having GA/sedation)
Severity
Chronicity and rapidity
Existing co-morbidities
Physical examination findings (HR, pulse quality, degree of weakness/lethargy)
other markers of impaired oxygen delivery
safety for further interventions
Requirements for canine blood donors
Healthy, fully vaccinated, no travel, appropriate temperament
No previous transfusion
> 25kg dogs
1-8yo
Normal PCV: ideally >40%
Ideally DEA 1.1. negative
Collect aseptically into a closed blood giving set containing anticoagulant
