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Canine/feline anaemia (Diagnostic approach (History (Duration of CS,…

- - - - Stored at 4-6 degrees, fresh must be given within 8 hrs of collection and chilled lasts for 28 days (not platelets)
      - Used in anaemic AND hypoproteinaemic patients (haemorrhage)
    - - Lasts 42 days refrigerated
      - Most common indication is anaemia
    - - Contains coagulation factors and protein
      - Stored at -18 to -30 degrees for up to 1 yr. Defrost in water bath that is not > than 37 degrees
      - Indicated with coagulopathies, rodenticide toxicity, DIC, acute hypoproteinaemia
  - - - Acute: pyrexia, tachycardia, tachypnoea, hypotension, gallbladder oedema, +/- vomiting/diarrhoea/seizure
      - Delayed: transfused cells broken down over time (e.g. due to DEA 3, 5 and 7)
    - - Acute: air/blood clot emboli, citrate toxicity
      - Delayed: infectious disease due to contaminated blood products
- - - - Disorders of primary haemostasis (petechiae, ecchymosis, hyphema, epistaxis, haematuria, melaena)
        
        Vasculitis (bacterial toxins, viral infections, immune-mediated diseases such as SLE)
        
        Thrombocytopaenia
        
        Decreased production: drugs (oestrogen, PBZ, cyclophosphamide), infectious (FeLV, erlichiosis), secondary myelopthisis (neoplastic infiltration of bone marrow)
        
        Increased destruction: primary (Evan's syndrome, IMTP), secondary (drugs, infections, haemoparasites, neoplasia).
        
        Increased consumption: DIC, haemorrhage (typically platelets still > 100 x 10^9/L)
        
        Platelet dysfunction: congenital (rare), uraemia, severe liver disease, drug toxicity (aspirin, NSAIDs).
      - Disroders of secondary haemostasis (severe internal/external bleeding, bleeds deep into SC tissues, cavities and joints, epistaxis and haemoptysis).
        
        Clotting factor or vit K deficiency
        
        Rodenticide toxicity (prolonged PT, often normal aPTT), vWD disease (Dobermans!), severe liver failure, EPI (vit K is fat-soluble so is deficient with lipase deficiency), thrombocytopaenia
        
        Consumptive coagulopathies
        
        Heatstroke, snake bite, DIC/sepsis, massive blood loss
    - - Immune-mediated: IMHA (uncommon in cats)
      - Toxic: oxidative injury (Heinz bodies - onions, garlic, paracetamol, naphthalene, Zn toxicity)
      - Infectious: M. haemofelis, B. canis/gibsoni, E. canis
      - Microangiopathic: DIC, Caval syndrome, haemangiosarcoma, splenic torsion
- - - - Acute PCV drop < 20%, or chronic < 15%
      - Exercise intolerance, weakness, tachycardia, tachypnoea, dyspnoea, hypotension, syncope, stupor
      - Work up to 20 mL/kg/hr if tolerated. Transfuse complete volume within 4 hrs (prevents septicaemia).
- - - - Breakdown in immunotolerance, resulting in Ab-mediated destruction of RBCs (coated with IgG/IgM)
      - Primary (idiopathic): mainly dogs
      - Secondary (drugs, neoplasia, infections): mainly cats (assess for blood-borne parasites and viruses)
      - Most common cause of haemolysis in dogs
      - EVH (spleen) is most common, but IVH may occur
    - - Most common complication/cause of death is DIC/thromboembolism
      - EVH most common (splenomegaly)
      - Periods of acute haemolysis are associated with systemic inflammation (may allow disease progression)
    - - Typically acute-onset
      - Anorexia, pyrexia, weakness/lethargy, respiratory distress, collapse, pallor, icterus (rare in cats), vomiting/diarrhoea
    - - Cocker Spaniel, English Springer Spaniel, Poodle, miniature Schnauzer/Pinscher, Rough-Coated Collie, Bichon frise, Spitz
      - Female, young adult to middle-aged dogs
      - Overall rare in cats
    - - PE
        
        Tachycardia, tachypnoea, pallor/prolonged CRT, systolic murmur (due to hypoviscosity of blood), splenomegaly/hepatomegaly (+/- abdominal pain)
        
        If thrombocytopaenia (Evan's syndrome) then may see petechiae
      - Haematology/biochemistry
        
        Moderate/marked regenerative anaemia (corrected retic > 1%), decreased PVC with normal to elevated TP, inflammatory leukon (neutrophilia, monocytosis, +/- left shift and/or toxic change), thrombocytopaenia
        
        Hyperbilirubinaemia, high ALT
      - Blood smear
        
        Sparse RBCs, spherocytes (difficult to detect in cats), polychromasia, anisocytosis, macrocytosis, reticulocytes, nRBCs
      - Saline agglutination test
        
        Macro-/micro-agglutination
      - Coomb's test (DAT)
        
        Only perform if negative saline agglutination
        
        Detects Abs and complement on RBC surfaces
        
        Positive result supportive but negative result doesn't rule out (poor sensitivity). False -ves with glucocorticoids, incomplete washing of RBCs, low [Ab], complement on RBC surface
      - Coagulation testing
        
        Prolonged PT and aPTT - combination with thrombocytopaenia indicates DIC
      - Urinalysis
        
        Pigmenturia (haemoglobinuria), proteinuria, positive blood result on dipstick
    - - Prevention of haemolysis
        
        Prednisolone 1-2 mg/kg PO q12h
        
        If PO not tolerated, dexamethasone 0.1-0.3 mg/kg IV q12h
        
        Most dogs response within 7 days, but full effect may not be for 2-4 wks
        
        Additional immunosuppression
        
        Cats: chlorambucil, cyclophosphamide, cyclosporine
        
        Azathioprine contraindicated in cats due to risk of unacceptable adverse effects
      - Blood transfusion (not always)
        
        Indicated if PCV < 15% or acute drop < 20%, in conjunction with clinical signs (exercise intolerance, weakness, stupor, syncope, tachycardia, tachypnoea, dyspnoea, hypotension)
        
        1-2 mL/kg for first 20 mins and monitor for transfusion reaction (pyrexia, gallbladder oedema, +/- vomiting/diarrhoea, tachycardia, hypotension)
        
        5-10 mL/kg/hr (normovolaemic), 10-20 mL/kg/hr (hypovolaemic) and 4-5 mL/kg/hr (cardiac or renal disease). Transfuse whole amount of blood within 4 hrs (prevents septicaemia) with continual mixing of the bag (prevents citrate toxicity). Only saline can be run in the same IV line.
        
        pRBCs ideal (whole blood less ideal as plasma component may increase risk of transfusion reactions)
      - Thrombophylaxis
        
        Anti-platelet drugs (e.g. Clopidogrel) are common
        
        Clopidogrel: 1 mg/kg PO SID. Clinical effect within 2 days.
        
        Most dogs are in a hypercoagulable state (risk of thromboemboli)
      - Supportive care
        
        Oxygenation
        
        Gastric protectants (e.g. ranitidine, omeprazole)
        
        Fluid therapy (maintenance is 2-4 mL/kg/hr)
        
        Investigation and treatment of any causative underlying disease (e.g. doxycycline for tick-borne haemoparasites)
    - - Tick-paralysis, snake bite, pancreatitis, Addisonian crisis, DKA, internal haemorrhage/trauma (e.g. ruptured splenic haemangiosarcoma)
  - - - Prednisolone (0.5 mg/kg) most common
      - Phospholipase inhibition (anti-inflammatory effects)
      - Direct suppression of T cell function, and decreased interaction with B cells. Predominantly affects CMI.
      - Increased risk of thrombosis, especially with preexisting factors (IMHA)
      - Monitor liver enzymes, BG and renal function
    - - Inhibits T cell proliferation, but is also active against B cells
      - Lag period of 11 days before clinical effect
      - Often used in combination with glucocorticoids to allow more rapid dose reduction of glucocorticoids
      - Myelosuppression, pancreatitis, hepatopathy and GIT signs are major side-effects
    - - Blocks T cell activation
      - Licensed for treatment of atopic dermatitis in dogs - only immunosuppressive licensed for systemic use.
      - Transient GIT signs are major side-effect
    - - Not used for immunosuppression, but as adjunct therapy for IMTP
      - Binds to microtubulin in macrophages and inhibits phagocytosis of opsonised platelets
    - - Cytotoxic agent to resting and dividing cells, particularly to lymphocytes. Suppresses both humoral and CMI.
      - Primarily used as anti-cancer therapy
      - Myelosuppression an haemorrhagic cystitis are major side-effects
    - - Inhibits activation of T lymphocytes (via IL-2)
      - 10-100x more potent than cyclosporine
      - Majority of use is topical
      - Burning/pruritis with topical, GIT signs with systemic
    - - Not an immunosuppressive
      - Inhibits JK and subsequent formation of pro-inflammatory cytokines
      - Used to control pruritis in atopic dermatitis
    - - Not an immunosuppressive, but used as adjunct to animals in hypercoagulable states (e.g. IMHA, glucocorticoid therapy)
      - Inhibits platelets (via ADP)
    - - Mainly used for immune-mediated skin disease in cats
      - Cytotoxic, similar action to cyclophosphamide
      - Very slow onset of action
- - - - Diagnostic tests
        
        Platelet count
        
        BMBT (if platelets normal)
  - - - Diagnostic tests
        
        ACT (intrinsic and common - factors 7, 11, 9, 8, 10, 5, 2 and fibrinogen)
        
        PT (extrinsic and common - factors 3, 7, 10, 5, 2 and fibrinogen)
        
        aPTT (intrinsic and common - more sensitive than ACT)