IMHA SA

Primary vs secondary

·    Primary – no known trigger, usually inherited

·    Secondary – trigger/cause is underlying condition, e.g. infection, neoplasia, drugs/toxin/venom

o  More common in cats, triggered by FIP, Mycoplasma haemofelic, FeLV, chronic bacterial infections (e.g. severe dental disease, abscesses)

Clinical signs

·    Pyrexia

·    Pale MMs, jaundice

·    Cardiovascular abnormalities

·    Hepatomegaly (liver working hard to metabolise RBCs)

Diagnosis

·    Haematology – low PCV/HCT, reticulocytes, leucocytosis (neutrophilia +/- left shift)

o  +/- thrombocytopenia – can have IMHA + IMTP at same time (Evans syndrome)

·    Blood smear – spherocytes

·    Auto-agglutination test – 4 drops saline, 1 drop EDTA blood, looking for macroscopic agglutination (indicates ab on RBC surface)

·    Coombes test – identifies ab on RBC surface (more sensitive)

·    Biochemistry – incr. ALT/ALP (hepatocellular damage and cholestasis), discoloured plasma

·    Urinalysis – bilirubinuria, haemoglobinuria

Treatment

·    Treat underlying disease/trigger

·    Immunosuppression – glucocorticoids +/- cyclosporin, azanthioprine

·    Blood transfusion – RBCs will get haemolysed, but gives time for steroids to work, prevents patient dying of hypovolaemia or hypoxia during this time

·    Mycoplasma in cats – doxycycline

Potential consequences

·    Thromboembolic disease – blood is sticky and more likely to form cltos

·    DIC