Photo: Ayrial Foster, Berrimah Veterinary Laboratory NT
DESCRIPTION: Diffuse yellow discolouration of the atrioventricular valves and multifocal to coalescing red discolouration of the left ventricular endocardium in the sub-atrial region. Note the discolouration of the left papillary muscle in the region of attachment to chordae tendinae leading to the mitral valve. (The left papillary muscle is the single best sample to collect for histopathology in a grossly normal heart).
Dx: Regionally extensive endocardial haemorrhage and jaundice.
Actual case: Bovine with Anaplasma marginale infection.
Tip: Diagnosis of anaplasmosis is best made pre-mortem: blood smears showing intra-erythrocytic organisms and haematology showing anaemia. If the animal is found dead, a brain squash smear can be made by gently smearing a match-stick head sized piece of superficial cerebrum between two glass microscope slides.