Page 1048 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

H aemolymphatic system 1023

VetBooks.ir iron cacodylate (1 g/adult horse) should be given mechanisms are suspected, but the lesion is limited to
developing erythrocytes. With recombinant human
slowly. Iron dextran should not be administered
because of the high incidence of adverse reactions,
develops to the foreign protein, which cross-reacts
including anaphylaxis and death. Iron should erythropoietin administration, an immune response
not be administered to foals in the first 2 days of and removes both administered and endogenous
life. PCV should be monitored 1–3 times weekly erythropoietin.
during initial treatment. Serum iron and TIBC
should be evaluated every 2 weeks. Iron supple- Clinical presentation
mentation can be ceased when serum iron, TIBC In AA the animal is initially presented with pete-
and PCV are within reference intervals. Weeks of chial haemorrhages and epistaxis, or intermittent
supplementation may be required in severely iron- fever and weight loss, reflecting loss of platelets
depleted animals. and neutrophils, respectively. In PRCA the anae-
mia is usually moderate to severe and animals
Prognosis develop pallor, weakness, decreased exercise toler-
The prognosis is good if the reason for the iron ance and lethargy.
depletion can be discovered and eliminated.
Differential diagnosis
APLASTIC ANAEMIA AND Other causes of pancytopenia or non-regenerative
PURE RED CELL APLASIA anaemia, including iron deficiency and AID, should
be considered, although the latter tend to be less
Definition/overview severe.
Aplastic anaemia (AA) is a bone marrow stem-
cell disorder characterised by decreased produc- Diagnosis
tion of all blood cell types and replacement of Diagnosis is made by documenting haemato-
normal haematopoietic tissue with adipose tissue. logical abnormalities (pancytopenia with AA
Pure red cell aplasia (PRCA) is characterised by a and non-regenerative anaemia with PRCA) on
severe non-regenerative anaemia due to a deple- repeated CBCs, and examination of bone marrow
tion of developing erythrocytic precursors in the demonstrating marked hypoplasia to aplasia and
bone marrow. Leucocytes and platelets tend to be replacement with adipose tissue (AA) or severely
unaffected in PRCA. These diseases occur rarely decreased or absent developing erythrocytic pre-
in the horse. cursors (PRCA) (Figs. 9.25, 9.26).

Aetiology/pathophysiology Management
The inciting cause is often unknown, but immune- If an underlying disease process can be documented,
mediated phenomena and idiosyncratic drug reac- appropriate therapy should be administered.
tion should be considered. Most cases are idiopathic. Otherwise, supportive care, administration of broad-
Administration of recombinant human erythropoi- spectrum antibiotics and blood product transfusions
etin has also been reported to result in PRCA in are appropriate. Bone marrow transplantation could
horses. provide a cure but has not been evaluated and is not
In AA it is suspected that immune-mediated available for horses.
mechanisms are induced subsequent to exposure to
an infectious agent or drug. It is thought that anti- Prognosis
bodies develop to unknown antigens on the sur- The prognosis for AA or PRCA is generally guarded
face of developing stem cells in the bone marrow, to poor, but there may be a response to immunosup-
and these cells are removed, resulting in lack of pressive therapy. Recovery may take several weeks
production of mature cell types. In PRCA, similar to months.