Page 1047 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1022 CHAPTER 9

VetBooks.ir in adult horses and is most often associated with Differential diagnosis
The main differential is AID, which in rare circum-
chronic external blood loss.
Aetiology/pathophysiology stances can produce microcytic RBCs.
Chronic external blood loss, which can occur with Diagnosis
parasitism, bleeding GI ulcers, masses or coagulopa- The presence of a microcytic, hypochromic
thy, is the most common cause. Poor iron intake in anaemia is almost pathognomonic for iron defi-
neonates on a milk diet and without access to soil ciency. Serum iron is decreased and TIBC, which
may also result in iron-deficiency anaemia. is essentially a measure of transferrin, is normal
When iron stores become depleted, developing to increased. Bone marrow iron stores are usu-
RBCs in the bone marrow do not become fully hae- ally sparse or absent and the G:E ratio may be
moglobinised and may undergo additional cellular decreased due to accumulation of the later stages
division in an attempt to remain in the bone marrow of developing RBCs that cannot complete matura-
longer in order to complete haemoglobin formation. tion because of insufficient iron (Figs. 9.23, 9.24).
Initially, the bone marrow is able to respond to the Total protein concentration may be decreased
RBC deficit, but as iron becomes a limiting factor, with chronic external blood loss. Additional diag-
erythropoiesis becomes less efficient and eventually nostic testing should be directed at identifying the
lost red cells are not replaced, resulting in worsening reason for the iron deficiency.
anaemia.
Management
Clinical presentation The inciting cause should be identified and
Anaemia may be inapparent until severe. Lethargy, treated, if possible. Supplemental iron is required
exercise intolerance and pale mucous membranes are in the interim. Oral iron supplementation is pre-
common initial signs. Clinically evident haemorrhage ferred (ferrous sulphate 1.0–4.0 g/450 kg p/o
or parasitism may or may not be apparent. q24 h). If i/v iron supplementation is required,

9.23 9.24

Fig. 9.23 Bone marrow core biopsy from a Fig. 9.24 Bone marrow core biopsy from a horse with
horse with iron-deficiency anaemia. The lack of iron-deficiency anaemia. There are increased numbers of
blue staining indicates negative staining for iron late-developing erythrocytic cells (arrows) and no stainable
(Perl iron stain). iron. Polychromatophils are not present due to the lack of
iron required for complete maturation (H&E stain).