Page 1035 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1010 CHAPTER 9

VetBooks.ir circumstances and cannot be used to confirm the TRAUMATIC HAEMORRHAGE
presence of a regenerative response in isolation.
Therefore, evaluating serial haemograms tends Definition/overview
to be the best method for establishing the pres- Trauma to an area of the body that contains high
ence of a bone marrow response in the horse. concentrations of small blood vessels or a single
Examination of bone marrow aspirates or core large blood vessel often results in overt blood loss.
biopsies is another technique that can be used to The amount of blood lost determines morbidity and
facilitate this determination (Fig. 9.11). whether or not the animal will survive. Lacerations
of major arteries can result in severe hypovolaemic
shock and death within minutes.
9.11
Aetiology/pathophysiology
Trauma to vascularised tissue or laceration of major
blood vessels results in sometimes life-threaten-
ing haemorrhage. Rapid loss of large quantities of
blood may result in hypovolaemic shock and death.
Otherwise, animals will develop anaemia once
extravascular fluids move into the vascular space to
replace lost volume. Over the next several days to
weeks, erythrocytic hyperplasia in the bone marrow
will replace the RBC deficit, as long as haemorrhage
does not persist.

Fig. 9.11 Bone marrow aspirate from the horse Clinical presentation
in 9.10. The sample confirms that the anaemia Trauma is usually readily recognised and frequently
is regenerative, as indicated by the presence of includes overt cutaneous lesions. The source of
marked erythrocytic hyperplasia. Arrows indicate haemorrhage is often obvious. Other signs of trauma
developing nucleated RBCs and arrowheads indicate may include bruising and lameness. Internal haem-
polychromatophilic cells (Wright’s stain). orrhage into cavities, such as the thorax, abdomen or
uterus, may be less obvious (Fig. 9.12). Clinical signs
of blood loss depend on the volume of blood lost and
9.12 whether concurrent abnormalities are present. Pale
mucous membranes, tachycardia, tachypnoea, weak-
ness and lethargy are common.

Differential diagnosis
Haemorrhage from trauma must be distinguished
from other reasons for bleeding including coagulopa-
thy, disseminated intravascular coagulation (DIC),
neoplasia and immune-mediated thrombocytopenia
(IMTP).

Diagnosis
History and clinical signs are often sufficient to con-
Fig. 9.12 Severe haemothorax in a foal secondary to firm trauma as the cause of the haemorrhage. An
rib fractures. Note the size of the blood clot (arrow) estimation of blood loss should be performed when-
compared to the lung (arrowhead). ever possible, but care should be taken in interpreting