Equine anaemia Flashcards
(41 cards)
How does the PCV of cold blooded horses and ponies differ to TBs and hot-blooded horses?
Cold blooded, ponies = lower PCV (26-35%)
TB, hot blooded = higher PCV (35-45%)
What are some clinical signs expected from anaemia?
Lack of O2: Tachypnoea Tachycardia Pallor Exercise intolerance Lethargy Weakness and collapse Heart flow murmur
Why can anaemia lead to a heart flow murmur?
Decreased blood viscosity
Increased turbulence
How much blood is needed to be lost to go into hypovolaemic shock?
30%
What are the symptoms of hypovolaemic shock?
Tachycardia Tachypnoea Hypothermia Pale/dry mms Increased CRT Weak pulse Cold extremities
How can the amount of blood loss be estimated in horses?
Amount of buckets filled
Amount pouring in 30 seconds
What is the % of body weight that is blood volume? (Horses)
8%
How does a horse being overweight affect the % of BW that is blood volume?
Overweight horse, less % of BW is blood
<8%
In a 500kg horse, how many litres of blood is needed to go into hypovolaemic shock?
8% of BW = blood volume = 40L
30% needed for hypovolaemia = 12L
What clinical signs may accompany anaemia due to haemolysis in horses?
Fever
Icterus
Pigmenturia (yellow or red depending if intra/extravascular)
What clinical signs can signal chronic blood loss in horses?
Epistaxis
Haematuria
Melaena (rare as handgut fermenter)
The equine spleen acts as a reservoir for what blood components?
RBCs
Platelets (1/3 of total blood platelets in spleen)
What can increase the PCV of horses (non-pathological)?
Exercise
Excitement
What happens to horses during excitement that doesn’t happen in any other species?
Spleen contraction
reservoir of RBCs and platelets released
Describe the steps taken to diagnose anaemia in horses
History Clinical exam Acute or chronic External or internal blood loss Clotting disorder? Haemolysis? Lab assessment - all blood tests, RBC morphology etc
How does the spleen mask blood loss for several hours post haemorrhage?
Contracts - releases stored RBCs and platelets
What compensatory mechanism for blood loss in horses involve the endocrine system?
Release of catecholamines
Cause vasoconstriction, increase cardiac output
ADH secreted - increases reabsorption of water from renal tubules and GIT
What compensatory mechanisms does a horse use after blood loss?
Spleen injects stored RBCs into circulation
Catecholamines release causes increased vasoconstriction and CO
Fluid drawn from interstitium into plasma
Increased reabsorption of water in renal tubules and GI tract
After a significant bleed in horses, when can the decreased total protein and decreased PCV be detected?
TP = 4-6 hrs post injury PCV = 12-24hrs post haemorrhage (when plasma volume expansion > splenic compensation)
Reticulocytosis and polychromasia usually indicate regenerative anaemia. Are they seen in horses?
Rarely
Small nuclear remnants are occasionally found in RBCs of horses. What are they called? Do they indicate erythropoiesis?
Howell-Jolly bodies
No - normal finding
How can non-regenerative myeloid disorders be diagnosed in horses?
Bone marrow biopsy
If haemolysis is intravascular, what colour would the plasma be?
Pink
With haemolysis, how are total and indirect bilirubin concs affected?
Both elevated
