Overview

• Red blood cell count is a measure of the number of circulating red cells.
• Measured in (RBC) numbers x 10*12/l or 10e9/ul.
• Normally evaluated using automated cell counters.
• Variation between different breeds and types (also variation within types).
• Spleen normally retains 30% of RBC in a resting horse but these can be quickly released on exercise or excitement (including blood sampling!).
• Number of circulating red cells very labile.

Sampling

Tests

Methodologies

• Normally automatic cell counters used. Manual counting method using hemoccytmeter can be used if automated equipment is not available.

Availability

• Widely available at commercial laboratories.
• In-hospital testing.

Validity

Specificity

• 'Hot-blooded' breeds (eg Arabians   Arab  and Thoroughbreds   Thoroughbred  ) have higher RBC parameters than 'cold-blooded' breeds, eg native ponies   New Forest Pony    Dartmoor Pony    Shetland Pony  and draught horses   Irish Draught  . Vales for 'warm bloods' or crossbreeds may lie between lie between.

Technique (intrinsic) limitations

• Significant differences between ages (foal vs adult), breeds and types.
• Variation follows a normal distribution curve.
• Some normal individuals will have apparently abnormal results (and vice versa).
• Always interpret results in the light of clinical exmination.

Result Data

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Barrelet A (2004) Laboratory tests in equine practice Part 2: Haematological analyses. UK Vet 9 (8), 13-23.

Other sources of information

• Morris D D (1998) Diseases of the hemolymphatic System. In: Equine Internal Medicine. Eds: S M Reed and W M Bayly. W B Saunders, USA. pp 558-601.

Organisation(s)

• Veterinary commercial laboratories, State diagnostic laboratories or Veterinary College laboratories.