Tests or procedures used by your vet to determine what is wrong with your horse, in order to reach a diagnosis.


Cytology, Cell Counts & Analysis of Fluid


Fluid normally bathes any body cavity, including the chest cavity, abdomen, joints, space around the spinal cord, etc.

For each of these fluid types, there is a normal range of characteristics and a normal population of cells. Diseases that involve these cavities change these characteristics and cell population. These changes are determined in a laboratory, and they tell veterinarians a great deal about the nature of a disease process affecting the area.

A vet collects the fluid using a sterile protocol, to avoid contamination of the cavity itself. The sample is sometimes centrifuged to concentrate the cells, and then they are spread on a slide and stained. The slide is then analyzed by a veterinarian or pathologist.

An example of this diagnostic that is helpful is the collection and analysis of abdominal fluid. In the roomy abdomen of a horse, there is normally only about 50-100ml (appx. 2-3 oz) of free fluid. The cell count is normally low - only about 4000 cells per unit, and the cells are of a particular type. If the abdomen is infected, the cell count can increase to 200,000 or more cells per unit, and the predominant cell type changes too.

Why A Vet Chooses This Diagnostic


Diagnoses Your Vet May Consider

This test could rule out or confirm any of the following diagnoses.

Very Common
Less Common
more diagnoses
Cell types and counts provide helpful information to better understand a disease process within a body cavity.


Sometimes uncontaminated samples (without blood) can be difficult to obtain.

Prior needle puncture of cavities can cause a change in the cell count and cell types.

your role

Questions To Ask Your Vet:
  • Can you trust the results of the cell count or might there be another explanation (contamination) for your findings?

Author: Doug Thal DVM Dipl. ABVP