The effects of hypohydration on central venous pressure and splenic volume in adult horses.

BACKGROUND

Central venous pressure (CVP) is used in many species to monitor right-sided intravascular volume status, especially in critical care medicine.

HYPOTHESIS

That hypohydration in adult horses is associated with a proportional reduction in CVP.

ANIMALS

Ten healthy adult horses from the university teaching herd.

METHODS

In this experimental study, horses underwent central venous catheter placement and CVP readings were obtained by water manometry. The horses were then deprived of water and administered furosemide (1 mg/kg IV q6h) for up to 36 hours. Weight, CVP, vital signs, PCV, total protein (TP), and serum lactate were monitored at baseline and every 6 hours until a target of 5% decrease in body weight loss was achieved. The spleen volume was estimated sonographically at baseline and peak volume depletion. Linear regression analysis was used to assess the association of CVP and other clinical parameters with degree of body weight loss over time.

RESULTS

There was a significant association between CVP and decline in body weight (P < .001), with a decrease in CVP of 2.2 cmH(2)O for every percentage point decrease in body weight. Other significant associations between volume depletion and parameters measured included increased TP (P = .007), increased serum lactate concentration (P = .048), and decreased splenic volume (P = .046). There was no significant association between CVP and vital signs or PCV.

CONCLUSIONS AND CLINICAL IMPORTANCE

These findings suggest that CVP monitoring might be a useful addition to the clinical evaluation of hydration status in adult horses.