# Impact of Mannitol on Left Atrial Pressure in Dogs With Mitral Regurgitation

## TL;DR

High doses of mannitol can temporarily raise heart pressure in dogs with a heart valve condition, suggesting caution in its use.

## Contribution

The study reveals that high-dose mannitol significantly increases left atrial pressure in dogs with mitral regurgitation.

## Key findings

- Low- and medium-dose mannitol showed minimal impact on mean left atrial pressure (mLAP) in dogs with mitral regurgitation.
- High-dose mannitol caused an immediate and significant increase in mLAP, followed by a return to baseline.
- The findings emphasize the need for cautious dosing of mannitol in dogs with advanced mitral regurgitation.

## Abstract

Mannitol has been proven effective in treating cerebral oedema, owing to its osmotic diuretic effect. However, its potential to transiently increase plasma volume raises uncertainties about its impact on dogs with mitral avalve insufficiency.

This study aimed to investigate the effects of mannitol on haemodynamics and cardiac load in dogs with experimentally induced mitral regurgitation (MR), with a particular focus on the potential adverse effects of high doses of mannitol.

We used implantable telemetry to monitor MR dogs for 12 consecutive hours, recording and comparing the dynamic changes in their mean left atrial pressure (mLAP) and heart rate at different doses of mannitol (low [0.5 g/kg], medium [1 g/kg] and high [2 g/kg]).

Compared with that in the control group, the low‐ and medium‐dose groups demonstrated a proclivity towards increased mLAP after administration, but without statistical significance. The high‐dose group exhibited an immediate increase in the mLAP after administration (p < 0.001), followed by a gradual return to baseline 1 h later.

This study provides crucial reference data for the use of mannitol in treating MR. It is particularly important to exercise caution when administering high doses of mannitol to dogs with advanced stages of MR.

In dogs with stage B mitral regurgitation (MR), low‐ and medium‐dose mannitol had minimal impact on mean left atrial pressure (mLAP) and heart rate (HR). However, high‐dose mannitol significantly increased mLAP, highlighting the importance of cautious dosing to prevent cardiac burden.