Cardiac arrhythmias and electrolyte disturbances in colic horses

Abstract

Background: Despite increased focus on cardiac arrhythmias in horses, the nature and prevalence is still poorly described. Case reports suggest that arrhythmias occurring secondary to systemic disease are seen more commonly in the clinic than arrhythmias caused by cardiac disease. The aim of this study was to investigate the prevalence of arrhythmias in colic horses referred for hospital treatment. Associations between electrolyte disturbances and arrhythmias were also investigated.

Results: Heart rate was 37.4 ± 3.7 bpm in the control group, and 51.6 ± 11.8 bpm, in the colic group, which was significantly different (P < 0.0001). AV blocks and SVPCs were found in both groups, however only colic horses showed VPCs. No significant difference between the two groups was found for AV blocks, SVPCs, and VPCs (P = 0.08 - 0.76). The mean levels of potassium, sodium, ionized calcium, and chloride were significantly lower in the colic group compared to the control group at admission. Mean levels of glucose and L-lactate were significantly elevated in the colic group (P < 0.05).

Conclusions: This study describes prevalence of cardiac arrhythmias and electrolytes concentrations in colic horses compared to healthy controls. Although we only observed VPCs in the colic horses, no significant differences between colic horses and controls were found. Despite the colic horses having electrolyte changes at admission no correlation was found between the electrolyte disturbances and cardiac arrhythmias. Although no clear conclusions can be drawn from the present study, the results indicate that relatively mild colic per se is not pro-arrhythmogenic, whereas severe colic probably are more likely to result in ventricular arrhythmia.

Figure 1

Heart rate and distribution of arrhythmias in controls and colic horses. Arrhythmias/hour, mean ± SD. Significant differences are indicated by asterisks (*** = P < 0.001).

Figure 2

Distribution of blood parameters. Mean ± SD for both groups at T = 0 and T = 24. Significant differences are indicated by asterisks (* = P < 0.05, ** = P < 0.01, *** = P < 0.001). The asterisks placed above the vertical bars indicate significant difference between the two groups. The asterisk placed nearby the horizontal bars indicate significant difference between T = 0 and T = 24 within the group (either control or colic).