Retrospective Evaluation of Synchronous Diaphragmatic Flutter in Horses: 37 Cases (2004-2022).

Abstract

OBJECTIVE: To describe the clinical presentation of horses with synchronous diaphragmatic flutter (SDF) and identify clinical and laboratory variables associated with survival. DESIGN: Retrospective study from January 2004 to September 2022. SETTING: Five large animal referral hospitals in the United States. ANIMALS: Thirty-seven horses of various breeds and ages presenting with clinical signs of SDF, excluding animals participating in an endurance competition. All horses were >1&#xa0;year of age. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Variables recorded and analyzed included signalment, clinical and laboratory data, treatments, and outcome. SDF was seen with gastrointestinal disease in 35% (13/37) of horses. The survival for horses with SDF was 78.4% (29/37). Nonsurvivors had a higher heart rate (78&#xa0;&#xb1;&#xa0;15/min) than survivors (58&#xa0;&#xb1;&#xa0;17/min; p&#xa0;=&#xa0;0.01). Nonsurviving horses were more likely than surviving horses to have had nasogastric reflux (odds ratio: 16.8; 95% confidence interval: 1.9-222.8). Compared with survivors, nonsurvivors had a lower sodium concentration (131&#xa0;&#xb1;&#xa0;7&#xa0;mmol/L [131&#xa0;&#xb1;&#xa0;7&#xa0;mEq/L]) and bicarbonate concentration (22.7&#xa0;&#xb1;&#xa0;2.8&#xa0;mmol/L [22.7&#xa0;&#xb1;&#xa0;2.8&#xa0;mEq/L]). Nonsurvivors had higher lactate concentration (7.1&#xa0;&#xb1;&#xa0;3.9&#xa0;mmol/L [64&#xa0;&#xb1;&#xa0;35.1&#xa0;mg/dL]), glucose concentration (20 [13.3-29] mmol/L; 378 [239-522] mg/dL), and gamma-glutamyltransferase activity (51 [27-687] U/L). In horses that had ionized calcium concentration measured, 13 of 18 (72%) had a concentration <1.3&#xa0;mmol/L (5.2&#xa0;mg/dL). CONCLUSIONS: SDF in horses is seen concurrently with gastrointestinal and other diseases, and not all horses present with hypocalcemia. The survival for nonendurance horses with SDF was&#xa0;78%. Nonsurvival was associated with increased heart rate, the presence of nasogastric reflux, and a variety of laboratory abnormalities.