THC-Related QT Prolongation in Dogs Needed Heart-Rate Correction for Interpretation
Longer uncorrected QT intervals in the canine cannabis study did not by themselves establish equivalent prolongation after accounting for heart rate. The paper evaluated corrected intervals as a separate measure.
The study measured several cardiac intervals
Six male Beagles received THC, CBD and combination oils in a crossover design. THC prolonged uncorrected QT intervals at selected cumulative doses. The investigators also calculated a heart-rate-corrected QT using Van de Water’s formula rather than treating the uncorrected interval as the only cardiac endpoint.
Correction addresses a different interpretive question
QT duration varies with cardiac timing, so a change alongside altered RR intervals requires context. The authors discussed corrected QT values remaining within their referenced normal range. That observation is narrower than saying THC produced no cardiac effects, because other interval changes were present.
A biomarker is not an observed clinical event
Neither an altered interval nor a corrected value within a reference range establishes the incidence of dangerous arrhythmias. Six healthy male dogs under acute monitored conditions cannot characterize rare events or every clinical population. The separate T-wave measures also did not show significant changes in the tested comparisons. These findings concern veterinary physiology and do not supply a human THC blood threshold. The useful distinction is to report the raw interval, the correction method and the clinical observations separately before drawing a cardiac-risk conclusion.
Related analysis: the canine study’s separate physiological outcomes.
Research cited
Rutjanavate, Dong and Sawangkoon. Cumulative Effects of Cannabis Oils on Body Temperature, Electrocardiography, Heart Rate Variability, Blood Pressure, and Respiratory Function in Telemetered Dogs. DOI: 10.4103/IJVSM.IJVSM_3_25.
