Cumulative Effects of Cannabis Oils on Body Temperature, Electrocardiography, Heart Rate Variability, Blood Pressure, and Respiratory Function in Telemetered Dogs.

Background: Cannabis oils are progressively being investigated as potential treatments for various health conditions in dogs. However, their safety profiles in this species remain poorly understood. Objectives: This study evaluated the effects of incremental doses of cannabis oils containing tetrahydrocannabinol (THC), cannabidiol (CBD), and their combination (THC + CBD) on cardiovascular and respiratory parameters in dogs. Materials and Methods: Six male Beagles participated in a 3 × 3 crossover study. Acute cumulative doses (1, 2, 4, 8, and 16 mg/kg) were administered via the oromucosal route at 2-h intervals. Measurements included rectal temperature, electrocardiography, heart rate variability, blood pressure, and respiratory plethysmography. Results: All dogs tolerated the treatments, although adverse clinical signs were observed with THC and THC + CBD, including shivering and vomiting, with THC alone additionally causing ataxia and urinary incontinence. Both THC and THC + CBD caused significant hypothermia starting at a dose of 2 mg/kg, and they also shortened PQ intervals at doses of 4, 8, and 16 mg/kg. THC also significantly prolonged RR and QT intervals at doses of 2, 4, and 8 mg/kg, but not THC + CBD. CBD tended to increase standard deviation of normal RR intervals, root mean square of successive differences, and total power at doses of 8 and 16 mg/kg, while THC and THC + CBD had no significant effect on these parameters. These oils did not produce significant effects on blood pressure or respiratory function within these dose ranges. Conclusions: CBD oil was well-tolerated, whereas THC and THC + CBD oils induced significant side effects starting at 2 mg/kg. This study establishes a basis for determining appropriate cannabis oil dosages for future clinical studies in dogs.