Dose-Response Evaluation of Sugammadex for Reversal of Deep Rocuronium-Induced Neuromuscular Block in Cats

Background: Sugammadex is a selective γ-cyclodextrin compound that encapsulates steroidal neuromuscular blocking agents such as rocuronium, allowing rapid and predictable recovery from neuromuscular block (NMB). However, dose-response information in feline patients remains limited. Methods: In this prospective, randomized, and blinded experimental study, three intravenous doses of sugammadex (2, 4, and 8 mg kg^-1) were compared for the reversal of profound rocuronium-induced NMB (0.6 mg kg^-1) in thirty adult ASA I cats anesthetized with sevoflurane. Neuromuscular function was continuously assessed using acceleromyography (train-of-four stimulation). The onset and recovery times for T₁/T₀ ratios of 25-90%, T₄/T₁ ratios, and recovery index were measured, along with cardiovascular and respiratory parameters. Results: Sugammadex shortened the recovery time in a dose-dependent manner. The mean time to achieve T₁/T₀ = 90% was 519 s (2 mg kg^-1), 300 s (4 mg kg^-1), or 256.8 s (8 mg kg^-1). The 43-s difference between the two higher doses was not statistically significant (p = 0.317) and, therefore, not clinically relevant. Greater interindividual variability in the reversal time was observed at a dose of 4 mg kg^-1. One cat in this group experienced transient recurarization, and no adverse cardiovascular effects were detected. Conclusions: Both 4 and 8 mg kg^-1 of sugammadex produced rapid and complete reversal of profound rocuronium-induced NMB in sevoflurane-anesthetized cats without hemodynamic compromise. These results apply to healthy ASA I cats, and further studies are warranted in animals with systemic disease.