Effect of anesthetic induction with propofol, alfaxalone or ketamine on intraocular pressure in cats: a randomized masked clinical investigation

Objective: To compare the effect of propofol, alfaxalone and ketamine on intraocular pressure (IOP) in cats. Study design: Prospective, masked, randomized clinical trial. Animals: A total of 43 ophthalmologically normal cats scheduled to undergo general anesthesia for various procedures. Methods: Following baseline IOP measurements using applanation tonometry, anesthesia was induced with propofol (n = 15), alfaxalone (n = 14) or ketamine (n = 14) administered intravenously to effect. Then, midazolam (0.3 mg kg⁻¹) was administered intravenously and endotracheal intubation was performed without application of topical anesthesia. The IOP was measured following each intervention. Data was analyzed using one-way ANOVA and repeated-measures mixed design with post hoc analysis. A p-value <0.05 was considered significant. Results: Mean ± standard error IOP at baseline was not different among groups (propofol, 18 ± 0.6; alfaxalone, 18 ± 0.7; ketamine, 17 ± 0.5 mmHg). Following induction of anesthesia, IOP increased significantly compared with baseline in the propofol (20 ± 0.7 mmHg), but not in the alfaxalone (19 ± 0.8 mmHg) or ketamine (16 ± 0.7 mmHg) groups. Midazolam administration resulted in significant decrease from the previous measurement in the alfaxalone group (16 ± 0.7 mmHg), but not in the propofol group (19 ± 0.7 mmHg) or the ketamine (16 ± 0.8 mmHg) group. A further decrease was measured after intubation in the alfaxalone group (15 ± 0.9 mmHg). Conclusions and clinical relevance: Propofol should be used with caution in cats predisposed to perforation or glaucoma, as any increase in IOP should be avoided.