Alfaxalone versus propofol in dogs: A randomised trial to assess effects on peri-induction tear production, intraocular pressure and globe position

The purpose of this randomised trial was to compare the effects of alfaxalone and propofol on tear production (STT-1), intraocular pressure (IOP) and globe position (GP) in healthy dogs. Fourteen Beagles were randomly divided into two groups; dogs in one group received alfaxalone (3 mg/kg) (n=7) and dogs in the other group received propofol (6 mg/kg) (n=7), both administered intravenously. IOP and GP were evaluated at basal time (Tb) and T2,5,10,15,20,25&30 (minutes after complete drug administration). STT-1 was evaluated at Tb and T10,20&30. STT-1 and IOP results were analysed using analysis of variance and GP was analysed using the likelihood ratio χ2 test. Dogs in the alfaxalone group showed a significant reduction in STT-1 at T10&20 (P<0.05), while the propofol group did not show statistically significant differences in this parameter over time. Both anaesthetic drugs produced a transient elevation of IOP at T2 (P>0.05), which then decreased (P<0.01). While alfaxalone caused a ventral globe deviation that lasted from T2 to T10 (P<0.05) and was fully recovered at T30, propofol induced a ventral globe deviation from T2 to T5 (P<0.05), being restored at T20. These results suggest that both alfaxalone and propofol can be safely used for intraocular surgery, as they significantly reduce IOP. Furthermore, anaesthetic induction with propofol would be especially recommended for dogs with tear deficiencies.