Effects of dexmedetomidine alone or in combination with opioids on intraocular pressure in healthy Beagle dogs

ObjectiveTo evaluate the effects of dexmedetomidine alone or in combination with different opioids on intraocular pressure (IOP) in dogs.Study designExperimental, prospective, crossover, randomized, blinded study.AnimalsA total of six Beagle dogs (two males and four females) aged 2 years and weighing 15.9 ± 2.9 kg (mean ± standard deviation).MethodsDogs were distributed randomly into seven treatments (n = 6 per treatment) and were administered dexmedetomidine alone (10 μg kg^–1; Dex) or in combination with butorphanol (0.15 mg kg^–1; DexBut), meperidine (5 mg kg^–1; DexMep), methadone (0.5 mg kg^–1; DexMet), morphine (0.5 mg kg^–1; DexMor), nalbuphine (0.5 mg kg^–1; DexNal) or tramadol (5 mg kg^–1; DexTra). All drugs were administered intramuscularly. IOP was measured before drug injection (time 0, baseline) and every 15 minutes thereafter for 120 minutes (T15–T120).ResultsThere were significant reductions in IOP compared with baseline in treatments Dex and DexMep at times T30–T120, and in treatment DexMet at T15–T90. IOP decreased compared with baseline in treatments DexBut, DexNal and DexTra at all evaluation times. No changes in IOP were seen in treatment DexMor. The mean IOP values in treatment DexMet at T105–T120 were higher than those for other treatments.Conclusions and clinical relevanceDexmedetomidine alone or in combination with butorphanol, meperidine, methadone, nalbuphine or tramadol resulted in decreased IOP for 120 minutes in dogs. The magnitude of the reduction was small and lacked clinical significance.