A comparison of alfaxalone and propofol on intraocular pressure in healthy dogs.

OBJECTIVE: To compare the effects of alfaxalone and propofol on intraocular (IOP) pressure in the canine eye. ANIMALS STUDIED: Twenty-three healthy adult dogs. PROCEDURES: Dogs were randomized to receive intravenous propofol (n = 11) or alfaxalone (n = 12) until loss of jaw tone, 20 min after intravenous premedication (acepromazine 0.02-0.03 mg/kg and hydromorphone 0.05-0.1 mg/kg). IOP was measured at baseline (BL), 20 min postpremedication (postpremed), loss of jaw tone (postinduct), and immediately following orotracheal intubation (postintub). Between- and within-treatment effects were analyzed with two-way and one-way repeated measures ANOVA with Bonferroni's post hoc test, respectively. P < 0.05 was considered significant. RESULTS: No significant IOP differences were detected between alfaxalone or propofol groups at any time point (P > 0.05). Propofol: IOP did not change between BL (15.5 ± 2.7 mmHg) and postpremed (16.2 ± 3.6 mmHg, P > 0.05), or postinduct (19.1 ± 5.2 mmHg) and postintub (21.0 ± 4.6 mmHg, P > 0.05), but differed significantly between BL and postinduct (P < 0.0001), and postintub (P < 0.0001). Alfaxalone: IOP did not change between BL (15.7 ± 2.8 mmHg) and postpremed (15.3 ± 4.1 mmHg, P > 0.05), or postinduct (19.2 ± 4.9 mmHg) and postintub (20.5 ± 4.5 mmHg, P > 0.05), but differed significantly between BL and postinduct (P < 0.01), and postintub (P < 0.0001). CONCLUSIONS: These data show a potentially clinically significant increase in IOP following induction with propofol or alfaxalone, but no difference between agents.

Development of reference intervals for pupillometry in healthy dogs.

Background: Pupillometry, the measurement of pupil size and reactivity to a stimulus, has various uses in both human and veterinary medicine. These reflect autonomic tone, with the potential to assess nociception and emotion. Infrared pupillometry reduces inaccuracies that may occur when the pupillary light reflex is determined subjectively by the examiner. To our knowledge, there are no published studies outlining normal reference intervals for automated pupillometry in dogs. Objective: The objective of this study was to develop de novo automated pupillometry reference intervals from 126 healthy canine eyes. Methods: The pupillary light reflex (PLR) was measured with a handheld pupillometer (NeurOptics™ PLR-200™ Pupillometer). Parameters recorded included maximum pupil diameter (MAX), minimum pupil diameter (MIN), percent constriction (CON), latency (LAT), average constriction velocity (ACV), maximum constriction velocity (MCV), average dilation velocity (ADV) and time to 75% pupil diameter recovery (T75). One measurement was obtained for each eye. Results: The following reference intervals were developed: MAX (6.05-11.30 mm), MIN (3.76-9.44 mm), CON (-37.89 to -9.64 %), LAT (0.11-0.30 s), ACV (-6.39 to -2.63 mm/ s), MCV (-8.45 to -3.75 mm/s), ADV (-0.21-1.77 mm/s), and T75 (0.49-3.20 s). Clinical significance: The reference intervals developed in this study are an essential first step to facilitate future research exploring pupillometry as a pain assessment method in dogs.

Refractive states of eyes and associations between ametropia and age, breed, and axial globe length in domestic cats.

OBJECTIVE: To determine the refractive states of eyes in domestic cats and to evaluate correlations between refractive error and age, breed, and axial globe measurements. ANIMALS: 98 healthy ophthalmologically normal domestic cats. PROCEDURES: The refractive state of 196 eyes (2 eyes/cat) was determined by use of streak retinoscopy. Cats were considered ametropic when the mean refractive state was ≥ ± 0.5 diopter (D). Amplitude-mode ultrasonography was used to determine axial globe length, anterior chamber length, and vitreous chamber depth. RESULTS: Mean ± SD refractive state of all eyes was -0.78 ± 1.37 D. Mean refractive error of cats changed significantly as a function of age. Mean refractive state of kittens (≤ 4 months old) was -2.45 ± 1.57 D, and mean refractive state of adult cats (> 1 year old) was -0.39 ± 0.85 D. Mean axial globe length, anterior chamber length, and vitreous chamber depth were 19.75 ± 1.59 mm, 4.66 ± 0.86 mm, and 7.92 ± 0.86 mm, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Correlations were detected between age and breed and between age and refractive states of feline eyes. Mean refractive error changed significantly as a function of age, and kittens had greater negative refractive error than did adult cats. Domestic shorthair cats were significantly more likely to be myopic than were domestic mediumhair or domestic longhair cats. Domestic cats should be included in the animals in which myopia can be detected at a young age, with a likelihood of progression to emmetropia as cats mature.