Effective mydriasis in juvenile loggerhead turtles (Caretta caretta) following topical administration of rocuronium bromide and 10% phenylephrine

Mydriasis in eastern box turtles (Terrapene carolina carolina) following topical administration of proparacaine, 10% phenylephrine, and rocuronium bromide

OBJECTIVE

To determine the mydriatic effect of topical 10% phenylephrine with 10 mg/mL rocuronium bromide and compare this protocol with and without pretreatment with proparacaine.

ANIMALS STUDIED

Ten client-owned pet adult eastern box turtles (Terrapene carolina carolina).

PROCEDURES

All turtles were sedated with 8 mg/kg alfaxalone intramuscularly. One group of four turtles received four 20 μL drops of 10% phenylephrine and four 20 μL drops of rocuronium bromide in the right eye. Another group of four turtles received one standard drop of proparacaine followed by four 20 μL drops of 10% phenylephrine and four 20 μL drops of rocuronium bromide in the right eye. Two control group turtles received four 20 μL drops of saline in the right eye. The left eye was untreated in all turtles. Drops of the same type were separated by 2 min while drops of different types were separated by 5 min. Pupil size was recorded at 0, 15, 30, 60, 90, 120, 180, 240, and 360 min after administration of the final drop.

RESULTS

Treatment with 10% phenylephrine and rocuronium bromide resulted in pupil diameter changes from baseline that were statistically significant from zero at 60, 90, and 120 min in the non-proparacaine group and 90 min in the proparacaine group. The time to peak effect was 90 min in the proparacaine group and 75 min in the non-proparacaine group. Saline-treated pupils in the control group decreased in diameter over the study period. Overall, the treated eyes of the proparacaine group and non-proparacaine group were not different from each other, but both dilated more than the control group.

CONCLUSIONS

Rocuronium bromide and 10% phenylephrine can produce effective and safe mydriasis in eastern box turtles, but there was wide interindividual variation in effectiveness. Proparacaine did not improve the mydriatic effect.

Ophthalmic findings and parameters in Western tiger salamanders (Ambystoma mavortium) from northern Colorado

OBJECTIVE

The aim of this study was to document ophthalmic examination findings and provide reference values for ocular examinations and diagnostics in clinically normal Western tiger salamanders (Ambystoma mavortium) and to evaluate the mydriatic effect of a topical rocuronium bromide and identify any adverse effects.

ANIMALS STUDIED

Sixteen Western tiger salamanders.

PROCEDURE

A complete ophthalmic examination, including intraocular pressure via rebound tonometry [iCare® TonoVet (dog-setting) or iCare® TonoVet Plus (dog-setting)], and fluorescein and Rose Bengal stains, was performed. Ocular surface flora culture swabs were collected for microbiology in four salamanders. Rocuronium bromide (50 μL; 0.01 mg) was administered into each eye in three salamanders. Pupil size and constriction ability were evaluated up to 60 min following administration of rocuronium bromide. Distant visual examination and Doppler heart rate were used to monitor for potential adverse effects of rocuronium bromide.

RESULTS

Observed ocular abnormalities included lipid keratopathy/keratitis (19%; 3/16), parasitic ophthalmitis (19%; 3/16), and cataracts (6.3%; 1/16). A significant difference was found between tonometry with iCare® TonoVet (11.5 ± 2.7 mmHg) versus TonoVet Plus (15.4 ± 3.7 mmHg) (p = .025). Fluorescein and Rose Bengal stains were negative in all salamanders. Ocular surface microbiology revealed a high incidence of contamination from environmental flora, with the most common isolate being unidentified as Gram-negative nonfermenters (75%; 3/4). No significant change in pupil size or constriction ability was observed with rocuronium bromide.

CONCLUSION

This is the first study to document ocular examination findings and diagnostics in captive and wild urodeles and may serve as a reference for clinical assessment and future studies of the Western tiger salamander.

ASSESSMENT OF OPHTHALMIC DIAGNOSTIC PARAMETERS, CONJUNCTIVAL FLORA, AND PHARMACOLOGIC DILATION OF A LARGE POPULATION OF JUVENILE AMERICAN ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS)

American alligators (Alligator mississippiensis) are an important apex predator of semiaquatic habitats of the southern United States. Commercial alligator farming has grown in the last several decades, leading to a need to understand the health conditions that affect this species to ensure appropriate management and welfare. The aims of this study were 1) to establish and describe normative data including results of common ophthalmic diagnostic tests and conjunctival flora, 2) document ocular pathology in this population, and 3) assess the effect of topical rocuronium bromide and 10% phenylephrine for facilitating pharmacologic mydriasis. A total of 165 juvenile American alligators were evaluated in this study. Assessment included palpebral fissure length (PFL), intraocular pressure (IOP), strip meniscometry (SM), central corneal thickness (CCT), anterior segment examination, and bacterial and fungal culture sampling of the conjunctiva. Topical rocuronium bromide (RB) and 10% phenylephrine (PE) were applied to the right eye (OD) of eight individuals, and pupil diameter (PD) of both eyes measured at regular time intervals. Mean (±standard deviation [SD]) PFL was 10.55 ± 1.47 mm, IOP was 8.16 ± 1.48 mmHg, CCT was 150.06 ± 8.25 µm, and SM was 3.42 ± 2.07 mm/5 s. Culture results stress the importance of proper handling protocols in crocodilians given the high number of opportunistic pathogens isolated from the conjunctiva, as well as the first report of isolation of Lactococcus garvieae in this species. Acquired ophthalmic lesions, likely traumatic, were recorded and no congenital anomalies were observed. Topical administration of RB and PE resulted in a significant increase in nonilluminated pupil diameter (PD) starting at 20 min, and maximum dilation was achieved at 90 min. Fundic examination was achievable, and no adverse systemic effects were noted. This study contributes to a growing body of knowledge regarding ocular health of American alligators.

Electroretinography, Ocular Ultrasonography, and Phacoemulsification of Bilateral Cataracts in Two Juvenile Loggerhead Sea Turtles (Caretta caretta) of the Mediterranean Region

Bilateral cataracts were diagnosed in two rescued juvenile, immature loggerhead sea turtles (Caretta caretta), weighing 1.65 and 1.7 kg. Both animals showed vision impairment and difficulty in feeding without assistance. In fact, they did not notice the presence of the food in the tank unless it was brought close to touching the mouth. Ocular ultrasonography and electroretinography showed no lesions of the vitreal body and retinal layer, therefore, both animals were candidates for bilateral cataract surgery. Topical administration of tropicamide + phenylephrine alternating with rocuronium resulted in only minimal mydriasis. Administration of intracameral rocuronium did not improve mydriasis. Phacoemulsification using a one-handed technique was performed bilaterally with a phacoemulsification device (Sovereign, AMO (Abbott Medical Optics^®). After surgery, the systemic anti-inflammatory drug (dexamethasone 0.2 mg/kg, IM daily for one week) and antibiotics (enrofloxacin 10 mg/kg IM q 72 h, for 4 weeks; ceftazidime 20 mg/kg IM q 72 h for 3 weeks) were administered. Topical ofloxacin, flurbiprofen and tobramycin/dexamethasone were instilled TID for 4 weeks. Both turtles regained vision in both eyes. Results at a 10-month follow-up were satisfactory. This is the first report of cataracts in turtles rescued in the Mediterranean Sea and the first description of surgical treatment of cataracts in loggerhead turtles so young.

Neurological examination in healthy adult inland bearded dragons (Pogona vitticeps)

OBJECTIVE

To evaluate neurological tests and expected results in inland bearded dragons (Pogona vitticeps) and generate recommendations for bearded dragon-specific neurological examination.

ANIMALS

26 healthy adult inland bearded dragons.

PROCEDURES

A complete neurological examination utilizing tests described in both mammals and reptiles was performed on each lizard, and test feasibility and outcome were recorded.

RESULTS

Tests with poor feasibility included oculocardiac reflex (successfully completed in 62% [16/26] of animals) and voluntary ambulation and swallowing by use of a food item (0% [0/26] of animals). Tests with outcomes considered abnormal in mammals but attributable to normal bearded dragon behavior included head position (head tilt present in 12% [3/26]) and head movement (head bob present in 4% [1/26]). Many tests had absent or inconsistent outcomes, including menace response (present in 19% [5/26]), proprioceptive positioning (present in 4% [1/26] in the thoracic limbs and 0% [0/26] in the pelvic limbs), vent reflex (present in 27% [7/26]), and myotatic reflexes (biceps present in 8% [2/26]; patellar, gastrocnemius, and triceps present in 0% [0/26]). Extensor postural thrust was absent in all successfully tested animals, but a novel reflex termed the caudal thoracic extensor reflex was noted instead in all observed animals (100% [21/21]).

CLINICAL RELEVANCE

Tests with poor feasibility or inconsistent outcomes should have low priority or be excluded from neurological examinations of inland bearded dragons. Normal behaviors should be considered for head position and movement. A bearded dragon-specific neurological examination protocol derived from these findings is described and recommended in order to decrease stress and improve neurolocalization.

COMPARISON OF INTRAOCULAR PRESSURE MEASUREMENT USING REBOUND AND APPLANATION TONOMETRY IN LOGGERHEAD (CARETTA CARETTA) SEA TURTLES

This study aimed to evaluate intraocular pressure (IOP) estimates in healthy eyes of Caretta caretta using rebound tonometry in comparison with applanation tonometry. Twenty-three healthy C. caretta (housed at the Marine Turtle Research Center) without preexisting ophthalmic disease were enrolled in the study. IOP measurements were obtained by the same ophthalmologist, with the turtle in ventral recumbency between 2:30 p.m. and 4:30 p.m., using a rebound tonometer (RT; TonoVet) in dog calibration mode, and after topical anesthesia, an applanation tonometer (AT; Tono-Pen) in both eyes. The average of three readings per instrument was used for analysis. The agreement between the two tonometers was assessed by Bland-Altman analysis and intraclass correlation coefficient (ICC). Moreover, differences in IOP between the two tonometers were analyzed using the Mann-Whitney test. Moderate agreement was found between the two tonometers (ICC, 0.663; 95% confidence interval, 0.206-0.857). The median, Q1, and Q3 IOP obtained with AT (6.2, 4.7, and 9.1 mm Hg) were significantly lower (P = 0.001) than that obtained with RT (9.7, 8.3, and 11.6 mm Hg). It was not possible to obtain an instrument automatically generated mean of four values with AT because of retraction of the globe by the animals, and IOP measurement was unsuccessful in 7 eyes. In conclusion, IOP readings from the RT were statistically higher than those from the AT. RT proved to be more feasible because of the light, short-lasting contact with the cornea.

Safety and efficacy of unilateral topical application of rocuronium bromide in healthy scops owls (Otus scops)

OBJECTIVE

To evaluate the safety and efficacy of unilateral topical application of rocuronium bromide in scops owls.

ANIMALS STUDIED

Ten healthy adult scops owls.

PROCEDURES

Birds weighting between 82-111 g were enrolled. Complete physical and ophthalmic examinations were performed. Each animal received a single dose of 0.15 mg of rocuronium bromide (30 µL) in a randomly selected eye. Static pupillometric evaluations were performed before and after drug instillation at 0, 30, 60, 90, and 120 minutes, in a room with fixed light intensity. Physical and ophthalmic examinations were carried out to evaluate possible adverse effects.

RESULTS

Median pupil (95% CI) size at t₀ was 7.10 mm (5.51-7.41) for placebo eyes and 7.22 mm (6.93-7.48) for treated eyes, showing no statistical differences (P > .05). When compared to the placebo eye, significant mydriasis was achieved at t₃₀ [8.18 mm (7.22-9.00)] (P = .014) and lasting until t₉₀ [7.35 mm (6.20-9.52)] (P = .004). Maximal mydriasis was obtained at t₆₀ [8.63 mm (7.72-9.81)] (P = .001). During this period, the treated eye no longer responded to direct light stimulation. Complete mydriasis was observed in 5/10 birds (mean weight 97.4 g). Pupil size at t₉₀ and t₁₂₀ did not differ from baseline (P > .05) in treated eyes. No adverse effects were seen during the study period.

CONCLUSION

Single-dose topical rocuronium bromide (0.15 mg) is a safe and effective medium duration mydriatic agent in scops owls. Further studies are needed to evaluate bilateral topical application and standardize the mydriatic protocol.