OCULAR FINDINGS AND SELECT OPHTHALMIC DIAGNOSTIC TESTS IN CAPTIVE AMERICAN WHITE PELICANS (PELECANUS ERYTHRORHYNCHOS)

Abstract

The aim of this study was to establish normal ophthalmic parameters for select diagnostic tests in American white pelicans (Pelecanuserythrorhynchos). Twenty-one zoo-housed American white pelicans were manually restrained for noninvasive ocular diagnostic testing and complete ophthalmic examination. Tear production quantification using the phenol red thread test (PRTT), fluorescein staining, and intraocular pressure (IOP) evaluation were performed. In addition, conjunctival aerobic bacterial culture and culture-independent 16S rRNA amplicon sequencing were performed on select eyes. Normal variations and ocular abnormalities detected during complete ophthalmic examination were documented and photographed. Direct pupillary light reflex, menace response, and palpebral reflex were present in all birds. The value (mean ± SD) for PRRT and IOP was 14.9 ± 7.84 mm/15 sec and 9.0 ± 1.41 mm Hg oculus uterque, respectively. Conjunctival culture in nine birds revealed no growth for six birds and Staphylococcus aureus growth in three birds. A high relative abundance of Mycoplasma sp. was detected in all samples based on 16S rRNA sequencing. The normal pelican eye was found to have relative conjunctival hyperemia, absent filoplumes, iris color ranging from light blue to brown, and a subcircular vertically elongated pupil. Ophthalmic abnormalities were noted in 10 of 21 birds. Common findings included corneal fibrosis, cataracts, and asteroid hyalosis. The most common ophthalmic abnormality in this species was cataracts.

Tear Production, Intraocular Pressure, Ultrasound Biometric Features and Conjunctival Flora Identification in Clinically Normal Eyes of Two Italian Breeds of Chicken (Gallus gallus domesticus)

“…Given that there is an inter-specific difference in normal tear production in birds, reference values for each species need to be established (Table 5) [8][9][10][18][19][20][21][22][23]25,26,29,[34][35][36][37][38][39][40][41][42][43][44][45][46][47].…”

“…Fornazari et al (2018) examined two populations of two differently aged chickens (5 and 42-day-old chicks), and they also reported that tear production increases with age [29]. American white pelicans (Pelecanus erythrorhynchos) 14.9 ± 7.84 mm/15 s PRTT 6 [44] Atlantic puffins (Fratercula arctica) OD 1 : 7.5 mm/15 s (IQR 13 : 6.5-9.3) OS 2 : 5.0 mm/15 s. (IQR 13 : 4.0-7.…”

“…Many IOP values have been reported using different tonometers in many bird species (Table 6) [1,4,[6][7][8][9][10][11]15,16,[18][19][20][22][23][24][25][26]33,34,38,39,[41][42][43][44][45][46][47]52].…”

“…TP 4 TV-P 5 [16] American white pelicans (Pelecanus erythrorhynchos) 9.0 ± 1.41 TV-P 5 [44] Atlantic puffins (Fratercula arctica) 13 (range 12-15) TV-P 5 [47] Bald eagle (Haliaetus leucocephalus) 21.5 ± 1.7 TP 4 [20] Barn owl (Tyto alba) 1 intraocular pressure; 2 oculus dexter; 3 oculus sinister; 4 Tonopen; 5 TonoVet with no specific species calibration; 6 TonoVet with dog calibration setting; 7 TonoVet with horse calibration setting.…”

Bird Eye Color: A Rainbow of Variation, a Spectrum of Explanations

“…Heterochromia iridis, in which the two irises of a single individual are different colors, has also been reported in several species of birds but seems to be uncommon (Poor 1946, Ryan 2013, David et al 2013, Ruiz-Esparza et al 2017, Kinney et al 2017). However, a study of Common Cuckoos (Cuculus canorus) found a consistent tendency for the left eye to have more extensive dark flecking than the right eye (Yoo et al 2017) -although the mechanism and significance of this tendency is unknown -and few studies have sought to quantify these types of differences.…”