Use of phenol red thread tests to evaluate tear production in clinically normal Amazon parrots and comparison with Schirmer tear test findings.
OBJECTIVE
To determine phenol red thread test (PRTT) values in eyes of clinically normal Hispaniolan Amazon parrots before and after topical application of an ophthalmic anesthetic agent and compare findings with Schirmer tear test (STT) values.


METHODS
Evaluation study.


METHODS
24 Amazona ventralis parrots from a research colony.


METHODS
On 4 occasions (1-week intervals), all birds underwent a thorough ophthalmic examination of both eyes, which included (in sequence) performance of a PRTT and an STT; topical ocular application of proparacaine hydrochloride; and performance of another PRTT and another STT. Correlations between PRTT and STT values recorded with and without topical anesthesia were assessed.


RESULTS
Without topical anesthesia, mean +/- SD PRTT value was 12.5 +/- 5.0 mm/15 s (range, 1 to 25 mm/15 s). With topical anesthesia, the PRTT value was 12.6 +/- 5.4 mm/15 s (range, 2 to 24 mm/15 s). Without topical anesthesia, mean STT value was 7.9 +/- 2.6 mm/min (range, 0 to 13 mm/min). With topical anesthesia, the STT value was 5.1 +/- 3.3 mm/min (range, 0 to 18 mm/min). The correlation of PRTT and STT values recorded with or without topical anesthesia was weak (r = 0.51 and r = 0.32, respectively).


CONCLUSIONS
Results indicated that the PRTT and STT were both viable methods for measurement of tear production in Hispaniolan Amazon parrots. Topical application of an ophthalmic anesthetic agent did not have a significant effect on the PRTT values but significantly decreased the STT values.
Storey
Eric S
ES
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA. storey@vetmed.lsu.edu
Carboni
Deborah A
DA
Kearney
Michael T
MT
Tully
Thomas N
TN
D046708:Amazona / Q000502:physiology*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D003941:Diagnostic Techniques, Ophthalmological / Q000592:standards / Q000662:veterinary*; D010637:Phenolsulfonphthalein; D013666:Tears / Q000502:physiology*
D000779:Anesthetics, Local; D010637:Phenolsulfonphthalein