The phenol red thread tear test in large Psittaciformes.
OBJECTIVE
To develop a standard method for measuring tear production in large Psittaciformes using the phenol red thread (PRT) tear test. To establish mean PRT tear test values in clinically normal pet birds and to assess the reproducibility of the test.


METHODS
Two geographically distinct populations of healthy, large Psittaciformes (pilot study and study population). Species groups include: cockatoo (17), macaw (22), Amazon (10), African gray (1), eclectus (1) and pionus (1).


METHODS
The PRT was placed under the upper eyelid and both eyelids were held closed throughout the test. The PRT tear test was repeated after 2 months in the pilot study and after approximately 5 min in the study population.


RESULTS
The mean PRT tear test values for the pilot study were OD=28.2 mm/15 s (+/- 6.3 mm), OS=24.1 mm/15 s (+/- 6.6 mm) and OD=25.4 mm/15 s (+/- 3.3 mm), OS=25.5 mm/15 s (+/- 5.2 mm), for the first and second visits respectively. The mean PRT tear test value for the study population was: OD=19.8 mm/15 s (+/- 4.3 mm), OS=20.1 (+/- 3.9 mm) and OD=20.0 mm/15 s (+/- 4.5 mm), OS=19.1 mm/15 s (+/- 3.3 mm), for the first and second tests respectively. There was poor repeatability between tests.


CONCLUSIONS
Results suggest that the PRT tear test is a practical method for measuring tear production in large Psittaciformes, although adaptations to the established diagnostic method are necessary to overcome some anatomical differences present in birds. Good reproducibility of the PRT tear test could not be demonstrated in a clinically normal population of birds but geographic location appears to significantly influence results.
Department of Clinical Studies, School of Medicine, Matthew J Ryan, Veterinary Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA. eholt@rvc.ac.uk
Elaine
E
Holt
Karen
K
Rosenthal
Frances S
FS
Shofer
D000818:Animals; D001715:Bird Diseases / Q000175:diagnosis; D004396:Coloring Agents; D003941:Diagnostic Techniques, Ophthalmological / Q000662:veterinary*; D005128:Eye Diseases / Q000175:diagnosis / Q000662:veterinary; D007202:Indicators and Reagents; D010637:Phenolsulfonphthalein; D010865:Pilot Projects; D011563:Psittaciformes; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013666:Tears / Q000378:metabolism*
D004396:Coloring Agents; D007202:Indicators and Reagents; D010637:Phenolsulfonphthalein