title: Non-invasively assessing disturbance and stress in laboratory rats by scoring chromodacryorrhoea.
abstract: In rats, like many rodents, Harderian glands next to the orbits secrete porphyrins, lipids and other compounds. High levels of secretion lead to chromodacryorrhoea (red or "bloody" tears), often taken as a sign of stress or disease. Here, we developed a scoring system for recording chromodacryorrhoea in a quantitative way, and investigated whether the low-level, transient Harderian secretions of normal, healthy rats correlate with low to moderate levels of stress or disturbance. Rather than exposing our subjects (24 Lister Hoodeds, housed in 11 single-sex cages) experimentally to stressors, we made opportunistic use of three likely sources of low-level stress within the unit: 1) building maintenance work, taking several hours and involving several potential stressors; 2) visits by unfamiliar humans, and the other mild sources of disturbance normal in an animal unit; and 3) social status within the cage. The mean daily chromodacryorrhoea score increased most with the severe disturbance of building maintenance work (F1,9 = 602.67, p < < 0.0001), and also increased--though to a lesser extent--with the mild disturbance of visitors and similar (F1,9 = 8.77, p = 0.008), while being the subordinate member of a cage-group had a smaller effect still (F1,6 = 7.86, p = 0.03). Individual rats scored consistently across treatment conditions, and there was also significant inter-observer reliability between independent scorers. We therefore suggest that scoring chromodacryorrhoea could be a simple, practical and non-invasive way of sensitively assessing the impact on rats of housing, husbandry, or procedures.
authors.affiliation: Department of Zoology, Oxford University, South Parks Road, Oxford OX1 3PS, UK. georgia.mason@zoology.oxford.ac.uk
authors.forename: Georgia
authors.initials: G
authors.lastname: Mason
authors.forename: David
authors.initials: D
authors.lastname: Wilson
authors.forename: Charlotte
authors.initials: C
authors.lastname: Hampton
authors.forename: Hanno
authors.initials: H
authors.lastname: Würbel
mesh_terms: D000818:Animals; D000830:Animals, Laboratory; D005260:Female; D006243:Harderian Gland / Q000378:metabolism*; D008297:Male; D051381:Rats; D013312:Stress, Physiological