Acute toxicity of marking pen emissions

The Pen Is Milder Than the Blade: Identification Marking Mice Using Ink on the Tail Appears More Humane Than Ear-Punching Even with Local Anaesthetic

Simple Summary

Laboratory mice often look identical, so they are commonly marked by cutting the ear via ear-punching, or marking the tail with permanent marker. Ear-punching is permanent but could be painful, and mice could become stressed by weekly tail-marking, so we compared impacts on mice over 5 weeks. We also explored whether local anaesthetic cream could reduce any ear-punching effects. We found that ear-punching, even with anaesthetic, caused mice to be sniffed and groomed by their cagemates for at least 5 min after marking. Mice ear-punched with anaesthetic also groomed themselves and their ears ~5 times more than tail-marked and control mice. Facial grimacing was most common in the unmarked cagemates of tail-marked mice, and possibly in mice ear-punched with anaesthetic. The next day, mice ear-punched with anaesthetic were significantly less likely to eat unfamiliar food in an anxiety test than tail-marked or control mice. Over 5 weeks, ear-punched mice approached the handler significantly less than unmarked mice did, and tail-marked mice showed reduced defecation during re-marking. Other behaviour, bodyweight, and corticosterone showed no treatment effects. This suggests ear-punching caused some signs of pain and anxiety, and anaesthetic did not help. Tail-marking appeared more humane, showing no differences from the controls.

Abstract

Identification marking mice commonly involves ear-punching with or without anaesthetic, or tail-marking with ink. To identify which is most humane, we marked weanling male BALB/c mice using ear-punching (EP), ear-punching with anaesthetic EMLA^TM cream (EP+A), or permanent marker pen (MP). We compared marked mice, unmarked cagemates, and control mice (n = 12–13/group) for 5 weeks, reapplying MP weekly. Treatment-blind observations following marking showed that EP and EP+A mice were allogroomed (p < 0.001) and sniffed (p < 0.001) by their cagemates more than MP and control mice were. EP+A mice groomed themselves (p < 0.001) and their ears (p < 0.001) ~5 times more than most other mice; their cagemates also increased self-grooming (p < 0.001). Unmarked MP cagemates (p = 0.001), and possibly EP+A mice (p = 0.034; a nonsignificant trend), grimaced the most. The following day, half the EP+A mice showed hyponeophagia versus no MP and control mice (p = 0.001). Over the 5 weeks, EP mice approached the handler significantly less than unmarked cagemates did (p < 0.001). Across weeks, defecation during marking of MP mice decreased (p < 0.001). Treatment showed no effects on immediate responses during marking, aggression, bodyweight, plus-maze behaviour or corticosterone. MP mice showed no differences from controls, whilst EP and EP+A mice showed altered behaviour, so ink-marking may be the more humane identification method.

Marked for life? Effects of early cage-cleaning frequency, delivery batch, and identification tail-marking on rat anxiety profiles

Daily handling of preweanling rats reduces their adult anxiety. Even routine cage-cleaning, involving handling, reduces adult anxiety compared with controls. Cage-cleaning regimes differ between animal breeders, potentially affecting rodent anxiety and experimental results. Here, 92 adult male rats given different cage-cleaning rates as pups, were compared on plus-maze, hyponeophagia, corticosterone, and handling tests. They were pair-housed and half were tail-marked for identification. Anxiety/stress profiles were unaffected by cage-cleaning frequency, suggesting that commercial-typical differences in husbandry contribute little variance to adult rat behavior. However, delivery batch affected some elevated plus-maze measures. Also, tail-marked rats spent three times longer on the plus-maze open arms than their unmarked cagemates, suggesting reduced anxiety, yet paradoxically they showed greater chromodacryorrhoea responses to handling, implying increased aversion to human contact. A follow-up study showed that rats avoided the odor released from the marker pen used. Thus, apparently trivial aspects of procedure can greatly affect experimental results.

Science-based recommendations to prevent or reduce potential exposure to biological, chemical, and physical agents in schools

The U.S. General Accounting Office (GAO) documented generally poor conditions of school facilities in the early 1990s. Previous papers examined, for time intervals ending before 2002, relationships between education facility indoor air and environmental quality (IEQ), including adequate ventilation, and occupant health and productivity. Research on IEQ related specifically to new or refurbished traditional school construction, or portable classrooms, is limited. A review of school IEQ literature through fall 2003 was conducted. Then, acknowledging the limited resources and competing priorities facing American schools, practical science-based, best practices recommendations to promote IEQ and hence prevent or reduce potential occupant exposure to biological, chemical, and physical agents of concern were proposed. Electronic search engines, conference proceedings, the Internet, and reference lists of peer-reviewed papers and reports were used. Eighteen best practices based on scientific references are presented.