Tail Tattoos for Humane, Safe, and Permanent Identification of Pigmented Mice

H. Yacowitz, A. Yacowitz, R.F. McConnell, G.N. Rao 
AIMS™ Inc, Piscataway, NJ 08854,
McConnell Consulting Pathology Services, FIemington. NJ 08822
National Institute of Environmental Health Sciences. Research Triangle Park, NC 277092 

Identification of albino mice has been accomplished by using tail tattoos with black pigment 242. However, tattoos on pigmented mice were difficult to read. A 2-year study was conducted to evaluate 3 tattoo pigments at two tattoo sites on 320 B6C3Fl mice. Weanling mice were tattooed on the dorsal or ventral skin of the tail by using physiologic saline (controls), black 242, black 242 concentrate B, and blue 270. Mouse weights and tattoo readability scores were recorded monthly. Gross and histologic examination of the tail and proximallymph nodes was conducted when the study ended. There were no differences in weight or mortality. Black 242 concentrate B and blue 270 resulted in easily legible tattoos. Ventral tail tattoos were easier to read e arly in the study, but both dorsal and ventral sites were equally legible after 9 months, as skin color became lighter with age. Microscopic examination of tissues revealed pigments deposited largely in the subepithelial dermis within macrophages. Pigments were essentially inert and caused no adverse effects on tissues or macrophages. Tail tattooing by use of black 242 concentrate B or blue 270 was a safe, permanent, and minimally invasive procedure for identification of pigmented mice. These results extend data obtained in a preliminary study. Supported by NTEHS contracts N43-ES-81001 and N44-ES-92004. 

CONTEMPORARY TOPICS IN LABORATORY ANIMAL SCIENCE 
VOL. 33 NO.4 PG A26, JULY 1994

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