An anesthetized raccoon. 



The researchers are also evaluating methods and 

 techniques used to vaccinate free-roaming wildlife 

 against rabies. 



Use of Rhodamine B as a New Biomarker for 

 Raccoons — The Oral Rabies Vaccination (ORV) 

 program, administered by WS, has long desired an 

 effective, easy-to-use biomarker that would allow for 

 noninvasive identification of animals that have been 

 exposed to ORV baits. The ORV program currently 

 uses tetracycline, an antibiotic deposited in growing 

 bone and teeth. Tetracycline has proven to be 

 reliable, but evaluating this biomarker is invasive 

 and expensive. Research conducted at NWRC 

 examined rhodamine B as a possible alternative 

 biomarker for the ORV program. 



Rhodamine B is a chemical dye that, when 

 ingested, stains the oral cavity and is absorbed 

 systemically into growing tissues such as hair and 

 vibrissae (whiskers), producing fluorescent orange 

 bands under ultraviolet (UV) light. Researchers 

 fed 18 raccoons rhodamine B and monitored their 

 whiskers and fur for fluorescence for 15 weeks. 



All raccoons exhibited fluorescence in their 

 whiskers. On any given sampling-day, an average 

 of 55 percent of whiskers sampled from each 

 individual fluoresced. Evaluations of whiskers 

 using a UV-equipped microscope and hand-held 

 UV lights were compared to determine if evaluation 



Rhodamine B is a chemical dye that, when ingested, stains 

 the oral cavity and is absorbed into growing hair tissues. In 

 raccoon whiskers, it produces fluorescent orange bands under 

 ultraviolet light. 



of whiskers can be done in the field. To a limited 

 degree, field evaluations were successful. 



At the conclusion of the study, researchers 

 conducted necropsies on all raccoons to look 

 at the systemic effects of the dye. Gross and 

 histopathologic examination of tissues revealed 

 only subtle lesions consistent with those previously 

 reported in wild raccoons. 



Fishmeal polymer baits containing rhodamine B are being 

 tested for use in the national ORV program. 



Developing Methods 25 



