Workers exposed to laboratory animals are at risk of developing asthma, rhinitis, angioedema, conjunctivitis, and urticaria. Approximately one in five scientists and technicians handling small animals will develop laboratory animal allergy symptoms within three years of employment, many of whom will have severe symptoms requiring a change of occupation. Individuals suffering from allergy to environmental allergens, such as pollen and ragweed, are more likely to develop allergic reactions to animals, and are more likely to develop asthma. We report a case of life-threatening anaphylaxis secondary to a rat bite in a laboratory research director with known allergies to rat urinary protein. While rodent bites are common in research settings, such severe reactions are extremely rare.