Rita had a reaction to the Lyme's vaccine about 2 years ago. Broke out in horrible hives all over her body, pale gums, panting very hard. The Lyme's portion of the DHLPP (Distemper, Heptatisis, Lyme's Disease, Leptospirosis, Parainfluenza) is from what I've learned, the most common one that causes a reaction, as well as the Lepto portion.