Lexi just had her 4th set of shots today and she had the lepto component in all of her shot sets except the first one which was given by the breeder. She has never had a bad reaction. About 2 hours after we get home from the vet her injection site gets sore and she isnt as playful as usual, but after some infants benadryl or baby asprin she perks up a little. However the next morning she is completely fine! Just keep an eye on him and he should be fine!