Has anyone ever had their puppy have a reaction to a vaccination? My puppy had a DHPP vaccination and a dewormer pill at around 4:00 pm today. It has been 5 hours and my puppy is very hyperactive and aggressive tonight. We have tried running him around outside several times. He can't seem to settle down. I have heard of dogs being lethargic after vaccinations, but not hyperactive. Any help is much appreciated...... He appears to be breathing fine and isn't swelling at all, but he just can't seem to settle down.