[Chong]

One of my two pups had an allergic reaction to Pro-Heart6 several months ago. As soon as we got him home from getting the shot, he started to have muscle spasm and would go around and around, lie down, then jerk himself up and do it all over again. His heart was beating fast and his nose dried up.

We went straight back to the vet and she gave him a steroid shot and put him under watch for a few hours before sending us back home. The vet said that it was only the third reaction they encountered, but needless to say, our other puppy will also be on monthly pills, although she hasn't shown any adverse signs.

[Salamander]

My baby had the fast heartbeat too.
It settled down after an hour or so and the vet didn't it was "connected" to the shot.
That's her first and last dose of that stuff.