[ladyjane]

I honestly don't think either of these meds would cause lethargy. I have used both for a number of pups with no ill effects. The Convenia could cause GI issues as could the prednisone. The prednisone would be more likely to cause her to be more active. Maybe she is just resting since it sounds like she was really itchy prior to the meds? They also should not be a problem when given together.

You really should call the vet about this to be on the safe side. Since it is evening, I don't think any harm would come to her if you hold the dose and call the vet in the morning.