Puppies are 4 weeks old.

I can only tell you what I use - I'm not a vet. I sprinkle 1/8 tsp powder on each meal for a litter of about 8 pups. I put 1/8 tsp per gallon in their water. Good luck!

On this site, scroll down to the second half on clostridium.
http://www.vin.com/VINDBPub/SearchPB/Proceedings/PR05000/PR00425.htm
Tylan:

over 50# 1/4 teaspoon
50- 26 # 1/8 teaspoon
11-25# 1/12 teaspoon

safe to use BID and for several months