Yes, do consult the Vet if there are still symptoms. My neighbor used a topical treatment and his dog had neurological problems. Better to get a product from your Vet.
Get your guy to the Vet ASAP...They can flush his system with IV fluids to get the toxins out quicker and help the kidneys.....Hartz/Sergeants are very dangerous!!! Good luck & let us know how he's doing....Karla
Here's a link:
http://www.hartzvictims.org/tag/sergeants/
Make sure you bathe him in regular dawn dish soap (not dawn with bleach or anything like that). He needs to be seen by a veterinarian. I have seen animals pass away from the toxic effects of Hartz and Sargents products.