Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry that you have been waiting for a response, but your requested expert isn't online which delayed your question coming up on the list for all to answer. I would like to help if you are still interested in an opinion.
Blu Kote contains gentian violet, sodium propionate, acriflavine, urea, and a high concentration of isopropyl alcohol. All of these are horrible tasting and gastrointestinal irritants and isopropyl alcohol ingested in large quantities can be a neurotoxin and cause incoordination, changes in mental alertness, and coma/death as well as liver damage.
The amount that your pup ingested by licking his paw was probably enough to give him a horrible taste in his mouth and cause irritation to his tongue, but is unlikely to be enough to cause more serious damage.
You might try flushing his mouth again with cool water to remove as much of the product as possible and get the taste out of his mouth.
Then you might want to feed him a soft diet (canned food or add water to his dry food) for the next couple of days.
That should be all that you need to do.
In the future if you use this product use an elizabethan collar (lampshade collar, cone of shame) so he cannot reach the area to lick it
Please let me know if you have any further questions.