Our dog got bored and went chew toy on a blue ink pen. It got all over him, as well as some on the carpet.
We let it sit quite a while (weeks) because we couldn't figure out what to use on it. I was real concerned about using something and making the stains spread.
As a solution, I used some rubbing alcohol on a towel and it completely removed the stains from the carpet. I was very impressed with how it came out.
We read about a lot of different things to use, but we ended up going with rubbing alcohol and it worked great with our carpet. Just thought I would pass that along in case anyone else walks out to find a blue dog.
2006 Monaco Knight 40PLQ | 2011 Jeep Wrangler Rubicon Unlimited