Like Scott said an anti-allergen will help on carpet and upholstery. But I have read that it will take several months to rid a home of dander. It is not a one shot deal and gone. Dander like dust will travel threw the air and end up on all surfaces including heating and air systems. Anyone with a severe allergy problem will be affected by the least amount remaining.
I learned this the hard way many years back. I had a property manager ask me to go clean a carpet that was already cleaned by another company. She had sold this home to a couple and the wife had severe allergies, especially to animal dander. I went out to the job vacuum in hand and did the Marty 4 way vacuum deal on it. Cleaned as usual and collected the check. Well, a few days later the couple started moving in. The wife was in the home all of 20 minutes and had a reaction, swelled all up and watery eyes and sneezing. I get another call from the agent. This time I got the computer and did some research. Went back to the job with the Master Blend product did the job again. No check this time, but learned a valuable lesson.
It can take months sometimes to get rid of the dander completely. So now when I am called for a job that is dander related I can explain the problem and enlighten people about other potential problems other than just the carpet and upholstery holding the dander. Most real estate agents think you can give it a one shot cleaning and be done with it. But then again they have the same mind set when it comes to flees also.
