Copyright infringement

I was surprised to see a picture of MY DOG from MY website being used by someone else today on an advertisement after my friend told me about it. It seems that certain people do not seem to know or respect other people's work or property.  I do not tolerate and will not tolerate such things in the future.  I have asked the person to removed MY picture and he is to never use it again.  He even had the cheek to put his water mark on my picture.  I will not hesitate to take legal action should anyone else try to do this again.  He was using Daisy's picture to promote his puppies.  If you come across any of my pictures being used by someone else on an advertisement, please let me know and I thank my friend for alerting me on this today.