Maltese in Heat?

Question
Hello we have a 8 month old maltese bitch.  Yesterday we noticed that her vulva was extremely large.  I haven't noticed any blood yet, but why is her vulva large?
THanks

Answer
well does she seem to be licking or cleaning it?
she may just be feeling some pain however if you notice it is excessive i would visit your vet because she could develop a problem with her ovaries
please be sefe rather than sorry.
please let me know how you get on.