strange behavior

Question
QUESTION: I have a 7month chihuahua and he has never asked like this before.He has been acting weird around our 10 yr. old sheltie. He sniffs her butt,and will not leave her side. He whines when you take him away from her or if he can't see her. This is very upsetting to my kids and I. Please help going crazy.

ANSWER: So he likes to be by her side? Is he neutered? Does she seem bothered by it?  I don't understand how it is upsetting though, could you clarify for me? Is she spayed? Any other behavior other than that?

---------- FOLLOW-UP ----------

QUESTION: Yes,No he is not neutered.He is going into get neutered asap. No she is not spayed,yes she is snapping at him,trys to run away and we try to keep them apart as much as possible. Because he jumps on her and I'm afraid that he will break her hips. If you separate him from her he whines and whines and all the two of them do is bark.She barks at him and saps, but he just won't leave her alone. I don't know if it's the way she smells to him or not.He sticks his nose in her butt and other part. He also keeps on licking her there as if he was cleaning. This is my first chihuahua so not real understanding on there behavior.

Answer
There is your answer, neither dog is neutered/spayed! While I do not believe dogs her age go into heat, this little guy is ready to procreate! Please make sure he gets neutered ASAP before anymore of these actions become engrained. His hormones are raging and he is smelling a female who is in all words "intact". It's natural! So take a deep breath and try to relax :)

The longer you wait to neuter the worse he will get, not to mention marking/spraying your house with urine will be coming soon, and that is NOT fun at all, so since you said you're taking him ASAP, then you have not need to worry.

Good luck! I hope that helped.