Adult dog behavior

Question
I have a black lab/chow mix female, approximately 3 1/2/ years old.  I have had her a little over a year.  I also have 4 cats - 2 female, 2 male.  Just recently my dog has begun "humping" one of the female cats.  (I have had the cats longer than the dog).  What does this mean?  All are neutered/spayed.

Answer
Hi Brandi!Your female dog is in heat right now.Thsi will last for approximately three weeks.It happends two times a year-autumn and spring.She will hump other animals,but she will not have babies because they are all neautered.Hoep this helps lots!  Nicole.D.