cat urinating/power struggle?

Question
I have a coon cat that is approx. 7 yrs old.  I have a female cat that is his buddy.  My fiance and I now share a home.  He came with a female cat and a male dog.  I recently have had a baby as well.  Everyone is fixed and he has been an absolute angel til the move in.  We all have been living together for a year now and he is starting to urinate all over the house.  I am thinking this is a power struggle between him and the male dog.  Since the birth of my son, he has now increased his urinating- marking everywhere, even my baby's toys.  What is making me wonder if it is something more, is that this evening he is drooling excessively and visibly marking territory.  Is he being more defiant then anything or does he have a urinary infection?  He has an appt. with the vet tomorrow.  He has always been is great health and I wonder if his peeing will end if he is separated from the male dog.  I am not sure what to think, suggestions?

Answer
Cats and dogs will usually not fight over territory by marking.  They have different pheromones, and are different species, so generally if they are going to have a territory issue they are going to fight.  Cats especially can be very sensitive to changes in the household, such as new pets, people, or moving to a new house.  Improper elimination can sometimes be due to stress, but you definitely want to rule out a UTI first, as that is the usual cause for such problems.  Taking him to your vet is the smart thing to do, and they should be able to get a urine sample to run and see if he has crystals or an infection which could be bothering him.

Amanda