Hi Alex, I'll just add my 2 cents if you don't mind :) I have 6 cats, 2 of
which are female so i understand your situation. Ok, number one. get the
cats desexed. It makes no difference whether they are littermates or not,
cats, especially females, will have probs at around the age your two are.
they are adults now, and in normal cat situations, (ie wild cats) would have
their own territotries, would not be on speaking terms, and would be raising
kittens at this age. You will have a 'dominant' cat and an 'underdog' so to
speak. Having them desexed will make them a lot less agressive about this.
With my two girls, the older one dominates the younger, skinnier one, and I
do have to watch meal times carefully. With meal times, if I were you, I
would set up a 'meal area' in your living area that is out of reach of the
dogs, ie on a bench top or cupboard. Have set meal times, and make this time
a 'family time' where you can supervise your cats eating, and you and your
girlfriend can spend some time with them. Your cats and your dogs are your
family, and it's not good to have this separation. However, I wouldn't even
leave cats and dogs unsupervised. If the dogs are chihuaha size, you could
eventually leave them unsupervised, but only if the cats have plenty of
above ground routes where they can get away from the dogs. Do you have a
back yard area, or perhaps a balcony?? It might be worth your while to look
into an outdoor enclosure for either your dogs or cats. If you have a
backyard, you could erect an addition to the cat's room that they can access
from their room with no help from you, ie through a window. This will
improve your cats life and happiness 100%, as this will give them both more
space, and also something to occupy their minds. Just make sure they have a
place to get out of the weather. Pretty much the only thing you can do here
is desex your cats (very important, decreasing cancer risk etc etc) and
allow them out of the room when you are home. Let them mingle with the dogs,
but only while you are actively supervising them (ie not when you are
sleeping/showering). Hope things get better. Multiple animal households are
a challenge, but are worth it!!

No, it won't be more stressful for them to fixed now.  Its more stressful to
them to keep coming into heat.  Don't they drive you crazy yowling to get
outside when they're in heat? Please get them to the vet, there's no reason
for them to remain unfixed.  What if one of them got outside and got
pregnant? Believe me they'll try their darndest when they are in heat. Then
you'd have to deal with dogs, cats, and a whole litter of kittens to find
homes for.

What is the problem between the dogs and cats?  Have the dogs EVER harmed a
cat?  How do the dogs act around the cats?  Curious and playful?  That's
pretty normal.  My dogs always wanted to figure out what these cat things
were.  Then they wanted the cats to play.

You should be able to find several web pages covering how to get dogs and
kitties play nice.  If you take things slowly, there's no reason you can't
teach the almost any dog how to behave around the cats.  But follow the
advice on the following web pages just in case - there are a few dogs should
never be around cats.

Here are tips for dog/cat introduction:
http://petcaretips.net/dog_cat_wont_get_along.html
  AND
Here is a good site for lots of other cat behavior questions:
http://petcaretips.net/cat_care.html#Cat%20Behavior

I did some suggestions from my own experience, but these web pages cover a
lot more.
Good luck, and just be patient on any dog/cat introductions.

-- maryjane

No, not at all.  Going into heat repeatedly and being frustrated at not being
able to do something about it can be making them aggressive.  Not only that,
but no more howling.  They will be much nicer pets when you get them done.
It also reduces your cats' chances of getting mammary cancer and tumours of
the ovary and uterus.  I've actually seen a semi-feral cat go from a snarly,
aggressive cat to a calm, playful cat once spayed.  

Oh, that's great that the dogs are not super aggressive.  Sure, you can
integrate them.  Lots of people have multi-pet households.  I don't have one,
but I did when I was younger - a german shepard with two cats.  He was okay
with them but nipped once in awhile at their necks gently though, not hurting
them.  It's going to take time though and patience.  Definitely try and
integrate them (sorry, I was under the impression they were aggressive
because of your other post where you mentioned they "like the taste of
kitties", now I see you were joking - that's why I thought they might not be
able to live together).  Once they all start living with each other, it'll
make things so much easier for all of you and then the "family" will all be
together.