Two males spraying in the house

Question
In our home we have a 5 year old female (8lb) Shitzu (not spayed), a 4 year old (10lb) male Shitzu (neutered)and a 10 month old (30lb) Cockapoo (not neutered). From the beginning the Shitzu's have wanted nothing to do with the Cockapoo which was not too much of an issue. With 6 people in our home we just spread the affection to all of the animals. The problem: For the past several months the 2 males been spraying ALL OVER our house. They lift their legs on everything from furniture and freshly laundered blankets in the house to our female dog (when outside).
I have tried everything, positive reinforcement, extra attention, crating etc. I have cleaned the whole house (not a small area!)with first, pet carpet cleaner, then sprayed it with a pet odor neutralizer which was to prevent them returning to the same spots. All to no avail, the spraying continues!
My husband is going nuts and I have agreed that this can not continue but am heartbroken at the thought of finding a new home for our Cockapoo. Please help!
P.S. We plan to have either the female Spayed or the male neutered and wondered whether this may help resolve the issue?

Answer
Hey, Michelle,

This is a tough situation for you and your dogs. I'm really sorry to hear about it.
Dogs "mark" for a number of reasons. (Cats "spray," by the way; dogs "mark.") The main reason is that it's a way of reducing internal tension and stress. It sounds like that's a major part of the problem here. The two males don't really like each other, and they're "in competition" (hormonally speaking) for the female's attention (so to speak).
To reduce stress I generally recommend giving a dog lots of hard, vigorous playful exercise, particularly games like fetch and tug which use up the dog's predatory energy very quickly. When dogs in a multiple-dog household aren't getting along, I also recommend that the owners take them on long walks together, on lead. By doing this the dogs can get the feeling of moving together, side by side, the way wolves travel when on a hunting expedition, or the way military units are trained to march together. It increases feelings of group connectedness and comeraderie.
You can try those things. I'd also recommend using fetch and tug to teach basic commands like heel, down, and stay. (You'd only have to spend about 15 mins. a day per dog, doing the training.)
I'd also hand feed the two males outside, using a pushing exercise, where you hold the food in one hand and put the other hand against the dog's chest. As he eats you gradually pull the food hand slightly away so that the dog has to put pressure against your other hand in order to eat.
I can't say for certain that any of this is going to reduce the marking behavior of both males, but you could try it for a few months (if you think you can stick it out that long). Just remember that the marking is an indicator of internal stress, and that the dog's system is designed to get the maximum reduction of stress through hunting activities (hence the games, the long walks, and even the pushing exercise, which increases a dog's feeling of having to use his prey drive in order to eat every day--in other words, the two males need to "work for a living").
If these exercises don't work, my first choice would be to neuter the female. There are few pros and many cons to doing the surgery, but with females the pros slightly outweigh the cons.
I hope this helps!
LCK