Why don't you spay your dog? I have 2 female dogs and they are both spayed. It is very healthy for them to get spayed if they don't have sexual activity.
At old age they can develop all kinds of problems because they never stop going into heat 🙁
I think this is a better option than keeping the poor dog in a cage for 2 weeks twice an year.

We usually castrate the dogs in a humane way to control uncontrolled breeding. This should be done only when you are sure you don't want more progeny from the dog you want to castrate. This is done using a special rubber band with a small aperture. It is expanded to slip the scrotum in and then it is released to grip the capillaries. This kills them slowly and finally the testicles are severed.

My parents had a female dog that was not spayed and at 13 years old she started having false lactation and then mastitis on a regular basis. On top it had other problems with the ovaries as well. It died when it was 16 🙁
I don't consider spaying inhumane.

I would rather spay a dog than stick her in a cage. When I failed to spay mine at the proper age, problems ensued. First, the large dog next door came home in the car with his folks, found me in the unfenced front yard with my small female in heat and was all over me trying to get to her. He was friendly about it, but his folks were embarrassed and so was I. Second, we had to evacuate for hurricanes and my small female was in heat again on both occasions. The first time, I wanted to hug my cousin, but didn't realize my dress was covered in blood spots from my dog being in heat and her riding in my arms. My cousin remained across the room and wouldn't hug me for obvious reasons. The second time, we evac'd to Dallas and I managed to get temporary work with some companies I had a work record with. When I got home late from work one night and was walking the dogs, we ran across a coyote in the shadows, who would very much have liked to have its way with my little dog in heat. Fortunately, we were able to return safely to my friend's trailer without incident, but I wouldn't want to have that happen again. So in the future, I plan to be more responsible and spay my dogs in a timely manner.

I agree with [USER=96]@ioana_mv[/USER] Spaying and neutered the dogs are much better for them in the long run. My x-husband's dog got cancer in his testicles because he wasn't neutered, and now finally had to get the testicles removed.

My dog got his done after he turned 7 months old. He also behaves better, and doesn't run away to look for females.

There are benefits, especially to active large-breed dogs, to keeping their hormones. Here's a good link: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0055937 - The study was done in golden retrievers but there is work being done to confirm the findings in other breeds.

Our current dog came to us already neutered but if you're against neutering or full spaying there are other options. There is something called an "ovary sparing spay" or OSS, which removes the dog's uterus, cervix, and tubes while leaving the ovaries and hormones intact. The female still goes into heat but it is no longer messy and she cannot get pregnant. For males, dogs can get a vasectomy (like a human would get) instead of a castration.

My mom keeps intact dogs that she does not breed. When one of the females goes into heat, the female wears those panty things that they have. The males wear belly bands. They are not left together unattended during any part of the heat but they can socialize with those things when supervised. She takes them out for potty breaks separately. During the actual fertile period (which is only a few days out of the heat cycle, not the whole thing) is the only time she keeps the fertile female completely separated from the other dogs. You have to be aware of changes in personality during the heat cycle and changes in how other dogs react to a bitch in heat. This can create conflicts/mild fighting in an otherwise happy group of dogs so supervision is important for more than preventing pregnancy.

It is best to spay dogs if it's not intended for them to have offsprings. On the other hand, you can also consider donating the dogs to other dog lovers if you do not want the concept of spaying your dog

I always make sure to have a buyer before getting my female dog into breeding and give birth to new puppies. 

If you don't do it that way, it's always going to be too much job for you to take care of all of them. 

Having your dog spayed is the best way to prevent them from getting pregnant. It's a decision you need to make on time and carry it out when the time is right for you. Both of my dogs are spayed and I'm okay with it.