Trust me, I know all about the heartache. You think breeding is just all fluffy cute puppies, but it is so much more! Chi's have really small litters, average is just 1-3. I have lost a puppy in all but one of my litters. My most recent litter I lost a tiny male. He is the one the is laying in the palm of my hand. He was only 6oz at 6 weeks and had had quite a few bouts of hypoglycemia, and to top everything else off he developed hydrocephalus and had to be put down at 6 weeks. It's always harder when they are older. I had another 6 week old have an attack of some kind. We rushed her to the emergency vet, and they were able to bring her back, but she then passed on a few minutes later. In the last c-section I had one of the puppies didn't come out in very good shape, and I found him dead in the whelping box 2 days later. If they don't make it, it's always easier to let them go before you have a bond formed with them.
On the other hand, you get to witness miracles. Also in my last litter I had a little male pup that had fading puppy syndome. I stayed up for a week straight bottle feeding him. Once i finally got some weight on him, he develped a horrible eye infection, and his entire eye socket swelled under his still shut eyelid. Somehow this amazing pup came through everything and turned out to be one of the sweetest puppies I have ever seen. He just went to his new home last weekend.
Alot of people just get into breeding looking to make a quick buck off their two pet dogs. They figure dogs are animals, and can handle the breeding, pregnancy, whelping, and rearing all on their own. I am very against this type of breeding. If done correctly you will lose thousands of dollars on every litter. And it can be one of the most heartbreaking things you will ever do. But if you are truely breeding for the betterment of the breed, and love your breed it will all be worth it. There is nothing like seeing one of your puppies earn their championship and knowing that you really made a difference!
Oh, and yes, chihuahuas do come in merle! Alot of people don't know that chis can come in any color. It actually states in the standard "any color marked or splashed". Alot of people just think they come in shades of brown, not so! And if anyone ever has any dog/ breeding related questions I will be happy to answer and help to the best of my abilities!