My question is why are you looking for something so incredibly tiny? Cats are much larger than what you're looking for in a dog and yet they're still totally 'portable'. My cats are in the 16 pound range. They're big for sure, but even an average cat is around 10 to 12 pounds. Dogs of that size are just as portable. My concern is you're looking for the super tiny Chihuahuas and you can run into a lot of problems, as someone else mentioned. If their blood sugar drops while you're at work or out shopping, they could crash and die before you're home. A lady here locally that I'd helped get her dog spayed lost hers because of that.
I've got five Chihuahuas in my house right now. My girls are 14 and 15 years old and weigh about six pounds each. They're very small. I can't imagine anything smaller than that. Chis are active by nature and I'd be worried that it would try jumping on or off furniture when I wasn't around and get hurt. And I wouldn't want to have to leave it locked in an xpen or crate all day just to keep it safe from life. That would suck for a dog. My other guy is a chi / terrier or minpin mix and around 14 pounds and still totally portable. He gets carried all over the place. My foster Chihuahuas are in the 10 to 12 pound range and a great size. The female I think is a chi / Pap mix. The boy might have some Peke in him. They're both long hair. My baby girl was a long haired chi and weighed 14 pounds and she and I were never apart. She traveled every place I did, with the exception of shopping and such. For me, she was more than perfect.
As a side note, every single one of my Chihuahuas, including the small girls, were all rescues that would have been euthanized in the shelter. Check Petfinder. It's a great source for finding your new family member. As a rule, shelters are much easier to adopt from, ask fewer questions. If your cat wasn't spayed / neutered and kept up to date on everything, you might want to go to shelters first. If you did a great job as a cat owner and have a good vet reference, you can easily adopt from a rescue. Keep in mind rescues put a lot of time and money into these animals and their goal is to ensure the perfect home for the pet where it will never be homeless again. They ask a lot of questions, generally want to do a home visit, etc. Some can be a royal pain in the backside, and if they are feel free to move on, but expect all of them to at least ask for vet references. Some won't adopt out of area, but the ones in the south generally will. I'm in middle TN and have adopted to people in Maine, Utah, Virginia, West Virginia, Indiana, Kentucky, Georgia, Florida, etc. And southern rescues are generally much more reasonable on fees as well because they didn't have to pay a fortune in transport costs to get an animal to their rescue and our vets are cheaper as well.
If you have any questions I'm happy to help.
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