Awwww..She's adorable!
First, I would go get Gumabones/Nylabones from the pet store before picking her up. They are her chew toys for fun and getting out anxiety. Not edible. They make some with little nubs on them, too but if she's a good chewer you have to use your judgement. Every time my dogs got excited, anxious whatever they went to their bones. When we brought our Bulldog puppy home, my son actually slept on the floor with him holding the Gumabone in his mouth LOL. It worked, though. That dog LIVED for those bones instead of going bonkers he went and chewed. Don't worry if she doesn't know what they are, every time she mouths you or something put the bone in there twist it around and she'll get it. IF she needs it she'll have it. Don't get the most teeny sized one, everyone buys too small a bone because they try and save money!
Get whatever looks the right larger size like "small" instead of petite maybe. I don't know I can't see her size LOL. I would put a shirt of yours down with her at night on her bed.
Even though she's been in your house before, I would take her for a walk before EVER going in the house first when you bring her home. It's a bonding exercise and she'll know that you are her new pack leader and look to you for direction once she gets inside. Get off on the right foot IMMEDIATELY. Of course it won't be much of a walk with the surgery but "simulate" it.
While there are different opinions with vets and food companies, I think you switch to adult food generally, when they reach adult height which for her should be about 10 to 12 months old in small dogs. They used to say 1 1/2 years old but changed it for some reason. HIgh cal I guess.
http://www.cesarsway.com/dog-care/do...Switching-Food
I would ask the shelter if she got the same food all the time and take a bag home with me to avoid gi upsets - but some shelters feed whatever they have and switch alot so it may not matter. I'd stick with a high quality puppy food for 12 months since she came in homeless and possibly had nutritional issues younger. IF she was homeless she potentially could have some food issues so the puppy would be more satisfying anyway. And it WON"T HURT an 8 month old. I actually think dogs won't overeat if they get a good food and balanced lifestyle but that's just me. (not including Labs hahaha).
Take a good long week or so to switch foods unless she has a bad stool (soft, unformed) from whatever she's on then switch faster. If dogs get Irritable Bowel, they switch them immediately.
I would not feed ANY edible dog treats. If you need to start that for certain reasons, you can do it later. Mother dogs don't "treat" their pups! And especially because you don't want to develop any food issues being picky. IMO an example of a good "treat" is as a "payment" when guests LEAVE if she shows any concern for visitors. They should ignore her when they visit if she's anxious - then PAY her when they exit.
You can walk her to the door to escort them out then they can offer the treat and IF SHE WALKS TO THEM, give it. NOT walk TO HER.
If for some reason she woolfs her food down like it's her last meal, I'd work right away to help her get over that, by holding her bowl chin level and raising it up making her take a few second breaks during eating. Also a bonding exercise.
Housebreaking, I'd take her out every couple hours at least every four if she can go that long. I would give her small areas to master not run of the entire house, for general purposes, anyway.
Be calm and
consistent and she'll learn everything you want her to learn. She's essentially a blank slate. Walks are the number one thing to help a dog be psychologically balanced, confident and happy. Even a back yard is a crate and there's basically no difference between a Chi or a Great Dane in most ways. That's my philosophy (I'm a dog walker/petsitter).
OH and no crazy stuff. Like when the doorbell rings she's allowed to sit a few feet away calmly and observe the guest but no charging the door, no jumping on people etc. Don't let anyone approach her either. Guests need to sit down and wait for her to go sniff them and still IGNORE HER. I tell them to dangle their hand down casually next to their leg and if she's interested in getting petted, she'll signal that. Then a gentle touch
to the chest NOT THE HEAD - THAT'S IT. No hiding either. Leash her up and bring her to sit on her bed or next to you on the FLOOR a couple feet away not all clingy on you.
Do not sit and hold her petting her all the time especially when guests come in. Put her on the floor. You don't want her to make up some crazy theory that they are a threat and you're "in it with her". If she shows anxiety or whines or something say "hey" or "shht" in a normal matter of fact tone, don't say "it's OK, baby, don't worry blah blah blah" because she doesn't understand English and hears "Be afraid" when she hears high pitched voices with weak energy. But you have to mean it and that includes STOPPING GUESTS from approaching her and intimidating her they really need to ignore her. It's what she wants - get to know people on her terms (her own pace).
This is really important - can make all the difference in a neurotic Chihuahua and a well balanced social one. And remember, no matter how CUTE she is, you own everything and it's not her job to make up imaginary "concerns". That's YOUR job and you don't need her help hahaha.
You can see all the videos from Cesar Millan The Dog Whisperer about Chihuahuas and other small dogs some of who were his biggest challenges. Like a mom who allowed her dog to bite her own kid cuz she didn't want to hurt the DOG's feelings! LOL That was
Bandit.
(most of the episode - hilarious this lady was one of the only people I ever saw really frustrate Cesar) LOL
http://www.youtube.com/watch?v=OiNR7Afmd4Q
p.s. I'm really not up to speed on all the dog food brands and options but there are usually "small bites" kibble for small mouths I think