His head is deer shaped.
In the first picture, it is difficult to tell whether or not he seems to be a full Chihuahua.
In the second picture, it is my opinion that he seems to be a full blooded Chihuahua.
Head shape could definitely represent if a Chihuahua dog is pure bred, or a cross-bred dog, but there are MANY pure bred Chihuahua dogs with Deer shaped heads.
The only thing that head shape dictates is whether or not a dog can be shown. Only Appleheads can be shown because the AKC dictates that the head of a Chihuahua dog must be apple-domed and that its muzzle must be moderately short. The Deer headed Chihuahua doesn't fit this description. None of this really matters though for people who don't show. Some people prefer the deer head shape. Also, here's my two-cents on that subject. Dogs change over time, especially due to the fact that people breed them to "standard", (and I am quoting this from several people that show dogs nearly word for word) to contribute to and perfect the breed. Well, in doing this, it not only cosmetically changes the way the original Chihuahua dog looks, it is a road to essentially no where because how can humans be the judge of what the perfect Chihuahua dog is? What exactly is the "perfect Chihuahua dog"? Some evidence shows that the original Chihuahua dog from the state of Chihuahua, (the state where my family is half from) was not nearly as dome headed and short muzzled as today's Chihuahua dog. How is that perfecting the breed? Changing it more and more from what it originally was?
Anyway, that is just my rant. It's a BIG subject for me but please, by all means, if you intend to show believe me when I say that many people find it to be a rewarding experience. Do not let my ranting deter you.
As for your dogs weight, it seems absolutely normal. Some Chihuahua dogs are bigger, some are very tiny. Some grow a lot into adulthood, some don't grow all that much at all. It all depends on the dog, just like humans!
I hope this helps you.
Last edited by PrincessCupcake; 11-21-2011 at 02:50 PM.
Reason: grammar, trying to correct as many mistakes as possible