Sorry, but I don't really trust anyone in the game to not potentially be an android at this point.
The wording thus far has been that the Dog cannot die- for story reasons.

Now. Let's look at it this way.
A dog wanders into a settlement.
No one is really going to notice that dog, unless the dog is rabid, or a complete [censored] head.
So, they can hang out, really anywhere. Indefinitely.
A person? "Hey, why has that guy been standing across the street for a week? It's like he plans to stand there, indefinitely, or something! We need to keep an eye on that guy."

So... We have this dog. It's just hanging out.
Here's you in this bright vault suit, all naive and ignorant of your wildly changed setting. He seems friendly, and you are lonely. (it seems Codsworth's programming doesn't really allow him to process what has occurred).
But the dog is really programmed to wait until someone comes out of a vault and follow them. Data does show, many people in the pre-war world considered the dog to be man's best friend. Maybe, after you've formed a really good "master/dog" relationship, they will attempt to lead you somewhere.
"What's that, Lassie? Timmy's stuck down a well?" Only the well is the Institute, and you wind up being Timmy, after they capture you.

No. The dog can't die because no companion can die. It's not dog special.

And you are not forced to take him as companion

Honestly its a case of you're looking into it to much, Todd remarked the dogs "immortal" because a) he used it as a readly example how the companions in 4 are unable to die a lot of people who played 3 where frustrated how easy dogmeat died, so he wanted to ease there concern that there be similar fuzz with this incarnation.

An android, by its very definition, cannot be a dog. The 'andr-' prefix means man. Technically speaking, a robot designed to resemble a human female is more accurately called a gynoid. If I had to venture a guess, I'd say a robot dog would be a...canoid?

None of the companions in New Vegas was mortal if you played on normal. Cant remember them being Androids.

Everyone knows a dog would never betray you. Even if programmed to it would just explode as its programming clashed with its basic instinct.

Uhh unless there is a treat involved, or a fuzzy slipper, or something interesting in the trash. Never betray You I say.

Last words before 2-caps taken prisoner.

"Spot you mangy S.O.B, you sold me out for a can of Dinky- Di ? (dog food from mad max)

The dog doesn't look like Rex to me.

Looks like 'everyone is an android' at this rate...

(except the androids)

Cool speculation

Upgrades for the dog late game aswell maybe

I hope we can name our doogie because I will the poor buddy 'Todd" so he can do what I tell him to do, at that moment when I say it.

I wouldn't have a problem with an android dog, but TBH, I really don't think the dog in FO4 is one. I'm also, in a way, happy that he can't die. Companions in general have a tendency to rush headlong into danger without ever thinking of the consequences of running in front of my gun(s) while I'm firing them.

BTW: Timmy never really fell down that well, you know. He fell in alot of things, but never a well.

What if codsworth is a android?

Mmm, fresh meat! I think that some people would notice it.

You aparently had a dog pre nuke so to me it's logical that cogsworth just took care of it and all of that dogs puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies puppies deep breath .....panting I think you get the idea. Heck it's posible that cogsworth played back you and your spouses voice files from memory just to keep the original dog and its decendants amused over the decades.

Aaaaaannnnnnd now I have another mod idea I'm going to put into the game if it's not already in...... Roving bands of dogs escorting mr handiest that were reprogrammed with you and your spouses voices.......

To be followed be encounters with people who recognize your voice......

You mean Codsworth too?? NOOOOOO!

Isn't there a perk in FO 3 called "puppies" or something like that which makes one of Dogmeat's puppies appear at the vault if Dogmeat is ever killed? Maybe they did away with the perk and just made him come back to life.

Edit: Yeah, it's called Puppies! and was added with the Broken Steel DLC.

All I get from this thread is that you are all svckers- a droid dog would fool you all, tugging on your heartstrings.
Then it's, BAM! skeleton city.....

Maybe, before my PARTNER sold me out, Not now.

Its a dog eat dog world, an from where I am sitting, There just ain't enough dogs!

or a dogs just a dog.

If it means anything, I think Codsworth may also malfunction and attempt to kill us, or that someone reprogrammed or reprograms them at some point.

Maybe it is just my hope that there is a large betrayal in the story, somewhere (other than the betrayal some fallout fans feel)

I wish he was a Cyberdog like Rex from FO:NV.

I think the idea is a bit of a stretch, but not so much of a stretch that it's impossible. After all, In the most recent fallout game we had a robot dog as a companion. I'm assuming that the dog will rather just be an essential NPC that crouches for a few moments when KOed.

This is kinda why I like the idea.
As I said, I am hoping for a twist.
I don't argue that the dog is most likely just a dog. But my imagination says that's boring.

I'm expecting a twist.

I don't think it's the dog, but I also don't wanna think about it too much. For the fear that I might guess right!