How Can you tell if a lab is purebread?

[BIGINNER]

i know you can't tell 100%,  but what are the main factors to look at if a lab is purebread.
i had a lab come into my yard a couple days ago, and he hung out with us all day. he slept on our deck for several hours. i fed him, and my kid should couldn't get enough of him.  the dog is very well behaved. and is very beautiful.  He looks like a puppy still. looks like he is maybe a year old.  he responds very well to all my commands, so i'm guessing somebody has been training him. and he is a natural retreiver.
well he is not leaving and none of my neibors (even all the people down the street have no idea who's dog it is. we decided that we will try for a while longer to find his owners, and if nobody shows up we might have a new dog join our family.

Now back to my question. he has a nice blocky head and otter tail like all labs. and i am pretty sure he is purebread. what else should i be looking at to see if he is pure bread?   

[BIGINNER]

purebread or not.. Does it matter?.. Dog likes your home... What would decide you keeping the dog?...

if owners don't show up we are going to keep him weather he is or isn't purebread.  my kid loves him my wife loves him, even my other dogs love him. and he is very handsome.  i'm just curiouse.  i'm about 99.99% sure he is a purebread and somewhere someone is missing one hellova dog.

[ghosthunter]

I would have him scanned. If he is as nice as you say he might be microchipped .
No sense letting the family fall in love before you know for sure.

[BIGINNER]

I would have him scanned. If he is as nice as you say he might be microchipped .
No sense letting the family fall in love before you know for sure.

yeah, thats our next step.  it might be a little too late on the getting attached part, but if we find the owners we will get over it. 

[RifleRidge]

I would have him scanned. If he is as nice as you say he might be microchipped .
No sense letting the family fall in love before you know for sure.

  

[bearpaw]

I would also post a lost and found ad on your local paper, radio, or craigslist. There might be a family that is heartbroken out there somewhere.

[Kola16]

What color 
If he is black or brown, then look for bolo hairs (not sure on the spelling). They are white hairs under they paw 

[h2ofowlr]

I look for birdie labs that aren't to high strung.  Some pure breed field trial dogs are to much for me.  You only need the papers if you plan on showing/ field trials or breeding.  I have had some great dogs that weren't pure breed.  Extra branch in the family tree helped out.   

I wouldn't worry as longs lab doesn't have pit or rot in him/her.

[BIGINNER]

I look for birdie labs that aren't to high strung.  Some pure breed field trial dogs are to much for me.  You only need the papers if you plan on showing/ field trials or breeding.  I have had some great dogs that weren't pure breed.  Extra branch in the family tree helped out.   

I wouldn't worry as longs lab doesn't have pit or rot in him/her.

definately no pit or rot in this one. i might post pictures of him if owners show up,

[Stilly bay]

there are some " pure bred" labs that don't look too pure to me. any white on its body would be a good giveaway, ear set, and even spots on its tongue.

[Maligator]

A couple quick & easy checks for confirmation can be done...it's not a guarentee but some things to look for are:

Ears should pull to just the inside of the corner of the eye

Tail should be "otter like" in appearance and when pulled down shouldn't go below the hock of hind leg

Should have a slick outter coat along with the softer unlayer thereby having the double coat.

There are more confirmation checks you can find @ the AKC website but these are a couple easy ones to check like I said. Either way, if he's a good dog then it doesn't really matter 

[jeepasaurusrex]

   

[benbo30]

   

   

[cryfowl]

Labs vary in color.  Just because it has a spot or off colored hair doesn't mean it's not pure.  Look at a black bear with a white chest patch.  Does the patch mean its momma hooked up with a polar bear....No.  Same goes for labs.  All it means is that it won't be a show dog.  Has no bearing on it being pure.

[Kola16]

Labs vary in color.  Just because it has a spot or off colored hair doesn't mean it's not pure.  Look at a black bear with a white chest patch.  Does the patch mean its momma hooked up with a polar bear....No.  Same goes for labs.  All it means is that it won't be a show dog.  Has no bearing on it being pure.

Except the bear analogy is kinda comparing apples with oranges  But many pure labs have white spots.

Should have a slick outter coat along with the softer unlayer thereby having the double coat.

Sorry...that is a pretty poor determinant too