Shannon,
First off, Thank you so much for taking this appearent abused B in. He clearly has not been treated right or that scar wouldn't be there, in that manner. I think you might be right on, that someone tied his mouth shut, maybe to prevent him from howling or maybe even biting, although it doesn't seem as if he is a biter. Post some pics when you have a chance I am sure more peeps will chime in.
I agree with Basenjimamma, they probably tied his mouth shut to stop him from howling… Did you know that Basenjis can scream loudly? Maybe they were leaving him tied up or shut in somewhere he did not want to be and he was screaming/howling... This is so terribly sad to think of.:( I am so glad to know he has a good home now. He may have a few quirks from the abuse in the past he hasn't presented with yet, but for the most part he sounds like a terrific little guy!!! Please take pictures of him now and then get him all healthy and take lots more pictures. You will be amazed at the results!!!:D
Can you tell how old he is? I can't imagine him being too old if they mistreated him like that. He probably was howling and whining, and as he wasn't fed properly, I don't think the old owners would put up with it for too long with them having to be so cruel and tie him up.
I'm just glad he's found someone who wants to take care of him properly, and come on here to get all sorts of advice. You probably want to get the fanconi test when he settles down a little. It's a genetic disorder that is more prominent in misbred dogs, as it's easy to test for and not breed affected dogs.
Also, be aware that if he is undernourished he may well be underactive as well. As you increase his weight, his energy levels may change; he may get into more mischief and may challenge your authority a bit.
If you are prepared, none of it should be a problem.
My dog has scars on him and he is not abused. He is just a poo poo head with other dogs and also when he was a pup he tried to dig his way out of the crate. Sometimes the rubbing on the face against the metal bars can cause hair loss and eventually scarring. Since he is so personable with people and not afraid I am not so sure I would jump to the conclusion he was abused. That does not mean he wasn't, but every dog that someone gives up with a scar was not neccessarily abused in any way. I am glad you have him now and it won't be an issue.
My dog has scars on him and he is not abused. He is just a poo poo head with other dogs and also when he was a pup he tried to dig his way out of the crate. Sometimes the rubbing on the face against the metal bars can cause hair loss and eventually scarring. Since he is so personable with people and not afraid I am not so sure I would jump to the conclusion he was abused. That does not mean he wasn't, but every dog that someone gives up with a scar was not neccessarily abused in any way. I am glad you have him now and it won't be an issue.
I was thinking the same thing…maybe he wasn't abused. He may have been anxious in his crate and cut his face on the bars. The other thing is that some head halters if not fit correctly dig in and wear fur & skin down. Doesn't mean he wasn't abused, but there might also be another explanation.
It is hard to second guess what the cause is and what the marks look like...maybe post a pic when you get a minute.
Oh, and to Jinxed...welcome to the forum! 
That is true, and lets hope that is what it is and that he hasn't been abuse.
My dog has scars on him and he is not abused. He is just a poo poo head with other dogs and also when he was a pup he tried to dig his way out of the crate. Sometimes the rubbing on the face against the metal bars can cause hair loss and eventually scarring. Since he is so personable with people and not afraid I am not so sure I would jump to the conclusion he was abused. That does not mean he wasn't, but every dog that someone gives up with a scar was not neccessarily abused in any way. I am glad you have him now and it won't be an issue.
Good point. I know my B has a few spots around his nose and jawline that get really pink sometimes. He didn't have them when I first got him, but the few times he has been crated he has gotten very frustrated (chewing and trying to get out). I think they may be from that as well. Exactly why I cannot crate him anymore for more than 10-15 minutes.
First off good on your husband for taking on this boy, i'm sure he will bring you both many happy years together:D
Another possible could be that he got his nose stuck in a tin can or something, though I suppose you will never really know for sure what caused it.
I was thinking the same thing…maybe he wasn't abused. He may have been anxious in his crate and cut his face on the bars. The other thing is that some head halters if not fit correctly dig in and wear fur & skin down. Doesn't mean he wasn't abused, but there might also be another explanation.
It is hard to second guess what the cause is and what the marks look like...maybe post a pic when you get a minute.
Oh, and to Jinxed...welcome to the forum!
I was thinking the same thing about a possible head halter…would like to see some pics to help evaluate 
Scars do not necessarily mean he was definitely abused - my puppy has a scar on her ear where she's been scratched by my cat, a couple on her snout where she stuck her nose where it didn't belong with other basenjis, and one on the top of her snout which took off some of the black on her nose leaaving a pink line, because she grew quickly and when she was running full out didn't remember she doesn't fit under the benches at the park so easily - hope they all fur over, but to look at her, some may not. In any event, because his personality is so sweet he may not have been abused - b's get pretty angry and stand-offish when people don't treat them right.
@Shaye's:
…In any event, because his personality is so sweet he may not have been abused - b's get pretty angry and stand-offish when people don't treat them right.
True, the fact that he is so good natured is a positive sign… I hope he wasn't abused, but why was he so skinny (how "skinny" is he)??? Bless his heart, he has a good home now and a loving family!!!
I want to thank every one for looking at my post I cant get the pics on this site yet they are saying i need a security token and i need to find out what that is. We thought it might be from a muzzle or sumthin right away but the scar is a perfect circle around his muzzle about the width of a rubber band. It just seems to be too perfect for him to have done it. He doesn't howl at all he just kind of hums and sings under his breath it is the cutest thing ever. My uncle has a basenji and he says Beau looks like he is about 6 months old.
Ok I figured out how to put pics on here they are up now
you could see more of him then you should be able to, but he is already fattening up and isnt showing any signs of food aggression so i think he will be ok.
Wow, that is a Perfect Circle scar on his nose… not sure what it could be from?
It looks like whatever caused it had to have cut quite deep. If only he could talk, there's a story behind every scar!!
That is weird. Hmmm.
Needless to say we might never find out what those marks are, BUT to me they look like they were from a rope around the mouth (to maybe punish or train Beau in some way, what weird way I have no clue) or maybe a gentle leader type harness being too small and it grew into those grooves/scars. He is beautiful regardless, but it does make you wonder, doesn't it?
totally those explanations are all we could think of too, and the scar goes all the way around under the bottom too. It seems to be healed there isn't any redness or anything, I hope it grows some hair back but it really doesn't look like it will. I still think he is the cutest thing ever with it anyhow so if it doesnt bother him it wont bother me lol:).
There you go..
