Yes, the bone possessive issue might have something to do with it. 

But I'll have to disagree with Maxidad, it probably has everything to do with the amputation.   I only say this from experience.  This topic is something that I have dealt with for so long.  It has to do with the fight or flight mentality of being a lame pack animal.   It's about survival while being vulnerable.

I have dealt with it in Comet for 11+ years.  I can count on two hands all the people that has actually touched Comet since I've had her. Even as a puppy, she was this way. She's was born without a functioning front leg. At first I thought it was because she came from a hoarder home and didn't trust anyone but me.  But as I read more about it, I realized it was a combination of both being lame anduntrusting of humans.

Comet won't let anyone touch her unless she has been around you for days on end or unless a vet and or tech appoaches her without fear.  Forget it about dogs, she lunges.  Actually she lunges at people too when we are in public.  It's turned into a bit of a game for her now. 

Comet is one of sweetest dogs, also. She doesn't want to be mean, she's scared.  It's a defensive mechansim. When she trusts and loves, she's all in and will be 100%.  

The only way to combat this is to make her feel secure.  Security is the key.  But even then, it's hard.  You may never be able to have her around other dogs.  Comet had a german shep mix brother for 8 years and even tho he was 3x her size, she kept him on his toes.  She trusted him but his size made her vulnerable.   Our shep mix would actually go to his crate when would leave.  He wanted to be locked up because he was afraid of her.  Their relationship worked great because he was a wuzzy dog and wouldn't hurt anyone.

However, when he died I didn't know how I would deal with her issues.  She has to have a companion dog because she's too scared to be without one but yet she will try to bully them.  So, I got a smaller submissive dog that gave her the size advantage.  Now, I can tell she knows she has the upper hand and doesn't bully anyone.  She's nipped him a couple of times accidently playing and she felt horrible.  She knows she can hurt her new brother because he's small.  

You may have to find something that build Devo's confidence. Perhaps learning new tricks or going into public more. She used to be a friendly dog, so she may come out of it.  I know with Comet, she was terrified to go to Petsmart and it was just easier to not go.  But I have found out that if I take her more, she's not afraid.     

I don't know if I've helped.   The good news, Comet has never bitten anyone.  She's snapped a gazillion times, but never really wanted to bite.   

Good luck,

Comet's mom  

P.S.  Love the name, Devo. I used to listen to Devo all the time in highschool and had an album. 

Magic has always liked other dogs, and was somewhat insulted when we would walk ( prior to amp) and we would meet a dog aggressive one that the owner said could not meet.  (Echo was dog aggressive and could only be with the wolf/wolfdog pack he had grown up with) He does however have a really really bad habit that comes out in the spring and is a dominance move and when we had two wds, it was a power play and toward the end of Echo's life, Magic really pushed it (I think HE knew Echo had the tumor even if stupid mom had no clue).  He does the stupid dominance humping (he has been neutered since about 11 or 12 weeks.. Echo was done at about 8 weeks) and when we saw Ruthie at the park I was so embarrassed that he wouldn't quit it.  He was doing it to pits he met...the only thing that seems to confuse him into not even trying is if there are more than just one dog and he can't get one to stand still.  It isn't sexual (he also did it to OJ)...

I noticed a definite personality change in Magic after the amp but while he was on tramadol and didn't make the connection until after I had pulled and tugged my poor body into pain.  Magic has never really liked strange men (okay no jokes about aren't all men strange...I'll behave) UNLESS they have a dog on a leash...then they are ok.  He will never like my son.  But he practices avoidance and I have never forced him to meet or let someone pet him.

I am assuming Devo is not on any medication since the amp was long ago....well I guess I wasn't any help at all, was I!!!!

HEY WYATT...tell your youngster of a mother to google album (snicker)

LOL @ Maxidad!  So which category to you put yourself in - old or middle age!  I'd like to think I'm middle age, but the more I see my friends retire and the more I consider it myself, I guess that places me more in the 'old' category!  Thanks for the big dose of reality!

And, btw, I take exception to you speaking of our Max as an obnoxious mutt.  How could that sweet face and those gorgeous eyes be an obnoxious mutt? 

Thanks for the giggle this morning!

I, too take exception to Maxidad...

First, disparaging poor Max's name !! 

Second, he called us 40 something's "OLD" !!  Hey, I'm not old!  (Thanks to my Botox and Restylane injections!)

Third, the fact he had money to purchase CD's !!  Weren't they like $12 dollars when they came out? 

Some of us only had cassettes and still do (somewhere).  And if the player mucked the tape, you got your handy dandy cassette tool out (ink pen or #2 pencil) and rewound it!  You had to pause your singing for a moment through the crinkled garbled part!!

Spirit Jerry, I've seen a pic of your mom striking a pose with Aqua Net big hair and blood red lipstick WHILE HOLDING A BEER!  Hmmmmmm.