This is an amazing site to have such thoughtful responses so quickly - thank you.  I have been consulting vets - Shan has now been seen by an emergency room vet (one night when I went into total panic over the very rapid respiration), my regular vet, and her oncologist - so I am definitely not discounting professional consultation and advice.  However, I am thankful to get some other dog pawrent advice/info because nothing my vets have told me or given me has resulted in a happier Shan.  You have each told me something useful - hugapit and joantroj, thank you for your suggestions because my vets have sort of pooh-poohed the notion that Tramadol may be part of the trouble vs. part of the solution, but I live with this girl and I swear her breathing often gets faster after Tramadol rather than more relaxed.  It seems that most dogs tolerate Tramadol well, but I am strongly feeling it is not the drug of choice for Shan. Oncologist did approve taking her off the Tramadol and muscle relaxants so we will see. If nothing else, I want to rule out any drug induced anxiety that may be contributing to the rapid breathing.  Glad to know I am not the only one who might suspect this issue. Jerry - glad to know you have not heard reports of anyone having trouble with Power Mushrooms.  I don't really suspect this supplement (I am taking it myself) but it's the one other new thing in Shan's intake along with prescription drugs/chemo so I just wanted to check.  And, thank you for the info about Tripawds and activity - I really do think this is the crux of the trouble after observing my girl.  I have noticed that at the end of the day, Shan does a little wobble thing in the back end like she's really tired and that is not obvious in the morning.  Her respiratory rate is higher than normal almost all the time now but it definitely does get really rapid in the evening/night.  The onco vet tech told me that she just didn't think that Shan was worn out or straining muscles (I asked cuz my kid's a rowdy girl even at 8 yrs old) even though Shan has made a radical shift in how she does everything because the vet's office only sees that with amputees who are overweight or out of shape.  But that doesn't make sense to me - surely any being that has to so radically change his/her movement could tire faster or have sore muscles!?!  Jerry, I have wondered if I should restrict Shan more.  Onco said he was putting no physical restrictions on her and I have been hesitant to do that because I really want my baby to enjoy herself and she is all about the running around.  Do you think the pain/tiredness is limiting enough to keep the kid from really hurting herself or should I be a little stricter "mommy"?  

I asked the onco yesterday about acupuncture or chiro and he said neither is a problem during chemo so I think that is what I am going to try next.  Seems like either/both may provide some help for either anxiety or pain - most other causes for fast breathing have been ruled out.  There is vet fairly near me that includes those in his practice - difficulty is trying to get appointments and help before I am so challenged with Mom in the hospital next week.  I am also wondering if I should look into PT - it's expensive but available around here so I might see.

At the very least I feel a little better knowing that I'm not crazy and I'm not alone.  In these really scary places in life, it is a real blessing to find community. Thank-you all!

krun15 - thanks for the info! We are about a month out from amp and Shan was weaned off of pain meds initially about 10 days post op.  She had some of the rapid breathing spells post op on meds and off both and onco didn't really take my concerns too seriously.  Then about a week after first chemo, Shan started fast breathing that went for 18 hours and kept escalating.  Couldn't get answer from onco or regular vet and finally 1 AM I took her to emergency hospital because breaths were faster than I could count and I got scared.  E-vet diagnosed back pain from having to adjust her gait, shot her up with muscle relaxers (she could have warned me that she would be sending me home alone with 65 pounds of dead weight of dog to get into the house - what a nightmare!) and prescribed Tram, Rimadyl, and muscle relaxers.  Onco and regular vet OKed next biz day, but I have seen no improvement.  With vet approval, I have stopped pain meds again.  He told me to try Xanax and I saw no improvement with that.  What I have noticed though is although the breathing is still about 50 - 60/min. today, Shan is not as rowdy and is actually sleeping some.  I am wondering if the pain meds were hyping her up and masking the pain enough that she was overdoing it.  At least at this point she does not appear to be in imminent danger and some of my worst fears have been ruled out.  I will definitely check out the rehab ideas (thanks - hadn't found that yet!) and I think I do need to help my girl dial it down a few notches until she has built up the right muscles and the coordination she needs.  I'm not sure what the fast breathing is all about but after reading some of the info here I am more and more suspecting pain due to over exertion and drug induced anxiety.  

Just a quick update to say that Shan is moving slower and breathing better!  Thanks to some nudges from folks here to get me looking in the right direction, I am fairly sure now that Shan was going into some repeated bouts of pain from overexertion after the amputation and reacting to that with highly accelerated breathing/panting.  I can't be sure but I now believe that Shan is one of those who doesn't react well to Tramadol.  (Note to anyone concerned about using Tramadol, I have another dog that has taken the drug long-term for severe arthritis pain and it has been a big help to her so I think it is just an individual thing.) I think the Tramadol was not only exacerbating the rapid breathing, but may have been masking some necessary pain signals to get my little wild one to slow down just a bit after the amp. After several days now drug free, my baby is not racing around any more but sleeping a lot more and her respiration rate is almost back to normal.  Now that I can see her really move without medication mask, it is obvious that she needs some help to build her muscles and coordination to properly compensate for the loss of a front leg. (I admit I am still a bit aggravated that the onco and his vet tech both acted like I was crazy to think my dog may need some help to make the physical adjustment after amputation but maybe you need to live with a Tripawd to really get it.) I have been giving her massages which seem to help, but after looking through the rehab section here on the site I felt sure that I needed some professional PT help and wasn't sure how to get it.  Amazing how lovely things just drop in sometimes - good friend called me and told me about a local PT who did wonders for her dog after the dog had a stroke and I now have an appointment with Angie on Monday.  My Mom is having surgery on Tuesday so this is going to be a bit of a juggling act (did I mention I have a full time job?!?), Shan is holding up her end of the bargain (fighting the cancer while continuing to be my best friend) and her end is way harder than mine, so I'm sure I'll find a way to work in the PT.  In the meantime, what a relief that my girl is now able to rest comfortably and so am I.  I will update info after some PT just in case anyone else ever finds herself struggling to understanding similar symptoms.  

Much thanks to the thoughtful responses that were not only useful but very reassuring. There are some pretty cool people at this site