Well, it seems I was worried for nothing.  She woke up about 30 minutes ago, got up to drink water and follow my husband around until she saw I was cooking their dinner.  She stood by the kitchen waiting anxiously, and hopped quickly to her bowl as I went to dish it out.  She gobbled everything down, including the extra cup I added at the end and licked the bowl clean.  

I think the 300mg of gaba may be a bit much.  She's 50 lbs.  Has anyone else had similar issues? 

I spoke with the surgery unit earlier today, and they said we could start weaning her off the pain meds after day 7.  I think I'll try cutting the gaba back to 200 for a couple days...then down to 100 if all goes well.  I'm slowly reincorporating her full spectrum CBD in her meals, so I'm hoping we can wean off the gaba and the carprofen over the course of 5 days and return her to purely full-spectrum CBD for pain management , with Arnica at the ready in case she needs quick pain relief. 

Would greatly appreciate any experiences/insights anyone has to offer. And thank you very much for such an incredible wealth of information and support.  This website has been a Godsend to me. Bless everyone who takes the time to share and support.

Thank you very much for the response and the reassurance.  I look forward to learning more from Jerry as well.

Thank you for the reply, Jerry.  

She is on Sentessa Advanced Care, 30mg twice a day, and yes, her vet is aware.  Thanks for the insight on the combination of CBD and gaba. The vet did not mention anything about that.  He did have me take her off her golden paste 7 days prior to her amputation surgery until 10 days post-surgery.  He also had me take her off fish/omega 3s 3 days prior to the surgery, but he said she could return to those at any time afterwards.  I just returned her to sardines as an incentive to eat with her morning meds this morning.  Interestingly enough, he did not restrict her CBD/hemp extract while she's on the gaba.  

As an update to her condition, she's doing wonderfully today. She's more alert today than any since surgery.  She's even back to wagging her tail when she sees us coming or we talk to her.  She went outside with me while I poop scooped (we have 3 dogs total), enjoyed sniffing around the yard in the sun, peed and even pooped.  It looked very healthy and twice the size of her normal piles.  

So today we're feeling particularly blessed/fortunate.  It gives me hope that we have days ahead with her of tail wags and relaxing walks through the woods.  At this point, I don't need to know how many, just that they're still ahead of us. 

Thanks again for all of the information!

Thank you for all the responses and support.  They were all extremely helpful.  

As an update, Galaxy is doing amazing!  As so many on this site say over and over, the resilience of dogs is just incredible.  We call her our brave girl every day.  In case this is helpful to others who are about to or are already going through this, here's a summary of our experience from our journal.  Let me start by saying that she had not walked on that leg for nearly 2 months prior to the amputation, so as our VetTech reminds us, she had already largely adapted to being a defacto Tripawd by the time of her amputation.  So her movements starting day 2 post-op may not be typical for a dog who has not already been learning how to live on 3 legs.

Days 1 - 5:  She slept probably close to 20 hours a day, especially at first.  Thankfully her appetite was decent, and would get up several times a day/night to drink some water.  I took her food to her the first 2 days and hand fed her to relieve her of the need to move around in order to get sustenance.  The carprofen and gabbapentin made her extremely woozy for the first 10 hours after taking it.  So she did not like moving around.  She would stumble at times, which scared her, and so she'd return to her crate where she felt safest.   Initially she would go outside once a day to pee, but by day 4 she was peeing twice a day.  She did not poop until day 5.  After that she would poop once a day.  

Days 6-10:  Her appetite was slightly depressed some days/meals; others she would do well.  She continued to drink when thirsty (5-8 times a day) and would pee a couple times a day, poop once a day.  We took the advice of using a t-shirt to keep her from her staples.  We kept a BarkBay halter on her, which was soft and covered around her chest, neck and back behind her front legs.  I'd stick her back leg through one of the t-shirt arm holes, then roll that sleeve up so that it wasn't hanging down and interfering with her knee/movements.  On her back, I safety pinned the other arm sleeve so that it kept the shirt snug along her underbelly.  Her tail stuck through the neck hole.  I tucked the bottom of the t-shirt up through/around the halter on her shoulders and safety pinned each side so as to keep it snug and not draping under her belly.  When she wanted to go outside, we'd remove those 2 safety pins, drop it down her back leg, and she'd hop out of the sleeve and outside to potty.  When she came in, I'd take a warm damp wash cloth and make sure her incision and behind were clean.  She patiently let me do it all and put her "dress" back on her.  

Regarding pain meds, her carprofen ended day 7, but her gabapentin continued to day 14.  She weighs ~50 lbs.  I slowly stepped her down from 300 mg gaba every 12 hours  through day 8 to 200 through days 10-12, and then days 13-14 to 100.  At the same time, she started getting her Sentesa Advanced Care CBD ramped back up from 30 mg once a day (days 10-12) to twice a day (days 13-14).  The problem we found with her with gabapentin was that it made her severely agitated for about 3-4 hours after taking it.  About 30-45 min after taking it she would begin whining, then pacing between spots, trying to lay down, but popping back up 1-3 min later.  At some point she would just stand next to me and whine.  So I would give her a long massage, and within 15 minutes she would be relaxed and sleepy.  This happened every time she got gabapentin, and when I mentioned it to our VetTech, she said she'd had similar reports from patients.  So it doesn't appear to be all that rare.  Given she'd had an entire limb surgically removed, I couldn't imagine the pain she must be in, so we continued to give it to her.  I just lost a lot of sleep the first 10 days post-amp because inevitably either the gabapentin agitation would start at bedtime or else she'd wake me up in the middle of the night to need to go outside to potty...and wanted a massage or to lay next to me until she fell back asleep.  We logged a lot of massages just to help reduce the anxiety the first 7-10 days post-amp.  

Days 11-15:  I felt a substantial amount of relief by day 11. As I'd ramped down her gabapentin, she began to seem more like herself.  Rather than being a wobbly zombie (most of her waking time days 1-7), by days 8+ as she would get 7-8 hours post gabapentin, she would begin to become more alert, wobble less, and wag her tail when she saw us and we talked to her.  Those tail wags were hugely reassuring that she was going to be Galaxy again once we got through the worst of the recuperation.  Days 11-15 she was alert probably 8 hours or so out of 24, mostly 30-45 minutes or so at a time, and then she'd snooze for another hour or so.  She started to indicate she wanted to go on walks or take car rides because she'd try to get out the garage door when we had put our shoes on.  That was hugely reassuring, and I did take her for a few short car rides between days 8 and 12 so that she could enjoy some time "out."  Days 12+ we started taking her on short walks in the woods (10 min or less).  Day15 when she got her staples out, she was walking all over the neighborhood park, sniffing everything and enjoying lots of attention from strangers.  It was so obvious how much getting out for a little bit to smell smells brightened her mood.  I also noticed that by day 10 or so, if she stumbled or fell, she no longer got scared and ran to her crate to hide.  Instead, she'd begun to take it all in stride.  She rights herself and keeps on keeping on. 

Our VetTech also taught us a number of exercises to have her practice daily to help her build her core strength and her muscles she now relies so heavily on.  She adores the VeTech visits and the treats she gets whenever she does her exercises.  Similar to the walks, her exercises perk her up mentally, as well as help physically.  And of course, she still loves her massages.  

Most amazing of all is that to all of our surprise, starting on Day 15 she began hopping up on our sofa and loveseat again.  She backs up, takes a couple running "hops" and then leaps right up on the furniture. Then she steadies herself as she tries to find the exact spot she wants...and then lays down, sighs, and sleeps up there just like she used to before she became lame.  Absolutely amazing to watch.  One of many instances where she demonstrates just how resilient dogs really are.  

I can't say yet how effective this is, but for anti-cancer protocol she rotates through several different supplements, in addition to her plant-based diet.  Golden paste, pumpkin, berries, mushrooms, lots of cruciferous vegetables and legumes are standard meal fare, and she gets sardines 4-6 times a week. Her appetite has returned in full force, and I've started making her high protein/extra fat treats to help her build/maintain her muscle mass.  She'd gotten a little thinner there for a bit, but she's beginning to slowly build back her muscles.  We plan to start her again on hydrotherapy in the next month to help with strength.  

Her doctor did ask us to occasionally (once a week), when she's resting, count her breaths when she's relaxed.  They should be roughly 20 or so per minute.  When we begin to see a consistent uptick and it gets to normally around 30+ breaths per minute, that may be the first sign of lung metastases.  At that point, we may want to take her in to get x-rayed to confirm...or just continue to give her the best palliative care possible. 

So that's where Galaxy is now.  She's breathing roughly 18 breaths per minute when relaxed. She's happy and seems to be pain free for the first time in nearly 3 months.  She's eating well, barking at the birds again in the sky (she's part Greyhound), and yipping at me when I don't feed her fast enough.  She may be hopping around on 3 legs, but she seems to have adjusted just fine.  And we are just thrilled with her recovery. 

Thank you all for this wonderful site and for all of supportive posts.  I've read hundreds of posts on this site, and they've reassured us every step of the way.  I hope our posts about Galaxy are somehow helpful to others who may need that reassurance as well.

Jerry and Benny55, you are both Rock Stars!  Your never ending support to those families in need here is just awe inspiring.  It restores our faith in our fellow humans.  Bless you all for all of this!  What a wonderful thing heartfelt grass roots small movements can be...and how very powerful when they snowball with the support of those who care.  

I will try to load a photo or two this evening...or this weekend.  I love seeing the pictures of the other dogs, so I should share Galaxy's as well.