Help! My Dog has an Unknown Neurological(?) Condition

Concern: Full body muscle spasms and cramping, and other scary things

Breed: Dog, American Bulldog/Bully breed

Weight: 50 lbs

Age: ~7 years old

Sex: intact male

Location: Central CA, US

History: I found him as an emaciated stray roughly 2 months ago. From the start I have had the intention of rehoming him, but it seems that when one of his health conditions ends, another begins, so here we are. I love him so much already, and he is probably one of the most angelic and wonderful dogs I have ever met, but I can't keep him because he wants to hunt and kill my cat (more on that later). Everyone has their flaws, I guess. Anyways, when I found him, he had a full body skin and ear bacterial and yeast infection and was very underweight, but otherwise appeared healthy. I had concerns about possible hip dysplasia, due to an unsteady and delayed gait in his back legs. An x-ray two weeks after I got him showed healthy hips and lower back, but spondylosis between just two vertebrae in mid/low back region. He has since been fully treated for his skin/ear condition and is at a healthy weight, but his gait in his back legs did not improve. He seemed to have skin allergies and mild GI upset, so I transitioned him to a limited ingredient dry food and his allergies went away. About 1.5 weeks ago, he attacked my cat and in order to get him to release her, we had to take extreme measures (AKA hit him on the head). We tried everything else before resorting to that, including pouring water on his head, sticking a finger up his butthole (I heard somewhere this worked, but it didn't work on him), and pulling his testicles with force. Once none of that worked, out of fear that the cat was dying (she is okay now), we just started hitting him on the head and he finally let go. I took him to the vet that day because I knew he'd have a headache after that, and they prescribed 100mg carprofen (once daily), 300 mg gabapentin (2-3 pills twice daily), and 100 mg trazodone (twice daily) all for pain and anxiety. The trazodone was my request, since he has shown separation anxiety from the start and he could no longer sleep in his crate in my room now that the cat needed to recover there in peace. I knew he wouldn't be happy about sleeping in his crate in the living room, hence the traz.

Start of symptoms: began 48 hours ago

I gave him 600 mg gabapentin and 100 mg trazodone that night, per the vet's directions. Come morning, he seemed a bit wobbly and tense, but I expected that. I attributed the wobbliness to the meds and the tension to him being old and just having been beat up by us the day before. That morning I gave him 100 mg carprofen, and that night I gave him the same gabapentin/ trazodone cocktail. Next morning, he walked rigidly, almost limping on one paw. I gave him a carprofen with breakfast to ease the pain. I inspected his paws and legs and watched him closely throughout the day, and what was weird is that he would wince when using his front left leg, but he didn't try to avoid using it. Rather, his body would cramp, curving his spine in a slight C shape towards his painful foot everytime that paw touched the ground. Still, I thought the best way to help him was with the medication. I gave him that same gab/traz cocktail that night again, and the next day he could hardly walk. I fed him and gave him 100 mg carprofen, thinking he must've hurt himself somehow or his spondylosis was flaring up from all the stress with the cat and a new sleeping arrangement. He was tremoring a little bit too. It looked like his back was in pain because he'd get up and try to walk, or walk just a few steps, and then immediately sit down or lay down. All the while, he did not want to lift his head. A couple hours into the day, noticing that he was not getting better AT ALL and seeing that he was not just shivering, he was spasming, I stopped all medication immediately. It took 24 hours for him to return back to normal. Once it was all out of his system, he no longer limped or showed any sign of pain or cramping. I couldn't imagine which of the three medications caused this reaction, and after talking to two vets who both invalidated this experience, saying none of those medications cause anything like that, I just took it upon myself to research it. Although its rare, all three medications *can* cause severe neurological damage. Usually not when given in the correct dosages, though, and he certainly did not take more than prescribed. I knew that when the time was right, I'd have to introduce one medication at a time to see what caused that reaction.

Fast forward to two days ago, and a week from the last time he had any medication. I notice around 8pm that he is acting a little anxious and uncomfortable. He is usually very calm and sleeps a lot, always looking very comfortable, but he was getting up like every 15 minutes and reposition himself on his bed. Looking back on the day, I realized that while his temperament was good, starting that morning he would anytime he wanted to look up at me, he would sit down first. He wouldn't raise his head enough to look at me while standing. I thought maybe his back was hurting a little and so I didn't play with him that night so he could rest. Once he started acting restless, I knew he was in more pain than he was in this morning, despite not having done anything particularly strenuous. I thought to myself that it might be a good time to try the carprofen again, since that seemed to be the least likely culprit of his negative side effects to his med cocktail. I gave him 100 mg carprofen with dinner, and sure enough, his tremors came back -- worse this time. At that moment, I realized that it WAS the carprofen that caused his neurological adverse reaction, and I was glad that I could give him gabapentin to ease his back pain, feeling sure that I had solved the medication mystery the hard way. I gave him 600 mg of gabapentin and he just got worse. and worse. and worse. Every neurogical adverse reaction he had a week prior to his medication, he was now having 3x. All of his muscles were spasming, particularly near his shoulder blades. He couldn't walk more than a few steps, and he would take very small steps at that. He wouldn't raise his head. He would eat or drink or go to the bathroom. He kept wimpering to go outside, but for some reason couldn't actually pee or poo, so hed shuffle back inside and lay back down for an hour and try again. Eventually he just collapsed to the ground and just started peeing himself. Hours later, what was yesterday morning, he went outside to poo and he actually was able to stand long enough to do it. He was wobbley, but he did well. His bowel movement was normal. Afterwards, he just layed down in the freezing wet grass, refusing to get up to go inside -- even though he was shaking. It took a lot of time and coaxing, and eventually he did get inside, but I can only imagine how much pain he must have been after forcing himself to stand that long to poo. Every couple hours, I noticed that he was able to stand for longer and longer when he needed to, although he never seemed more willing as the time passed. I interpreted that as him being in some kind of severe pain and the medication making it worse. As the medication wore off, he improved but his baseline was bad. At 4 the same day, I took him to the vet. They didn't believe me that his medication was causing neurological adverse effects and during the vet's physical exam of his spine, he didn't find any sign of severe back pain -- even though his entire body was still involuntarily spasming like crazy and he wont stay standing up or look at the new stranger's entering the room and slamming the doors. The vet says he might have a muscle strain. I didn't see how a muscle strain cause symptoms this severe so I asked if he thought it could be IVDD. He said he can't speak to that because they don't have an MRI. He brushed me off every time I brought up that he seems to be having a neurological issue. Then he said that if I really think that, then he needs to see a neurologist (which, I technically agree with, but he was saying it in a way to get me to stop bothering him). He gave him a shot a buprenoraphine (which did not help his pain nor his spasms) and he did blood work. He said everything was within normal range, but his hematocrit levels were trending downards and same with his protein levels. Not enough to cause major concerns, though. I had to ask him to prescribe a muscle relaxer (DUH!), which apparently didn't seem to occur to him before I mentioned it, but he did prescribe it after I asked -- 500mg methocarbamol (3 times daily). Once we got home and the buprenoraphine wore off (8 hours later), I gave him the muscles relaxer. That was 3 am this morning. I was so hopeful because the buprenoraphine seemed to make him feel and act worse, not even affecting his muscle spasms, and I thought the muscle relaxer would be a game changer. It wasn't. He is still spasming, albeit, maybe the slightest bit less intensely as before the muscle relaxant. But the intense spasms still happen in waves. After his first dose of the muscle relaxant wore off, and none of the other medications were in his system anymore, he actually went outside and full emptied his bladder standing him, leg lifted. That was such a relief. He went inside and layed down, on his side, and he finally took food from my hand and allowed me to squirt water into his mouth. He even seemed happy for a second and wagged his tail when I pulled out some freeze dried salmon treats. He never lifted his head, though. And the spasming returned and his walking looks so so painful. Even his eyes look wide and scared because the muscles in his face are pulling him every which way. Every once in a while his ear will get stuck in a cramp and ill massage it back into place. But his whole body is throbbing and spasming and cramping and aching and tense. It is so terrible.

I know that is SUCH a long description, but it all feels important. Thank you thank you thank you to anyone who has any advice or suggestions!