The Recommended Approach to the Coughing Dog with a Murmur - Brought to you by Boehringer Ingelheim 

It can take a while for side effects to wear off. But you know your pet best and it's hard to see them uncomfortable/sick after they react to a new medicine. You could ask your vet for a different cough reliever or even a short term one, if possible, when it gets bad. Then You can always try another vet and explain everything you went through and how sick your pet was on the previous medication, if no help from your own vet. My own pet is on cardisure and was given a new heart meds that made her sick. When I rang saying I'd to stop it, I was told "but she's only on a very small dose". How this response addressed my pet being sick and my report of it had me bewildered. As if the small dose could not have made her sick. The 2½mg of Fortekor put her in a heavy sleep with odd limb spasms, twitching, panting, nightmares, vocal dreams and disorientation after waking and lethargic for rest of the day. I couldn't do this to her anymore after 3 days. I really hope you get your pet relief for their cough. Side effects are uncommon (my pets never has reactions until this one). And medications can make their lives comfortable and more bearable living with sicknessl so I really hope your beloved pet finds relief soon.

Gabapentin affects their kidneys and isn't safe long term - Dr Google. Lots of meds come with down sides. Dr Andrew Jones ( Veterinary Secrets) has some great alternatives

I'm in the same boat with my chihuahua - she's had a cough and mucus for 2 years now, and the vet hasn't really done much for that. In fact at first they treated me like I was making it up. Earlier this year she was diagnosed with an enlarged heart. She was put on Enalapril but that made her cough so bad I had to take her off it after just 2 days. It also gave her a distended stomach, which she did not have before. When I spoke to one of the vet's on the phone after this, all I got was "I'm so sorry" and regarding the distended stomach she said "it's her cancer". What? No one ever told me she had cancer. To my knowledge, she has not even been tested/examined for cancer. ??? So I have been researching and trying supplements and better foods for her. These have helped a little with the coughing and reverse sneezing and mucus. She still has them but they are not as bad or as frequent. But the heart thing is definitely getting worse. So I thought I would give the main vet one more try. I called them Thursday to try and get an appointment. Only to be told he did not have any openings. He was booked for the foreseeable. Would I like to see another vet. I said no. The one wrote my dog off like she was already dead, and the other went ahead and gave her a vaccine after I said NO! My dog does not do well with vaccines - they have nearly killed her several times and each time I have managed to nurse her back to health - usually by using puppy replacer milk because she couldn't keep anything in for a while and was off her food. You have no idea how furious I was with that vet when she grabbed my dog's nose and squirted the vax up her nose, saying she had to have it. YEs but NOT on the same day as the other vax she had already been given. I do note that this was not too long before she got sick with the coughing and mucus. Anyway, I said the main vet could call me back. I expected the call Friday. He never called. A lot of Vets seem to have become like Drs... uncaring and untrustworthy. I guess we are on our own and I will continue to try things to see what helps. Last week I added turnips, basil and kelp to her diet. They seem to have helped with the mucus a bit for a few days anyway. She is still eating and running when she wants to, so that seems to be good, right? However she is carrying a bit too much weight and it is hard to get her to lose some. I'm not giving her a whole lot to eat as it is, so really don't feel comfortable cutting her back any more. More research ahead I guess. I am following Dr Judy Morgan on here and several others that give more holistic options. She also has recipes if you want to home cook for your dog. I did try home cooking, too, but my girl started piling on the lbs!!! She loved it, mind! My girl is now on CoQ10 and just started Taurine, she's also taking several other supplements and herbs for the heart, like hawthorn and red clover, and slippery elm & marshmallow for the cough. Dosages can be found in various videos on here. You might also look for acupressure for dogs, where you gently message specific points to help with various conditions. Wishing you luck in finding something that helps your dog.

DONT DO THE GABAPENTIN…they sent my chi home with that the other day and it almost killed him…now I don’t trust a word he says. Trust your gut! Try HAWTHORN, dandelion ,FISH OILS(make sure they are clean tho) or high quality olive oil, decent amount of taurine, high doses of co q 10 or ubiquenol(broken down form), feed chi tonic foods like squash, pumpkin,sweet potatoes,carrots, and for grains oats and millet,egg yolks are blood cleansers…plenty of earthing/grounding!!!