Heart murmur?

    Welcome to the forum;  You need to convince your grandmother to let you take him to the vet again; there's a very good possibility that the vet could prescribe or recommend a medicine that would help him. Also, a vet cannot euthanize a pet without the owner's consent, so she wouldn't have to worry about that. We had to have our 18 year old cat euthanized a few years ago after a lengthy battle with kidney failure and even though Ralph was so sick he couldn't even stand up, I had to sign a consent form for him to be euthanized. The vet had been treating him for this condition for 2 years and agreed it was finally time to let him go, ( he had done pretty well except for the last few months) but the consent form is required to prevent malpractice suits. Good luck; I hope you can convince her that seeing the vet is the best thing for him.[]

Heart murmurs can be treated -- please convince Gram to let you take this dog to the vet.  Frankly this is NOT THAT OLD!!  An 18-19 year old poodle is 'older' -- but not at that age.  In this day and age MUCH is treatable that wouldn't have been earlier and a lot of animals live with heart murmurs. 
 
They probably should have his teeth cleaned as well -- that has a lot to do with keeping the heart healthy. 
 
They are not going to confiscate a dog and euthanize it -- it just plain can't be done.  They may ultimately suggest it, but that would be a decision your grandmother should make on her own ... not be forced into it.  AND if the vet has done this sort of thing before then GO TO A DIFFERENT VET if she's uncomfortable. 
 
Tell her to be prepared to spend a bit of money -- on a dog that old you should do a senior blood panel (which will be about $100 or so and is a broad range blood test to give them a good idea of the dog's health) and as I said, the teeth need to be cleaned (and you don't need to necessarily completely sedate an animal to do their teeth).  But you can do a lot for a senior animal with a well-done blood panel and scaling the teeth!

My 12 year old schnauzer has had a heart murmur since she was 4 years old without any problems and without any treatment.  I'm taking her to a cardiologist next month to stage her disease & decide if she needs medication.  One of the signs of needing treatment is coughing.  Sometimes medication can be used before complications to prevent them, that's why I'm taking her in.

The heart has little valves that open & close to let blood go through it.  When you hear a murmur, what you're hearing is the blood flow backing up at a valve for some reason.  If the blood flow backs up for a long period, fluid accumulates and causes coughing.  People live with heart murmurs for a long time, so can dogs.  Laying on the floor to prevent coughing is a serious sign that the dog needs treatment.

Maybe you or your brother can take the dog to the vet for your grandmother.

Sorry for the really long delay.
I've tried to convince her to take the dog to the vet. She ultimately thinks that, even if the vet doesn't put him to sleep, they'll have to operate on him (i.e. sedate him somehow).
Is there any medicine that can control this coughing?

Thanks again.

Heart surgery isn't going to happen for a heart murmur.  The vets don't usually want to use anesthesia on a dog with bad heart disease.  They treat with medicine to help the heart pump better and to relieve the fluid collection which leads to the cough. 

There are no over the counter medicines to treat this, this needs to be managed by a vet.