I'm guessing his seizures have started somewhat recently? In the past year or less?
With what you describe, I am inclined to say that your dog has either a brain tumor or serious structural brain disease. The symptoms you describe go along with this diagnosis. Of course, without seeing your dog, it's hard to say 100%, but in general, late onset seizures coupled with a head tilt, and circling behavior is pretty indicative of this problem.
I think that when it comes to deciding when it is time to euthanize, you have to consider quality of life. Think of the top 3 things that bring a wag to your dog's tail. You know, those things that you know the dog absolutely loves to do. This could be eating, a walk, meeting you at the door, playing with a ball, etc. Old age robs our pets of many of these things, but disease takes them away completely. When 2 out of the 3 are gone, and there is no joy on a daily basis, it is probably time to let go.
Spend some time with your pup in the next day or so, and put yourself in his place. Would you want to stay, or be released? Often owners keep dogs around because it is hard to let go. In hind sight they question if they waited too long. I believe that either way you will question your decision, because this is a tough decision to make.
You know your dog the best. Look in those puppy dog eyes and see if he is still "there". He'll tell you when it's time.
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Dog Veterinarian
20 years experience in veterinary field.
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