I can kind of relate to the problems that you are having. Well, not me personally, but my parents.

Their dog Jake is an angel at the vets, he loves going, even if he is being examined or having shots or when he was neutered. He's a greyhound GSD mix.

But he is absolute freaky about toenail trims, he has tried to bite my parents before. They tried to muzzle him and do it at home, still didn't work.

Now, once a month, they have to give him two tranquilizers an hour before they go to the vet, muzzle him, and have the vet trim his nails. Then they take him home and let him sleep off the tranquilizers. Not that they want to do all this mind you, but this is the best way they've been able to handle it so far. And it's only been the past 4 months, and he's 3 years old. I guess one day he just decided to hate nail trims.

I hope you find a solution to your problems. Hugs to you and Logan!