My Lucy has LP in both knees - but we keep her weight in check; give her some joint supplements and try to prevent her jumping TOO much. (It's hard to completely stop it because she is very active).
She had a couple of episodes where she would just sink to the ground during or after a walk. The ER vet diagnosed her with LP but my regular vet said LP should not cause her to sink to the ground and not be able to move. He did more testing to rule out other issues. Of course, we already knew about her liver issues so all that was factored in.
These episodes only happened two times, and that was last year; but it WAS scary.
If your pup is having continuing problems and has to scoot across the floor; I would not stop at where you are now because that does sound very serious. I would agree that a specialist opinion is in order if your dog is not back to regular walking.
Best of luck.
__________________  Mommy to Lucy, Ringo, and Matthew |