Hi, we went through seizures with Zoe, our yellow lab which started out like vestibular disease. We elected not go pursue further diagnostics as she was 14 but after several months she started to seize and her decline was rapid as the seizures became more frequent and we assumed a tumor. We did not use pb but I think titration is important so perhaps a slight decrease in dose by your vet could help. We also had hard stool at the very end of our time with Amy our black lab. Geriatric pups are hard because it means time is moving on. We were very careful to watch and listen as we were supportive of the 'I'd rather be a day early rather than a day late'. All 3 left us last year and we've entered the young dog world again. Best of luck with Ruger.