Linda,
I've used Petzlife on 4 of mine and haven't had the loose stools. Which kind did you use, (Salmon or regular) was it the spray or gel, and how many days have they been off it? I agree about taking the stool samples in to the vet, maybe it is a coincidence and something else is going on. If you only gave it to Moose ( April sends kisses, by the way
), one time, it seems unlikely that he should have the loose stools for that long? Hope you get this figured out.
ps, I love your new avatar!!!