Have had great success with Vetasyl. My cat had constipation problems but this supplement has worked wonders. I would definitely recommend this.
I've now used this for my two cats for hairballs and for two of my three dogs for constipation (for my GS) and just to promote regularity in my older dog. In all cases this worked really well. Hairballs are way down and constipation cleared up nicely.
Ordered this product online after ordering it from vet for several months for my aging cat. It is exactly the same and saved me dollars plus was delivered to my door. I would recommend this to anyone whose animal needs a little extra fiber. There''s nothing crankier than a constipated kitty!