I do not know about Katamine (have not heard of it) but I would think Valium would make the puppies very sleepy and not be able to wake up. The only thing that should be used in a c-section is Isofluraine--- unless it is necessary to protect the mother to use greater measures. If your vet uses anything other than ISO-- ask why and then find another vet!
ketamine is an anesthetic and valium the sedative, ketamine is used more for animals but does get some use in human anesthesia at times too. So with this combo you get anesthesia and analgesia too. I didn't think there was anything wrong with it, it has been used for quite some time I believe.