I have used it but it depends on the circumstances,I always speak with my vet first and then we go from there.
Last whelping we had contractions were not effective at all had a pup in the canal way to long and could not get him out,I ended up calling a wonderful lady who has been breeding for 30+ years (I could not get my vet) she advised me to give a shot I did and out he poped but he did not make it,I was worried she was going to be so swelled after me trying to get him out etc that the next pup would have problems she adivsed to give another shot after 1 hour if no progress,well no progress and another shot and out popped the last pup.
Her and I have spoke after and she did not think the calsorb would of worked in this situation? I spoke with my vet also and he thought the same thing.
My vet is ALWAYS around but had a family emergency that night.
I did call another vet and he said she would be fine sometimes they can be in the canal a hour
And told me to wait 24hrs for the next pup
SO I more less just hung up.
My vet also said sometimes both would be needed depending on symptoms. CAlsorb and oxy
I have alitter due here this month and told him no family emergencies
He laughed and said I will try Tammy