Matt, I have been told not to use petroleum jelly as it is OIL based and this could cause problems if residue was left on the area after it was tucked back inside. I have been told that Water based lubricants like KY and Saline would be much better to be used as not to leave oils inside their rectum, if it happened to be a rectal prolapse.
As the resident forum Vet, whats you say on this. I would love to hear.
(Ill next be able to return replies early next week.)