As I understand it (I've been researching this because I have a deformed kitten prone to pooping complications) mineral oil etc is just fine, as long as used occasionally. It's the active ingredient in Petromalt & various other hairball & constipation meds, it's very effective. Any very high fat diet, or dietary additives (olive oil, fish oil, etc) has the same effect.
Being constipated, blocked. or having chronic diarrhea leaches nutrients & water from the system too....so it's a choice of lesser evils. These conditions will kill a cat or dog quite quickly without intervention.
Long term chronic use of petroleum based products may cause granulomas if not passed with fecal materal. So, mineral oil, vaseline, petromalt etc should probably not be administered for life. But according to everything I have read, these are very effective compounds for immediate use. Especially when the alternative is death, or surgery.
