Best enema liquid for IMPACTED stool?

Need suggestions on what others found to work best on softening hard, IMPACTED stool. Tried several things after MUCH reading. This goes beyond normal constipation.

Cat has CKD & the vet wouldn't let me increase his sub-q fluids & blew off my concern about cat not passing feces daily - on the same food as before he was diagnosed.
My fault for listening to him. He's gets 100ml / D of lactated ringer's solution, plus wet food (not holding it down well since constipated). If he doesn't drink enough extra on his own, I syringe some w/ low amts of added electrolytes.

Now, I can feel the fecal mass in his colon (he doesn't complain of me palpating it). Basically, impacted. He can pass watery stool around the mass (getting Miralax + probiotics + digestive enzymes), but if it has much solids / fiber, it flattens as it goes around the mass. Not good.

The "experts" say miralax & other osmotic laxatives - lactulose (stool softeners) don't work on already hard stool. They can get too big to pass, even if soften them up, unless you / a vet then breaks it up manually.

I gave a child's glycerin (only) rectal suppository - it produced a BM, but didn't move the mass - another indication it's probably too big / hard.
Gave another one next day - very small BM. I guess what was able to pass, did so the 1st time.

Then gave an isotonic electrolyte solution enema ~ 35 - 40 ml, based on vet manuals' guidelines to soften the mass. He didn't even pass the water - maybe a little over night. He either absorbed it (which is OK), or it went into stool. Not enough to soften the mass near his rectum.

Next day, gave a normal saline 0.9% NaCl enema - 35 ml. Added some ducosate sodium (stool softener often used in enemas, even made for pets). It's not "supposed" to cause bowel movement - just soften stool, but I think it affected him some. This time, he couldn't hold all the water as long as he needs to help soften it - but held some.
But the mass felt a bit smaller after than before the last enema.

I've heard of it taking multiple enemas - in animals or humans - to soften impacted stool. I've read about adding things or medications to enema, to improve water penetration into hard, dry stool. Supposedly, because they're hard & usually have fat content, they resist water. But, I'm not sure what works best - still cat safe. Or just nice warm water?
An isotonic saline or electrolyte solution for base water is probably best for CKD cat, so doesn't get electrolytes out of balance.

Thanks.

Are you in the vet or medical industry? You sound way calmer than I did when my cat was constipated, and it was not nearly this bad.

Miralax can take a few days for sure, not sure how long your kitty's been on that. Lactulose or Laxatone can be used also, but it sounds like enema might be the way to go. I haven't actually given one before. Does your vet have any input on this, or have you not discussed it since the last visit? It sounds like you may have lost your confidence a bit in that vet. Perhaps call the ER vet and talk to them? I found the one I called rather helpful when Sara had a UTI/cystitis flareup. Some may say bring her in but others will talk to you on the phone depending on what it is.

I'm on a CKD group on FB with someone who is a bit more versed in enemas than I am. But I'm sure there are some folks here that have had CKD cats that have needed enemas. At least I know there are quite a few folks here with CKD kitties besides me.

It is true that Miralax takes a few days to work effectively, BUT, once the impaction is there, miralax is pretty useless.  Sometimes an impaction needs to removed by a Vet because nothing else will work   I'm guessing this requires sedation, and there ARE certain sedations that are semi-safe for kidney cats.  I say semi-safe because with everything there is always a risk.  (I just had my healthy cat have a dental and I was still  nervous...possibly because I recently lost my 16 year old kidney cat)

Anyway, I can see why your Vet doesn't really want to increase his sub-q fluids from 100 ml a day.  It's a balancing act on those fluids, that's for sure.  Yes, they need hydration, but all that fluid can have adverse effects on some of their organs (heart/lungs) as I found out with my previous kidney cat .

What I did with my last two kidney cats was to KEEP them on a regimen of Miralax twice daily, every day to keep them regular.  If I skipped just one "treatment", I would know because I would start to see them strain in the box.  Of course, this does not help you until you get that impaction out.  You're sure it's stool and not a blockage? 

You sound extremely knowledgeable about what you are doing, and said you've read a lot about it, but just in case, here is my go to for all things kidney cat:  http://www.felinecrf.org/constipation.htm#miralax_mechanism

Thank you all. FWIW, y'day the vet didn't find any impaction - least in lower colon/ rectum - either palpating outside, or digital exam.
Doesn't mean couldn't be one somewhere in GI tract.

That's the good news. Bad - apparently has quite enlarged prostate. Per vet, that's what I was feeling & he felt on exam.
Same issue - as far as squeezing feces by, flattening it.

He said weren't any meds approved for cats - or generally used off label - to shrink prostate. IS THAT THE UNDERSTANDING OF OTHERS w/ cats & enlarged prostates?
He gave a v. short supply of Finasteride 1 mg, take 1/2 tab daily. Called it off-off label for cats - there were "no meds typically prescribed for feline enlarged prostate".
I find that hard to believe. I think I'll start a new thread on this - get way too long, complicated for most folks & me.

I've never heard of a neutered cat having an enlarged prostate, but perhaps I was going off a bad assumption. Is your kitty neutered?

Would it be OK to take up the prostate & nausea issues in the new thread?
http://www.thecatsite.com/t/320292/...d-prostate-natural-or-prescription-treatments