Hi there,

I happen to be online so ill take a stab

Excessive peeing is called polyuria in vetspeak. It usually goes hand-in-hand w excessive drinking, aka polydipsia (sometimes you'll see shorthand as PU/PD)

Abnormally high sugar levels in the circulating bloodstream can cause PU/PD: the big sugar molecules in the blood are filtered out by the kidneys and pull water with them, resulting in increased urine production. Bc of the increased water loss in the bloodstream, the horse is stimulated to drink more (the polydipsia). That's why you see PU/PD together: its a simple osmotic mechanism that can be caused by any abnormally high substances in the bloodstream (high proteins, etc)

So excessive peeing/polyuria is seen commonly in IR as well as PPID bc of the abnormally high glucose in blood (hyperglycemia). There maybe be other reasons for the PU/PD in Cushings bc of altered hormones, etc, but ill have to let another chime in to clarify

FWIW, one of the first signs that my IR/PPID mare's insulin has spiked (insulin & glucose rise together) is a big jump in her drinking (she lives out so urination is hard to gauge). Ive adapted to using a muck tub filled daily so i can monitor her water consumption very closely.

Hope this helps,
Kerry in NY

So excessive peeing/polyuria is seen commonly in IR as well as PPID bc of the abnormally high glucose in blood (hyperglycemia).

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Horses rarely have high glucose levels. Finger can be pointed at high cortisol levels,though.

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Good point. But how does high cortisol result in PU/PD in IR-only horses (non-PPID)? Transient stress?

I guess b/c i check my mare's glucose & insulin so often (and she has been repeatedly hyperglycemic) that I was inclined to believe hyperglycemia was spurring the PU/PD. I check it with glucometer at draw and then send out G&I on same sample in a serum tube that isnt always spun right away. Subsequent lab results always show a markedly lowered BG from glucometer results in tubes not spun quickly (from known RBC consumption no doubt). I'm wondering if hyperglycemia isnt more common but undocumented in chronic IRs w severe hyperinsulinemia bc of the typical way ambulatory vets draw blood samples: a single serum tube that sits in the car for hours before getting spun. Its just something Ive been pondering bc I have the overlap with handling diabetic dog & cat blood w immed access to glucometers...but of course we're also talking two distinctly different diabetes mellitus: type I and type II...

Furthermore, my mare was diagnosed PPID shortly after the hyperglycemic episodes so i've sorta invalidated my own argument ;) but perhaps its a good experiment for my 8yo IR gelding with normal eACTH and no PPID symptoms

Sincerely,
Kerry in NY
Pinky Sept 2014
Tofurky Nov 2014

Thank you Kerry! That was a great reminder as I should of realized the IR part at least. I know that excessive drinking and urination is something you look for in humans… duh !

I guess I got confused when I saw both PPID and IR. PPID horses have high Cortisol levels so Lorna’s response explains that. (my gelding has/had high glucose). I think my mare holds her urine till she goes into the stall because she likes the shavings and seems she pees more when in heat. My Blaze is doing better these days after starting on pergolide and much of his edema and sheath swelling is gone.

Sharon
E. TN
2005
https://groups.yahoo.com/neo/groups/echistory8/files/Sharon%20and%20BLAZE/