dehydrated but still drinking excessively

[irish heights]

Hi can anyone offer me any advice, I have an 11 year old warmblood mare, she has being excessivley drinking, and not eating her hard feed but eating small amounts of hay this has being going on now for 6 days, she had blood test last thursday and yesterday both showed she has PCV level of 40 and raised protien, she is getting very tired, my vet is getting back to me in the morning but was wondering if any one has experience of this situation.
Thanks

 

[TheBlack]

Insulin resistant? I know a horse who drank loads and it turned out to be this http://www.naturalmatters.net/article-view.asp?article=2097

 

[Shay]

Does sound like insulin resistance or cushings. What does the vet say?

 

[GreedyGuts]

Has your vet collected a urine sample? This would enable him/her to get an overview of her kidney function. If she is drinking excessively but is continuing to lose fluid because her kidneys cannot concentrate her urine, ruling out renal impairment would be high on my list.
Hope you've managed to get some answers in the meantime.