Polydipsia/Polyuria

[J-Lu]

Hello,

Does anyone have a horse diagnosed with polydipsia? My horse really never urinated under saddle until the last couple of years. Recently, he’s lost weight (could be attributed to drought and grass quality) and occasionally, but not regularly, frequently urinates under saddle. Last week, he urinated 5 times…Once long, the other 4 times short. Clear urine, says my friend the livestock vet who collected some. We thought he was drinking a ton of water but recently it was found that his trough had a leak. A chem and electrolyte screen came back negative except for unusually low blood glucose (hexokinase). Kidney and liver function are fine.

He’s in regular work (around our heat dome and rainy weather) and acts just fine under saddle. The vet who pulled the blood thinks his polydipsia might be behavioral.

Has anyone experienced this?

[quietann]

Test for PPID (Cushings). Frequent urination and weight loss are classic signs, especially in an older horse.

[Paint_Party]

Was going to make the same suggestion: Test for Cushings even if there are no other apparent outward symptoms. In fact, while you’re at it, just do a full metabolic panel if not done yet.

Although an acquaintance of mine in the barn bought a very nice show horse gelding that came with a peeing issue. Every time he’s brought out to ride in the arena, he’ll pee. Apparently he’s done it for years, yet he doesn’t do it at shows. The lady’s husband is a vet and ran all kinds of bloodwork for the PPE, and everything came back normal. So it’s just a weird behavioral thing the horse does.

[J-Lu]

Thanks
@quietann and @Paint_Party!

I think he’s peed multiple times in a ride maybe 3 or 4 times this year but not any of the other times I’ve ridden him or had him out. And we’ve done some LONG rides this year with friends at a horse facility nearby.
He’s 15 and and is only on a small scoop of balancer (half of what the bag recommends, I weighed everything but my vet thinks the bags oversell what horses actually need). We’ve added some regular grain to this for now.

I’ll talk to my vet friend and “real vet” about a Cushings test. My “real” vet was not concerned with his weight loss at spring shots/dental. My vet friend seems less concerned about Cushings right now and literally sees him all the time. She still thinks his drinking is behavioral because he hasn’t urinated under saddle since I’ve ridden him since. She pulled two RTT of blood, there may be serum in the freezer that can be sent and I can provide dry ice and a shipping container. I’ll talk to her when I next see her.

Yes, @Paint_Party, behavioral polydipsia seems to be a real thing in horses and my vet friend has seen it alot.

Thanks!

[BayMoose]

You need plasma for ACTH unfortunately.

I agree with above, testing for PPID is where I would start. Have you been able to determine how much he is actually drinking a day?

[J-Lu]

Not recently. His trough had a leak and he’s had a new pasture mate as of about 2-3 months ago. My vet friend threw out the idea of withholding water/looking at urine, but his kidney function seems fine on the last test.

[Montanas_Girl]

@J-Lu

half of what the bag recommends, I weighed everything but my vet thinks the bags oversell what horses actually need

Actually, the feeding recommendations most feed companies (with one notable exception who shall remain unnamed) put on the bag will provide your horse with the minimum NRC requirements for amino acids, vitamins, and minerals assuming the horse is eating 1.5-2% of its body weight in average quality forage daily. You cannot know whether more or less will meet your horse’s minimum requirements without testing your forage. And there are many cases where “optimum” is probably higher than “minimum” - Se being one example.

[Ghazzu]

@J-Lu

A chem and electrolyte screen came back negative except for unusually low blood glucose (hexokinase)

Don’t know where the hexokinase comes in–never seen it on a cham panel–but if there was a lag between when the blood was drawn and when it was spn down for plasma separation, the RBCs will continue to consume it, giving you a lower reading.

[Texarkana]

My horse’s water intake and urination decreased to normal levels with a low dose of pergolide, so seconding (thirding?) the suggestion to explore Cushings.

[Marla_000]

You may want to test for Insulin
Resistance also. some studies have connected polyd/polyu to
A couple types of diabetes.

[J-Lu]

Thanks, everyone! I appreciate everyone’s suggestions!

@Ghazzu, that makes a lot of sense and is likely what happened. Thanks for chiming in!
Michigan State did the panel.

@Montanas_Girl, thanks for correcting us. He gets Purina Enrich Balancer and should get 1.5-2.5 lbs/day according to the label. I’ll weigh it out again this weekend. Years ago I had the pasture formally analyzed for nutrient content and calculated his diet. I might do that again since he’s now in the next pasture over and I’m sure the forage quality is pretty different now than 5 or so years ago.

[IPEsq]

Would the excessive urination cause more glucose to be excreted potentially?

Also agreeing to test the horse for PPID and EMS.

[Ghazzu]

Glucosuria occurs when the blood levels are so high that the kidneys are unable to reabsorb all of it.
So you only see it when the blood glucose is high over a relatively long period of time.
(Cats will sometimes have a stress hyperglycemia simply from an office visit, and the quick way to differentiate it from true hyperglycemia is to check the urine. If negative, it’s not considered pathological.)

[ladipus]

Kidney disease, Cushing’s/PPI ID, and IR are the first things that come to mind whenever I see a horse that is polyuric/polydypsic

[J-Lu]

Thank you! The blood tests ruled out kidney disease. We could do a urine concentration test but he’s been acting so normal lately. We (my vet friend and I) took our horses out to a Horse Park for a good 4 hours on Sat. He urinated once, defecated twice. And not even in the trailer on the way home! She thinks any polydipsia is behavioral because the polyuria is so rare with him. We’ve been watching him closely for the last month or two. He doesn’t really fit the bill of a horse with systemic or organ disease, according to her. She sees the horse daily and one of her horses is pastured with my horse.

I’ll loop in my regular vet with the results. Thank you!