polydipsia/uria beaten me!

Re: polydipsia/uria beaten me!

Kate Richardson — Fri, 12 Dec 2014 16:36:57 GMT

With regards to a DDAVP trial, does anyone know which is the most effective treatment- oral tablets, intra nasal drops or conjunctival drops?

And costs? (cheap/moderate or will cause fainting when mentioned will do!)

Re: polydipsia/uria beaten me!

Andrew Kent — Thu, 11 Dec 2014 19:15:52 GMT

[quote user="Andrew Mellor"]no it remained on 1 drop twice daily. have to admit I have never thought of increasing dose as it has always worked for me before and often only once daily required and presumed it was a fairly empirical dose anyway.[/quote]

People report using up to 4 drops twice (or even three times) daily so it can be worth escalating the dose if no response.

Andy

Re: polydipsia/uria beaten me!

Andrew Mellor — Thu, 11 Dec 2014 18:42:22 GMT

[quote user="Andrew Kent"]

[quote user="Andrew Mellor"]DDAVP instilled into eye twice daily for 31/2 weeks made no difference. forgot that in my last post, where is my brain ![/quote]

I quite like this - gives us more time to get a good discussion going without all the details!

Last question about DDAVP - did you increase the dose over the time period of administration?

[/quote]

no it remained on 1 drop twice daily. have to admit I have never thought of increasing dose as it has always worked for me before and often only once daily required and presumed it was a fairly empirical dose anyway.

Re: polydipsia/uria beaten me!

Anthony Todd — Thu, 11 Dec 2014 18:42:01 GMT

[quote user="Cat Henstridge"]My colleague offered to take the pup on to re-home and when it came in, it came with a big cage and it then transpired the pup had been living in this for 22 hours a day as the owner couldn't cope with it not being toilet trained and pu! The poor little thing was drinking because it didn't have anything else to do! It was re-homed to a good client, treated like a normal dog and has never looked back![/quote]

Yes, but a water deprivation test would have sorted it out wouldn't it?

Sometimes I think these cases need to be kept in away from the owner.....

If it does turn out that the dog's a nutter for water then that's when the boiled water trick might work but it isn't a substitute for more eliminatory trials.

I just wonder if the "licking penis" might be because of a urethral ulcer or similar or the prepuce but I'm sure it's been looked at.

Re: polydipsia/uria beaten me!

Cat Henstridge — Thu, 11 Dec 2014 18:21:28 GMT

A couple of years ago a colleague was dealing with a massively pu/pd Westie puppy. Funds were limited but we did what we could and no cause was found. She got to the stage of ringing referral to see if they would take it on pro bono as an interesting case when the owner decided she couldn't cope and was getting rid.

My colleague offered to take the pup on to re-home and when it came in, it came with a big cage and it then transpired the pup had been living in this for 22 hours a day as the owner couldn't cope with it not being toilet trained and pu! The poor little thing was drinking because it didn't have anything else to do! It was re-homed to a good client, treated like a normal dog and has never looked back!

Re: polydipsia/uria beaten me!

Andrew Kent — Thu, 11 Dec 2014 17:51:00 GMT

[quote user="Andrew Mellor"]DDAVP instilled into eye twice daily for 31/2 weeks made no difference. forgot that in my last post, where is my brain ![/quote]

I quite like this - gives us more time to get a good discussion going without all the details!

Last question about DDAVP - did you increase the dose over the time period of administration?

Re: polydipsia/uria beaten me!

Neil Wheadon — Thu, 11 Dec 2014 17:36:21 GMT

[quote user="Martin Atkinson"]Have I become a dinovet or am I looking at things too simplistically? My definition of psychogenic polydypsia is that for some psychological reason the dog has got it into its head it wants to drink and it has become an obsession.[/quote]

One and the same

Dog drinks too much because it's got it into its head that it needs too, much like a Saturday night out. So in effect a functional lack of ADH

Neil

Re: polydipsia/uria beaten me!

Martin Atkinson — Thu, 11 Dec 2014 16:46:07 GMT

[quote user="Neil Wheadon"]

Psychogenic Polydipsia is defined as a functional lack of ADH due to overhydration and frequently reduced renal concentrating power due to a decrease in medullary hypertonicity from the wash out effects of handling so much fluid.

Central Diabetes Insipideus is where the pituatory is affected (tumours/head trauma or most likely idiopathic) therefore ADH isn't being produced

Nephrogenic diabetes is an inability to respond to ADH regardless as to how much the pituatory is putting ADH into the blood stream

[/quote]Have I become a dinovet or am I looking at things too simplistically? My definition of psychogenic polydypsia is that for some psychological reason the dog has got it into its head it wants to drink and it has become an obsession. Maybe there is a physiological process involving ADH at renal level but this is effect not cause and irrelevant. Simply put: if you drink a lot you're going to piss a lot.

Re: polydipsia/uria beaten me!

Bob Russell — Thu, 11 Dec 2014 15:59:49 GMT

I was caught out nearly 15yrs ago. Spaniel that started to drink bucket loads. Bloods etc completely normal. Actual cause was a faulty bag of food with a higher salt content than normal. Food manufacturer pleaded guilty and paid up for the work done!

Doubt it is relevant to this case but it does happen!

Re: polydipsia/uria beaten me!

Anthony Todd — Thu, 11 Dec 2014 15:46:49 GMT

[quote user="Neil Wheadon"]Is there a 'next' step,[/quote]

Can't be psychogenic as it seems that nothing concentrates the urine and the dog seeks water from any odd source.

Have never heard of "medullary washout" so can't comment.

I wonder if having the dog in for the day just to get the nurses to take it for a walk, make sure it's not getting salt etc. and observe might help. Be funny if the dog was getting something very salty [as others have suggested]...

What can you do if it is nephrogenic?? [I mean other than further diagnosis]

Re: polydipsia/uria beaten me!

Andrew Mellor — Thu, 11 Dec 2014 13:51:35 GMT

SO SORRY THINK I WILL GET MY THYROID CHECKED OR MAYBE I JUST HAVE PRE-CHRISTMAS FATIGUE. IS IT JUST ME OR ARE THERE NOT ENOUGH HOURS IN THE DAY FOR WORK AND ALL THE CHRISTMAS STUFF!

Re: polydipsia/uria beaten me!

Neil Wheadon — Thu, 11 Dec 2014 13:43:49 GMT

[quote user="Andrew Mellor"]DDAVP instilled into eye twice daily for 31/2 weeks made no difference. forgot that in my last post, where is my brain ! [/quote]

It's like a Agatha Christie novel where the author slowly reveals the answer having set the plot. (tried to insert smiley but computer says no)

Neil

Re: polydipsia/uria beaten me!

Andrew Mellor — Thu, 11 Dec 2014 13:39:20 GMT

many thanks for all those responses.

DDAVP instilled into eye twice daily for 31/2 weeks made no difference. forgot that in my last post, where is my brain !

Re: polydipsia/uria beaten me!

Andrew Kent — Thu, 11 Dec 2014 13:33:48 GMT

In this case I would still suggest a trial on DDAVP for a longer period of time before excluding central DI. Nephrogenic is incredibly rare and won't do any harm to use it for a longer period of time.

Otherwise it is basically a diagnosis of exclusion and I am not aware that even a renal biopsy would help unless you could find somebody who would do immuno staining for aquaporins or something....

There are reported treatments for nephrogenic DI - usually thiazide diuretics and dietary modification - I have used these on one cat with good effect but would do the DDAVP trial first.

Andy

Re: polydipsia/uria beaten me!

Neil Wheadon — Thu, 11 Dec 2014 13:25:34 GMT

Thanks to both Andrews

Is there a 'next' step, once you've identified the issue as nephrogenic?

The reference I have talks about renal fibrosis and tubular necrosis and that glorious catch all 'idiopathic due to receptor defect'

If we accept that medullary washout is rare, then aside biopsy, is there a methodology that the average GP (me) would do as the next step to identify a cause as looks like the case here?

Neil

Re: polydipsia/uria beaten me!

Andrew Mellor — Thu, 11 Dec 2014 12:49:28 GMT

This makes sense , I prepared the dog for 7 days prior to actual water deprivation by slowly reducing water intake over those 7 days to twice maintenance then deprivation to 5% body weight loss - no change in specific gravity and ddavp made no difference so in my mind with what has been said before that leads me to nephrogenic DI, but that still doesn't explain the dysuria. sorry perhaps if I had been more thorough in my first post we would have got here quicker. I will tell the owner to use boiled water though and see if that makes any difference.

Re: polydipsia/uria beaten me!

Andrew Kent — Thu, 11 Dec 2014 12:44:10 GMT

It does depend on the way that the water deprivation test is carried out and the chronicity of the disease (i.e. whether there is a medullary washout - which is a slightly controversial topic in its own right). Some people do not believe that medullary washout really exists as it is difficult to replicate experimentally - if it does exist it is likely to be very rare and so not an issue in most cases. The urea may help you here - generally medullary washout is considered unlikely unless the urea is low.

But we shouldn't assume that all dogs with psychogenic polydipsia have washout - most of them don't and so will be essentially a normal kidney and we should therefore expect a normal response.

If you ignore the medullary washout then a deprivation test allows differentiation between psychogenic causes (which will concentrate with water restriction) and DI (which will not). This is complicated if there is an element of washout as it may take longer to concentrate the urine than become dehydrated.

In reality dogs with psychogenic polydipsia rarely get dehydrated during a deprivation test, and if they do it takes a long time. Dogs with DI will dehydrate rapidly (as seems to be the case here).

So this is why most people advise restricting water to twice maintenance for a few days before the deprivation to reduce any potential effects of washout. You should then get concentration if psychogenic and no concentration if DI. The administration of DDAVP (ideally by injection to remove the variability of absorption of the drops) then allows differentiation of central from nephrogenic.

In the absence of restriction beforehand the test can be difficult to interpret because of the possibility of washout.

Hope that makes sense,

Andy

It should look like this:

Re: polydipsia/uria beaten me!

Neil Wheadon — Thu, 11 Dec 2014 12:28:56 GMT

[quote user="Andrew Kent"]Whilst I don't disagree entirely with Anthony's approach - the failure to concentrate during water deprivation essentially excludes a psychogenic cause[/quote]

I'm trying to think this through (physiology)

Diabetes Insipideus is either central or nephrogenic

Looking at the terminology, Andrew is quite right, but further clarification is required

Central Diabetes Insipideus is where the pituatory is affected (tumours/head trauma or most likely idiopathic) therefore ADH isn't being produced

Nephrogenic diabetes is an inability to respond to ADH regardless as to how much the pituatory is putting ADH into the blood stream

Therefore a simple water deprivation test isn't going to differentiate between any of them is it? In the case of a psychogenic cause the kidneys simply hasn't had enough time to replace the solutes in the medulla to allow it to concentrate (so maybe flat water/depriving gently for a few days before the test would be a good idea, to give the kidneys time to correct themselves)

If DDAVP is given this will find the central one, but still won't differentiate between the psychogenic and renal as effectively the same process is occurring in the kidney (an inability to concentrate)

In the dog fails to concentrate after DDAVP and a water deprivation test then either look for nephrogenic causes (scan the kidneys for fibrosis) or in the absence of any other signs of disease, either wait an see or gently deprive water, as with ongoing overhydration the medulla can't recover.

Does that make sense Andrew?

Neil

Re: polydipsia/uria beaten me!

Hannah Wynne Richards — Thu, 11 Dec 2014 11:57:27 GMT

Anthony Todd. I was lucky enough to qualify from Bristol in 1980. The best teacher I ever met (the late Jim Pinsent - who'd spent many years in 1st opinion practice) used to tell us, "Look at the patient".

Wynne

Re: polydipsia/uria beaten me!

Hannah Wynne Richards — Thu, 11 Dec 2014 11:53:47 GMT

Andrew Mellor Dreadful mouths don't get referred, so uni bods probably think they're rare - so don't bother telling students about them!

Cat My approach would be halfway between yours and Anthony Todd's. I would do a pre-anaesthetic panel(especially concerned that the dental probs could be exacerbated by uraemia, and also check felv/fiv. If all ok, would book for a dental,and although I'll probably be shot for this, would also give a long course of antibiotics.

Wynne

PS As to the dog in the original posting - by this stage, I'd be twisting the owners' arms to refer.

Re: polydipsia/uria beaten me!

Anthony Todd — Wed, 10 Dec 2014 23:01:39 GMT

[quote user="Cat Henstridge"]To be fair, with inappetent cats I blame the teeth only if everything else has been ruled out! [/quote]

I think I'd blame everything else only if the teeth had been ruled out....

Don't some vets examine animals any more; this one sounds really obvious!

Re: polydipsia/uria beaten me!

Cat Henstridge — Wed, 10 Dec 2014 21:24:12 GMT

[quote user="Andrew Mellor"]gosh common sense - there doesn't seem to be much of that around any more! going off on a tangent but a locum and new grad ( not sure that's a great combination) had a cat in a few weeks ago that wouldn't eat took bloods for everything under the sun, radiographs , fluids etc etc , he never checked its mouth which was one of the worst I have ever seen all 4 canines loose and abscessed - 3 of which fell out as I examined it ! very quick dental later- nothing left after - and he was happy as a sand boy![/quote]

To be fair, with inappetent cats I blame the teeth only if everything else has been ruled out! Unless they are obviously super sore but I would always do bloods (full if possible) and put them on fluids, I find they are sneaky little buggers when it comes to why they won't eat!

Re: polydipsia/uria beaten me!

Anthony Todd — Wed, 10 Dec 2014 20:30:28 GMT

[quote user="Glenn Hodgson"]diet isn't purely salted ham hughs[/quote]

Yeah, didn't think of a high salt diet...

Re: polydipsia/uria beaten me!

Glenn Hodgson — Wed, 10 Dec 2014 20:25:46 GMT

I would do exactly this. Care di with concurrent washout. Also make sure the diet isn't purely salted ham hughs!

[quote user="Andrew Kent"]

In the absence of finding anything else this is a dog I would probably trial on DDAVP drops at home as the lack of response to the drug at the end of the water deprivation could be due to the medullary washout. So doing a trial for a couple of weeks would allow assessment of response with time to re-establish the medullary gradient.

Andy

[/quote]

Re: polydipsia/uria beaten me!

Anthony Todd — Wed, 10 Dec 2014 12:12:00 GMT

[quote user="Andrew Kent"]Whilst I don't disagree entirely with Anthony's approach - the failure to concentrate during water deprivation essentially excludes a psychogenic cause.[/quote]

I agree totally, just that the boiled water trick is easy to do and "non-invasive"....

A sort of DIY water deprivation test I suppose.