Tricky PU/PD case

Re: Tricky PU/PD case

Anthony Todd — Sun, 19 Jan 2014 18:25:18 GMT

[quote user="GrooveJet"]My case was significantly PU/PD[/quote]

Suitably chastened with no room to be snide, a smartarse or even funny; I live and learn, still.

Re: Tricky PU/PD case

Miriam Lodewyks — Sun, 19 Jan 2014 18:06:15 GMT

My case was significantly PU/PD, SG below 1.010, intermittently inappetent and lost a little weight, but haematology, biochem, electrolytes, ACTH stim, T4 and UCCR repeatedly normal. Diagnosis finally made when sudden onset hyphema resulted in enucleation and histo confirmed lymphoma. All in all a somewhat unusual case.

Re: Tricky PU/PD case

Anthony Todd — Sun, 19 Jan 2014 13:38:23 GMT

[quote user="Robin Grimmer"]Good job they didn't give it your steroid cocktail - as that could have screwed up both the diagnosis and the treatment.[/quote]

Too true, even I and the dynamic duo would have hesitated, hopefully..

Still surprised your case was so apparently normal.

Re: Tricky PU/PD case

Robin Grimmer — Sun, 19 Jan 2014 13:28:56 GMT

[quote user="Anthony Todd"]

[quote user="GrooveJet"]Anthony, I can't decide whether you're trying to be snide, or funny. Either way, nobody likes a smart-arse, no matter how hilarious.

[/quote]

Sorry, if you're referring to the lurcher, it was a genuine question, I think, not snide, or trying to be funny and I'm certainly not smart enough to be a "smartarse"; "arse" probably.

Was it a totally normal dog with just PU/PD?

[/quote]

Actually a lot of dogs with lymphoma can seem otherwise well on initial presentation. And if there was hypercalcaemia, then pu/pd might be the major presenting sign. Sure, once you've got ginormous lymph nodes everywhere it's fairly obvious - but I'm assuming the OP and subsequent poster would not have missed that. Good job they didn't give it your steroid cocktail - as that could have screwed up both the diagnosis and the treatment.

Re: Tricky PU/PD case

Anthony Todd — Sun, 19 Jan 2014 12:45:09 GMT

[quote user="GrooveJet"]Anthony, I can't decide whether you're trying to be snide, or funny. Either way, nobody likes a smart-arse, no matter how hilarious.

[/quote]

Sorry, if you're referring to the lurcher, it was a genuine question, I think, not snide, or trying to be funny and I'm certainly not smart enough to be a "smartarse"; "arse" probably.

Was it a totally normal dog with just PU/PD?

Re: Tricky PU/PD case

Miriam Lodewyks — Sun, 19 Jan 2014 08:42:23 GMT

Anthony, I can't decide whether you're trying to be snide, or funny. Either way, nobody likes a smart-arse, no matter how hilarious.

Re: Tricky PU/PD case

Anthony Todd — Sat, 18 Jan 2014 23:27:37 GMT

[quote user="GrooveJet"]FYI: 9yo lurcher that presented with similar symptoms to the ones described in the OP, has just be diagnosed with multicentric lymphoma. I had a feeling something else was going on, now I know what. :-(

[/quote]

What no weight loss, appetite loss, change in activity, pale membranes, enlarged lymph nodes, abdominal lumps, leaping about, happy?

Just drinking a lot and peeing a lot, yeah, I'd have missed that I reckon.

Re: Tricky PU/PD case

Miriam Lodewyks — Sat, 18 Jan 2014 20:01:37 GMT

FYI: 9yo lurcher that presented with similar symptoms to the ones described in the OP, has just be diagnosed with multicentric lymphoma. I had a feeling something else was going on, now I know what. :-(

Re: Tricky PU/PD case

Anthony Todd — Sat, 18 Jan 2014 11:53:27 GMT

[quote user="Sarah Keir"]I have it on good authority that it still is standard treatment in some areas, and woe betide the new graduate who doesn't. ;-)[/quote]

[tongue in cheek but joking on the square]

And I'll wager, remarkably effective, cheapish, and client satisfaction is enormous, they were very successful!

Probably just as "effective" in the case under discussion and economically in the right hemisphere.

I remember T & H's admonishment; "say something, do something.give something", to which I add, give an injection!!

These days it's "do nothing until the test results come in" and, if the diagnosis and treatment is not on the form, do a cat scan, Xray ultrasound or refer to a specialist.

And whatever you do don't do anything until you have a diagnosis.....

Re: Tricky PU/PD case

Sarah Keir — Sat, 18 Jan 2014 11:21:35 GMT

[quote user="Anthony Todd"]

Well I was a Bets man for years and, back in the day, B12 and Bets was the standard treatment

[/quote]

I have it on good authority that it still is standard treatment in some areas, and woe betide the new graduate who doesn't. ;-)

Re: Tricky PU/PD case

John Flynn — Fri, 17 Jan 2014 22:42:05 GMT

[quote user="Anthony Todd"]Glad to see there's another steroidophile to help in the crusade for patient relief [we could start a charity][/quote]

Make it a "Trust" and I'll enlist some other board members:

My good mate 'Thyroid'-Ted, who believes thyroid hormones to be the single greatest weapon against all things illness related in dogs, there's no epidemic of obesity as his clinic ;-) Why bother testing for hypothyroidism when euthyroid dogs can benefit just as much from supplementation

And his counter-part, 'Anabolic-Andy', who can improve your management plan for all poorly thriving patients just by the addition of his own brand of steroid - watch fractures heal and appetites improve - win the tour de France...

Re: Tricky PU/PD case

Anthony Todd — Fri, 17 Jan 2014 22:20:24 GMT

doubled up, sorry

Re: Tricky PU/PD case

Anthony Todd — Fri, 17 Jan 2014 22:16:33 GMT

[quote user="John Flynn"]I'm a pred man at heart and go on the premise that dex is about 7 times as potent as pred, so work out my dex dose based on that; the labelled vet-preps have wildy differing doses.[/quote]

Well I was a Bets man for years and, back in the day, B12 and Bets was the standard treatment among the vet plebs for virtually anything not a cat bite or kennel cough. In fact two prominent north London vets used to do a song and dance called "B12 and Bets"- hilarious!

Again, back in the day if you didn't give an injection then the animal wasn't treated at all and if you had to send of a test this was only because you didn't know what was wrong and were therefore totally incompetent.

I had a lovely London locum, super guy adored by the clients who was wont to diagnose emphatically, "a touch of distemper"....

Re: Tricky PU/PD case

John Flynn — Fri, 17 Jan 2014 21:30:46 GMT

[quote user="Rory Bell"]Glucocorticoids interfere with the action of ADH on its recceptors in the renal tubule[/quote]

But why so much polyuria in dogs as opposed to humans (where PUPD doesn't seem to be a common sign of cushings for instance? http://www.nhs.uk/Conditions/Cushings-syndrome/Pages/Symptoms.aspx) or cats (I often give cats steroids and don't get complaints re PUPD from owners?) I guess it's just part of that individual variation with dogs getting more intereference at ADH receptors than other species and, as you say, different glucocorticoids can interfere there to differing degrees.

Re: Tricky PU/PD case

Rory Bell — Fri, 17 Jan 2014 21:24:01 GMT

[quote user="John Flynn"]

[quote user="Rory Bell"][I'm Irish, I don't play cricket] :-)[/quote]

In spite of the fact I've never met an Irishman that does play cricket, we've managed to cobble a team together on a few occasions. Occasionally they even win a game... http://www.dailymail.co.uk/sport/cricket/article-1362262/CRICKET-WORLD-CUP-2011-Ireland-beat-England-OBrien-smashes-fastest-ton.html

how embarrassing

[/quote]

And suddenly, just like that, cricket was a national sport!

Fair play!

Re: Tricky PU/PD case

Rory Bell — Fri, 17 Jan 2014 21:20:17 GMT

Apologies John and Anthony, missed your last posts....and trying to combine making dinner with this thread and like a typical male, am not succeeding at multitasking.

Glucocorticoids interfere with the action of ADH on its recceptors in the renal tubule. The extent to which different steroid preparations cause PU/PD will vary depending on the individual and the preparation; those that have a pure glucocorticoid activity will exert their 'PU/PD effect' through inactivation of the ADH receptor, those that have a mixed glucocorticoid / mineralocorticoid activity will exert their effects via blockade of the ADH receptors in the renal tubules and also via expanding circulating volume which in turn will increase renal blood flow. The extent to which these varying influences exert a clinical effect is also down to the individual and their disease processes (which is a cop out I know, but nonetheless probably true)

cheers!

Re: Tricky PU/PD case

John Flynn — Fri, 17 Jan 2014 21:17:55 GMT

[quote user="Rory Bell"][I'm Irish, I don't play cricket] :-)[/quote]

how embarrassing

Re: Tricky PU/PD case

John Flynn — Fri, 17 Jan 2014 21:11:27 GMT

[quote user="Anthony Todd"]75% ish or less of the normal dexameth.[/quote]

Depends what you call a "normal" dexamethasone dose ;-)

I'm a pred man at heart and go on the premise that dex is about 7 times as potent as pred, so work out my dex dose based on that; the labelled vet-preps have wildy differing doses.

Of course I'm sure that dex being 7 x potency of pred is based on humans and may not ring true for dogs obviously.

[All that said, I remember seeing a guide dog with presumed mild atopy when working up in UK not that many years ago that was inconveniently PUPD on preds or medrone even at low doses, but fine on quite high depomedrone doses; this was all fine, with a depo- or two a year, for about 6 years until GDBA decided that it need treated - queue allergey testing, atopica which made the dog vomit etc etc... when I suggested that the dog hadn't been that bad to start with and did fine with the occasional depo injection i was advised that GDBA would not allow a working dog to get repeated steroids like this I asked them for evidence that longterm steroid use was any more detrimental than long-term atopica (a known carcinogen) use as it clearly hadn't been out long enough that anyone could have done any serious longterm studies such as life expectancy on it... they hadn't and as far as I know still haven't...]

Re: Tricky PU/PD case

Rory Bell — Fri, 17 Jan 2014 21:06:22 GMT

Hi Anthony

I agree with your last post:

Psychogenic polydipsia is a central nervous disorder of dogs characterized by polydipsia (≥ 100 ml/kg/day).

yes, its is....in fact possibly the only canine condition characterised by primary rather then compensatory polydipsia....so.....

Affected dogs often compulsively search for water and have clinically measurable hyponatremia.......

or, more accurately, measurable borderline or actual hypo-osmolality (see my post at 18.42 on thursday).....

[which should be easy to measure].......

it is indeed.....

Diagnosis is one of exclusion, with blood tests and a modified water deprivation test used to eliminate other differential diagnoses, particularly central diabetes insipidus.......

agreed, but see my post today at 14:46 at later this afternoon for an explanation why a WDT not be preferable to a DDAVP trial. I appreciate the debate though, and I'm not really trying to convince anyone....just presenting some info to allow folk to make up their own minds!

[I know they won the ashes so they deserve some credit]

[I'm Irish, I don't play cricket] :-)

Re: Tricky PU/PD case

Anthony Todd — Fri, 17 Jan 2014 21:02:08 GMT

[quote user="John Flynn"]Why do glucocorticoids cause polyuria in dogs?[/quote]

Yes,I've always wondered that, and told westie owners, somewhat lamely, [cos they're the prime culprit, even at correct doses of dexamethasone] that it was most unusual......

Some dogs do wet the bed after steroids and they're not normally incontinent.

Some male westies used to just stand in the street and the urine just poured out, no leg cocking etc. at all. I seem to remember giving westies 75% ish or less of the normal dexameth. dose in case of this.

Re: Tricky PU/PD case

John Flynn — Fri, 17 Jan 2014 20:51:02 GMT

I've just come in to page 3 of this, but very interesting! A couple of, probably dumb, questions that I'm not embarrassed to ask: Does it matter whether the PUPD is the result of undiagnosed cushings which is subtle enough not to find marked blood changes or the result of central diabetes insipidus? If it responds to DDAVP (and stops wetting in house as a result of the PUPD) does it matter to whether this is secondary NDI or CDI? Why do glucocorticoids cause polyuria in dogs? Why do some glucocorticoids (e.g. methylprednisolone) seem to cause less polyuria than other (e.g. prednisolone)?

Re: Tricky PU/PD case

Anthony Todd — Fri, 17 Jan 2014 20:43:09 GMT

There's this:

Psychogenic polydipsia is a central nervous disorder of dogs characterized by polydipsia (≥ 100 ml/kg/day).

Affected dogs often compulsively search for water and have clinically measurable hyponatremia.

[which should be easy to measure, by the way]

and this

Diagnosis is one of exclusion, with blood tests and a modified water deprivation test used to eliminate other differential diagnoses, particularly central diabetes insipidus

from this:

http://www.vetbook.org/wiki/dog/index.php/Psychogenic_polydipsia

[They won the ashes so they deserve some credit]

All I'm suggesting, as I've said, is to limit the water intake for 12 hours to boiled water only, as the first test, not after all the others, 'cos I, found it worked in a number of dogs. If it didn't or they got ill I looked further.

Even if all you do is make boiled water the only water available, in a normal dog with no other signs, illness or abnormality, sometimes, actually often, water consumption goes back to normal and I've always called them psychogenic polydipsic.

Sounds as if I missed making a load of wonga with all those expensive tests and procedures....

I'll get my coat.

Re: Tricky PU/PD case

Anthony Todd — Fri, 17 Jan 2014 20:22:37 GMT

[quote user="Rory Bell"] Of course you might restrict a dog's water intake, and if that dog has CDI or NDI you might get away with it without close monitoring. My point is, you might not.[/quote]

I really would be surprised if any "normal" dog [apart from it's PD/PU] would be at any risk at all if it's water intake was limited for 12 hours, if it were then I've been very lucky on a number of occasions.

Re: Tricky PU/PD case

Rory Bell — Fri, 17 Jan 2014 18:28:46 GMT

I think that the problems lie in restricting water intake are mainly concerned with a dog who is drinking more water then usual in order to mantain homeostasis (i.e a dog that has a compensatory polydipsia). These dogs will have an ongoing loss of free water due to absolute lack of (CDI) or lack of activity of (NDI) ADH. If they don't take on extra free water to compensate for free water loss, they will suffer from hypertonic dehydration. This means that extracellular Na concentrations progressively increase due to free water deficit. These dogs will not have classic signs of dehydration because extracellular volume is maintained. Their body weight will decrease which is why 3-5% loss of body weight is taken as the end point of the WDT rather than 3-5% dehydration as assessed on a clinical exam.

The problem with an uncontrolled increase in circulating Na is that intracranial volume decreases with resulting intracranial haemorrhage. Hypertonic dehydration is also difficult to correct (the patient with CDI or NDI is conditioned to lose free water, which marked replacing free water deficits challenging, and overly rapid correction of hypernatremia can cause more neurological problems. There is absolutely no way of telling how quickly a patient with NDI or CDI will suffer these consequences following any degree of water restriction without closely monitoring them.......and hey presto we're back to doing a full on WDT.

I'm sorry if this sound like I'm belabouring a point. Of course you might restrict a dog's water intake, and if that dog has CDI or NDI you might get away with it without close monitoring. My point is, you might not.

cheers

Re: Tricky PU/PD case

Anthony Todd — Fri, 17 Jan 2014 17:00:44 GMT

[quote user="Thomas Johnson"]But if the dog is polyuric its water intake is going to be more than the physiological requirments of a healthy dog, so you are depriving it of water, it's SG won't increase and you will dehydrate it.[/quote]

Yeah, even I get that but, as the SG hasn't increased it may give some of the posters a nudge to investigate further, rather than the other way round...you're only doing it for 12 hours, it's not going to suffer too much, and it may not, actually, be dehydrating at all.

You could do a PCV to be sure, I think. if you want.

Remember this is a "normal" dog drinking and peeing a lot, no other signs or problems, except a bit senile.