Nephrolithiasis in a 7yr old cat

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Wed, 06 May 2020 11:02:51 GMT

[quote userid="11308" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222312"]

Human paper. Again. It being given to rats is to check toxic doses rather than to see if it works in them.

Anecdotal stories of ingestion of owners meds are from a toxic point of view and unwanted side effects, not the drug doing it's actual job.

[/quote]

Gee if it was possible to misconstrue a post.....

*Nothing to do with effect, just to say if it was non-toxic for rats [at a calculated dose-rate] it is likely to be SAFE in cats at the same calculated dose-rate.....

*And, you got it half-right, it was just to show that it is UNLIKELY to be toxic in cats, even in possibly high doses.

RE: Nephrolithiasis in a 7yr old cat

Anthony Dennison — Wed, 06 May 2020 10:33:30 GMT

Human paper. Again. It being given to rats is to check toxic doses rather than to see if it works in them.

Anecdotal stories of ingestion of owners meds are from a toxic point of view and unwanted side effects, not the drug doing it's actual job.

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Wed, 06 May 2020 10:20:51 GMT

https://dx.doi.org/10.5213%2Finj.2012.16.1.13

Tamsulosin has been used in rats [700gm], experimentally , and there are lots of anecdotes of cats' possible ingestion of their owners Tamsulosin capsules, although uncertain evidence of ingestion but it probably isn't that toxic.

Hope this isn't just deleted?

RE: Nephrolithiasis in a 7yr old cat

Beats — Wed, 06 May 2020 09:54:18 GMT

I've researched this a little more and it is difficult to see where the 0.005mg/kg tamsulosin dose comes from in the cat. I've traced it back thus far only as far as 2014 where it appeared as follows:

"Prazosin(Minipress;Pfizer) Alphaadrenergicantagonist Inhibitsα1adrenergicreceptors Functionalurethralobstruction. Alsoureteralobstruction 0.25–1mg/catPOq8–12h Sedation, hypotension

Tamsulosin(Flomax;BoehringerIngelheim) AlphaadrenergicantagonistInhibitsα-1adrenergicreceptors Functionalurethralobstruction .Alsoureteralobstruction Dosesareanecdotal:0.004–0.006mg/kgPOq24hSedation,hypotension"" [Journal of Feline Medicine and Surgery(2014) 16, 579–598]

But this is from a review article on urine marking and included for completeness only and is highly unlikely the author had ever used it. So use of tamsulosin in cats must date from before 2014 (probably well-before?). It has never become popular as an alternative to prazosin, one could only speculate on the reasons, but at the currently suggested doses, with the availability of 0.4mg tablets/capsules (some sustained-release) I suspect that the available formulation and suggested dosing are probably the most obvious reasons. A few anecdotal reports of ingestion of owner tablets appear to suggest that the safety-margin in cats is reasonable and it may be that the dosing suggested is too conservative and it may outperform prazosin at a higher dose than that suggested in the cat without incurring more hypotension and other deleterious effects, but this would be pure speculation. Such speculation has been put to test to a very limited degree in the dog, but not in the cat to my knowledge in published work (either not been done, or was no better / worse than prazosin and thus not published).

Other alpha-1 antagonists available in UK which I find no mention of even anecdotal use in cats are:

doxazosin (smallest tablet size 1mg)

terazosin (smallest tablet size 1mg)

alfuzosin (smallest tablet size 2.5mg)

I can see no reason to favour any of these over prazosin in the cat based on complete lack of published experience of their use, however it is again possible that any of them could out-perform prazosin in the cat. Given the marked interspecies differences in pharmacology, one could only speculate.

So from that list, it would appear that tamsulosin is the best current contender for a second-choice alpha-1-antagonist in the cat after prazosin based on at least a suggested dose rate, however this likely involves considerable faff in dosing to split accurately based on the suggested dose rate?

I am always on the look out for a back-up second-choice to prazosin (lest it be discontinued, although I suspect a compounded version would be available anyway), but have never found one, so would be interested to hear of what others consider the second-choice alpha-1 antagonist in cats to be for urethral relaxation. I have never run out of prazosin, so have never needed to look at a second-choice alpha-1 antagonist, but presumably that is the scenario in which one might try tamsulosin?

My experience suggests that keeping prazosin on your clinic's "don't run out of this drug list" (say a 6 month supply in stock) has avoided the need to resort to more experimental drug alternatives.

RE: Nephrolithiasis in a 7yr old cat

Beats — Wed, 06 May 2020 07:26:16 GMT

[quote userid="5904" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222293"]Tamsulosin appears to be the No 1 drug for urethral obstruction/dilatation/relaxation in men yet hasn't been even tried once in the only animal that has a really common problem with that syndrome [male cats] [/quote]

Tamsulosin is an alpha-1 antagonist, like prazosin, however more selective than the latter in humans for alpha-1a receptors and thus less unwanted cardiovascular effects.

Prazosin is commonly used as urethral relaxant in cats, with a good safety margin, years of clinical experience, convenient tablet sizes (can give half or full 1mg tablet 2-3 times daily). It may or may not also be of some help as a ureteral relaxant in the cat.

Tamsulosin dose suggested in cats is 0.005mg/kg which is impractical.

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Tue, 05 May 2020 17:35:25 GMT

[quote userid="11308" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222289"]Sigh. Just read part of my post and not the other part Tony, plus all the specialists contributing to the subject. Just because you think it's a good idea, doesn't mean it should be used. [/quote]

Nah, I said "TRIED", there is a difference!! [sigh]. Viagra [in case the chemical name has eluded you], does leap into my mind. It's classic support for my repeated argument!

Tamsulosin appears to be the No 1 drug for urethral obstruction/dilatation/relaxation in men yet hasn't been even tried once in the only animal that has a really common problem with that syndrome [male cats] and I get slammed for thinking it might be worth a trial, even infused into the urethra near the obstruction.....!!

Go figure!

Surely minds even slightly greater than mine can see it's worth a try......

RE: Nephrolithiasis in a 7yr old cat

Anthony Dennison — Tue, 05 May 2020 15:52:27 GMT

[quote userid="5904" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222280"]I do wonder then why none of these were suggested in my, or fellow sufferers personal incidents and Tamulosin was immediately prescribed almost flippantly and with a smile and worked so well and immediately [almost].[/quote]

Sigh. Just read part of my post and not the other part Tony, plus all the specialists contributing to the subject. Just because you think it's a good idea, doesn't mean it should be used.

I think I should get paid a million pounds a year and get to eat ice cream hourly. Not going to happen.

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Tue, 05 May 2020 10:04:54 GMT

[quote userid="11308" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222276"]

Prazoscin

Diazepam

Coccygeal epidurals

sub-ureteral bypass devices (SUB)

[/quote]

I do wonder then why none of these were suggested in my, or fellow sufferers personal incidents and Tamulosin was immediately prescribed almost flippantly and with a smile and worked so well and immediately [almost].

Surely some vet must have actually tried it, even locally. It seems such an obvious drug to try!

But it's vet dogma now, so that's it!

PS if you click on the numbers or the red text in Wikipedia you get straight to the reference, which are mainly scientific journals; saves so much time!

RE: Nephrolithiasis in a 7yr old cat

Anthony Dennison — Tue, 05 May 2020 08:14:47 GMT

[quote userid="5904" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222263"]Sorry, I've been out of it for a while[/quote]

Yes. Yet you still turbo-post with your opinion on what must be given despite having limited knowledge of current treatments. Perhaps when multiple Diploma holding specialists suggest multiple other options except yours, it might be that it just isn't used because it doesn't work

[quote userid="5904" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222263"]what's the medication that works?[/quote]

Prazoscin

Diazepam

Coccygeal epidurals

sub-ureteral bypass devices (SUB)

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Mon, 04 May 2020 14:15:16 GMT

[quote userid="11308" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222262"], and we have medication that works? [/quote]

Sorry, I've been out of it for a while, what's the medication that works?

RE: Nephrolithiasis in a 7yr old cat

Anthony Dennison — Mon, 04 May 2020 13:44:18 GMT

[quote userid="5904" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222259"]

Sorry to flog a dead horse but I'd just like someone actually to try it in a blocked cat.

Wouldn't be the first time a drug turned out to have an unrelated practical benefit.

[/quote]

Why, when it is unlicensed, untested, and we have medication that works? Is it ethical to trial a medication with unknown efficacy instead of using the recognised treatment in an urgent clinical scenario such as a blocked cat?

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Mon, 04 May 2020 12:14:28 GMT

[quote userid="3318" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222016"]ReTamsulosin - I have used in dogs with reflex dyssynergia - it is probably more specific for the canine alpha-1 receptors but not likely to be more useful than prazosin in cats in my opinion. [/quote]

Sorry to flog a dead horse but I'd just like someone actually to try it in a blocked cat.

Wouldn't be the first time a drug turned out to have an unrelated practical benefit.

[much to the delight of elderly gentlemen, who assumed they we in a cardiac drug trial.....]

RE: Nephrolithiasis in a 7yr old cat

gerard mclauchlan — Thu, 23 Apr 2020 14:48:21 GMT

Hi Anthony

The pain is generally associated with the hydronephrosi/hydroureter. I had a kidney stone myself and no clinical signs until it blocked my ureter - it always amazes me how some cats show such limited evidence of pain. Kidney stones themselves are rarely painful and the recommendation is not to touch a non obstructive nephrolith in dogs and cats (nephrotomy to remove a stone can result in 20% reduction in GFR).

Ureteral dilation is best treated by a SUB in cats and stents in dogs. Stents can be placed cystoscopically in dogs and are much better tolerated. In cats ureteral stents are associated with high rates of dysuria (35%) and encrustation (20%).

ReTamsulosin - I have used in dogs with reflex dyssynergia - it is probably more specific for the canine alpha-1 receptors but not likely to be more useful than prazosin in cats in my opinion.

Hope that helps

Gerard

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Thu, 23 Apr 2020 11:47:04 GMT

[quote userid="8569" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/222003"]I’ve suggested that we take another look with the scanner next week![/quote]

"kidney stones" are supposed to be one of the most painful condition in humans. Are they painful in cats? Certainly urethral blocks are!

I suppose one could argue that if the stone was stuck in the ureter [or the urethra] then dilation should release it, a la stent?

And [one last try] tamsulosin is the drug of choice in humans with few failures, if any, and "mechanical" removal is only still practiced in Australia, AFAIK....

If I was a cat I think I'd rather be given a pill than have a fairly major op!?

RE: Nephrolithiasis in a 7yr old cat

Tom Ward — Thu, 23 Apr 2020 09:29:02 GMT

Thanks Roger, it’s a tough old case, trying to gauge opinion on whether watching is ok. Working out how much of an issue this little stone is is obviously not straightforward! I’ve suggested that we take another look with the scanner next week!

RE: Nephrolithiasis in a 7yr old cat

Anthony Dennison — Thu, 23 Apr 2020 09:18:04 GMT

[quote userid="16471" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/221996"]

It's perfectly possible to SUB with a small pelvis even without fluoroscopy.

pubmed.ncbi.nlm.nih.gov/.../

You can do it intra-operative ultrasound guided.

[/quote]

I can confirm this - Roger has placed one at our practice using ultrasound as we don't have fluoroscopy.

RE: Nephrolithiasis in a 7yr old cat

Roger Wilkinson — Thu, 23 Apr 2020 08:57:30 GMT

These aren't easy. In people 90% of ureteral calculi pass spontaneously. Same is probably true in cats I suspect. There's a hint of evidence in people that prazosin helps passage of calculi. None for cats. Even more difficult if the calculi intermittently go down the ureter and then pop back up again. That's well documented in people and happens in cats too.

It's a bit of an art judging when to SUB. We've certainly seen plenty of cats with ureteral calculi without severe renal pelvis dilation. The healthier the two kidneys look the more leeway you have to allow the offending stone to pass. If you can see it going down the ureter then probably that will continue to happen until either it passes all the way through or forces you to SUB.

If contralateral kidney is very small and scarred then there's not much safety margin when the healthier kidney obstructs. Ideally would rescan and monitor azotaemia at frequent intervals.

It's perfectly possible to SUB with a small pelvis even without fluoroscopy.

pubmed.ncbi.nlm.nih.gov/.../

You can do it intra-operative ultrasound guided.

Ultimately, only time you can be really sure that a SUB would have been a good idea is when it all goes irretrievably pear-shaped.

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Wed, 22 Apr 2020 14:43:27 GMT

Sorry I must have missed that? Any reasons or references? it's pretty well standard in humans?

Any way of accessing really old discussions?.

I seem to remember there had been no trial or use in cats, not that it didn't work?

RE: Nephrolithiasis in a 7yr old cat

Anthony Dennison — Wed, 22 Apr 2020 14:03:35 GMT

[quote userid="5904" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/221977"]

Any trials or use of the human ureteral/urethral dilators of which I have only many thanks, and a few times.....until I lowered my Mg intake to near 0!

Even locally [urethra] in blocked cats??

[/quote]

You asked this question a couple of years ago and after discussion it was general consensus that they do not work in these cases.

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Wed, 22 Apr 2020 12:47:21 GMT

Mmm."raw meaty bones" mightn't be such a bad idea in cats..... or 60p 0f cats' meat from the butcher like the old days plus inflation

[FUS is my hobby-horse....]

RE: Nephrolithiasis in a 7yr old cat

gerard mclauchlan — Wed, 22 Apr 2020 12:43:25 GMT

I think it depends on what your creatinine ultimately does. Rule of thumb is most cases will have some degree of underlying CKD (hence the azotameia with unilateral obstruction). I tend to recommend stone prevention diet in IRIS stage 1 and 2 then renal diet in IRIS 3 and above. Aim for USG < 1.025 and add in potassium citrate to ensure alkaline urine if needed. Also make sure ionised calcium has been checked to exclude hypercalcaemia as a predisposing factor

RE: Nephrolithiasis in a 7yr old cat

Tom Ward — Wed, 22 Apr 2020 12:33:13 GMT

Yeah the suspicion is oxalate which cannot be dissolved and having read the acvim consensus that Jenny kindly suggested, dissolution in cats is not recommended.

i do wonder what we should do longer term about diet. I believe Hills have suggested to me previously that CD is probably a better option than KD in these cases despite early CRI.

RE: Nephrolithiasis in a 7yr old cat

Anthony Todd — Wed, 22 Apr 2020 12:22:49 GMT

[quote userid="3318" url="~/001/veterinary-clinical/small-animal/medicine/f/discussions/29047/nephrolithiasis-in-a-7yr-old-cat/221963"]ureteral obstruction[/quote]

Any trials or use of the human ureteral/urethral dilators of which I have only many thanks, and a few times.....until I lowered my Mg intake to near 0!

Even locally [urethra] in blocked cats??

RE: Nephrolithiasis in a 7yr old cat

gerard mclauchlan — Wed, 22 Apr 2020 12:07:23 GMT

95% or more of these stones are calcium oxalate so cannot be dissolved. Long term diet modification may help prevention

RE: Nephrolithiasis in a 7yr old cat

gerard mclauchlan — Wed, 22 Apr 2020 12:04:25 GMT

great news