Hyperthyroid cat - T4 control vs renal perfusion!

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Martin Atkinson — Mon, 11 Oct 2010 12:19:30 GMT

[quote user="Vikki Halliday"]

[quote user="Michael Woodhouse"]What next - everything with a heart murmur on Pimobendan because it's a heart medication and there is a heart murmur?[/quote]

That's a whole other can of worms Michael!

If you wanted a better example, why not the use of spironalactone in asymtomatic cardiac cases? Now that is food for thought.......

Personally I see nothing wrong with putting cats in moderate renal failare on and ACE inhibitor, and rarely if ever manage to get a decent sample to measure proteinuria. I know its not "on the data sheet", but then there is less and less on them these days!

[/quote]

Michael: I would very seriously consider putting dog breeds at risk of DCM with heart murmurs onto pimobendam and cats with heart murmurs onto ACEi on the basis of my research which reveals that a significant percentage of cats with cardiac murmurs will suffer sudden heart failure or thrombo-embolic disease especially with raised or rapidy rising NT-proBNP levels (both species).

Vikki: Wholeheartedy agree but NB use of Fortekor is indicated in Novartis' data sheets for cats with renal disease regardless of proteinuria - but then we've had this argument before.

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Jamie Walker — Mon, 11 Oct 2010 11:23:52 GMT

Hi,

I’m one of the Veterinary Technical Advisors at Dechra Veterinary Products and it’s certainly been very interesting to read this thread. How to best manage cats with concurrent hyperthyroidism and renal dysfunction is definitely a common challenge, with 17-49% of hyperthyroid cats reported to become azotaemic within 6 months of commencement of treatment of hyperthyroidism (Williams et al (2010) JVIM 24: 1086-1092).

We would echo the advice of previous posters – i.e. achieve a balance between control of hyperthyroidism and maintenance of adequate renal function. You should aim to achieve the best control of the hyperthyroidism you can, whilst maintaining a mild, stable azotaemia at a level that doesn’t make the cat unwell. The T4 level at which this can be achieved will be different in different cats.

Because Felimazole dose adjustments can be made in small increments of 2.5mg, this does give you a degree of flexibility when searching for this balance. If anyone has any questions on Felimazole and the management of hyperthyroid cats, or queries about any of our other products, please contact us by phone (01743 441632) or e-mail (technical@dechra.com).

Kind regards

Jamie Walker

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Andrew Kent — Sun, 10 Oct 2010 11:35:52 GMT

There was a fairly recent JSAP article looking at evidence base for managing kidney disease in dogs. The conclusion of this was that there was SOME evidence that ACEi will be of benefit even without protein loss/systemic hypertension. This is because it reduces glomerular hypertension through reducing vessel resistance which may slow the development of kidney disease.

As I understand it there is less evidence available for cats so it is difficult to know whether we can draw the same conclusion.

There is no doubt also that the occasional cat will be worse on benazepril rather than better as they are presumably utilising the glomerular hypertension in order to mainatin filtration. However to my knowledge there is no way to predict this.

I will use ACEi in cats and dogs with and without proteinuria, but I introduce it slowly building the dose up over a period of time.

Andy

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Kate Richardson — Sun, 10 Oct 2010 11:35:42 GMT

[quote user="Andre Escudeiro-Vieites"]

[quote user="Vikki Halliday"]Personally I see nothing wrong with putting cats in moderate renal failare on and ACE inhibitor[/quote]

Please, one of the medics, intervene!!

I thought it was mainly in cases of proteinuria and or hypertension, except at end stage or unstable status when it can be contraproductive due to dehydration.

On the other hand. They seem to make them feel better, so...

[/quote]

This topic was done to death in another thread (Fortekor and feline renal disease) and I think my conclusion was we will all have to agree to disagree. There may be no harm in most cases in using fortekor in all renal cases, but the debate is does it do any good?

[quote user="Laurence Webb"]

On a serious note I find that I can get a cysto sample most of the time as long as owners prepare the cat (get the sample in the morning and take any litter trays up at night so the bladder is more likley to be full). If I'm looking for a UPC and not culture or sediment exam then a voided sample from a cleaned litter tray using non-absorbant litter is fine if the bladder's empty.

[/quote]

I agree, I find I can get a cysto sample from the majority of cats- if I can feel the bladder I can cysto it. I find most cats tolerate it really well, even better than getting bloods from them in a lot of cases. I find the easiest way is to have the nurse hold the cat standing up with its back legs on the table and its back to the nurse who supports it gently under the axillae, the bladder then drops to the caudoventral abdo. I hold it steady with one hand and then using a 1 inch 23gauge needle and a 5ml syringe, stick it straight in and withdraw urine. Some cats are better lying on their side, but generally better standing. The more you do, the easier it becomes. Most owners breathe a sigh of relief when you say I can get some urine from your cat right now, or you can try to collect one at home....

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Laurence Webb — Sun, 10 Oct 2010 00:25:53 GMT

[quote user="Michael Woodhouse"]

I usually just squeeze the bladder into a kidney dish [no irony intended] conscious in the consult and dip it there and then. Usually successful and majority of cats don't mind it.

[/quote]

You're squeezing too hard! I just press hard enough to squeeze some urine into a kidney dish...

I'd also run a UPC rather than just a dipstick as they're not senisitive to low concentrations of proteinuria, especially when you're dealing with a cat that lacks concentrating ability. IDEXX do it as an add-on to a profile for £15.30 including chemistry, SG, sediment exam and culture, so you can run the biochem as well for less than £25 cost price

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Michael Woodhouse — Sat, 09 Oct 2010 20:55:09 GMT

Appreciate your reply Vikki!

[quote user="Vikki Halliday"]rarely if ever manage to get a decent sample to measure proteinuria[/quote]

I usually just squeeze the bladder into a kidney dish [no irony intended] conscious in the consult and dip it there and then. Usually successful and majority of cats don't mind it.

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Andre Escudeiro-Vieites — Sat, 09 Oct 2010 20:01:33 GMT

[quote user="Vikki Halliday"]Personally I see nothing wrong with putting cats in moderate renal failare on and ACE inhibitor[/quote]

Please, one of the medics, intervene!!

I thought it was mainly in cases of proteinuria and or hypertension, except at end stage or unstable status when it can be contraproductive due to dehydration.

On the other hand. They seem to make them feel better, so...

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Vikki Halliday LLB — Sat, 09 Oct 2010 19:37:11 GMT

[quote user="Michael Woodhouse"]What next - everything with a heart murmur on Pimobendan because it's a heart medication and there is a heart murmur?[/quote]

That's a whole other can of worms Michael!

If you wanted a better example, why not the use of spironalactone in asymtomatic cardiac cases? Now that is food for thought.......

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Michael Woodhouse — Sat, 09 Oct 2010 11:10:58 GMT

[quote user="Martin Atkinson"]I'm not. I am however surprised how anally retentive some vets are about only giving it in cases of renal disease with proteinuria.[/quote]

We were taught at college that the only evidence of any benefit of ACE inhibitors in cats with kidney disease was when they had proteinuria.

So I prescribe it based on that, not because there are other mild signs of kidney problems - it's not indicated.

What next - everything with a heart murmur on Pimobendan because it's a heart medication and there is a heart murmur?

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Martin Atkinson — Sat, 09 Oct 2010 10:51:48 GMT

[quote user="Mark Hedberg"]Fortekor's really a good choice, i'm often quite surprised at just how much of a change it makes.

[/quote]

I'm not. I am however surprised how anally retentive some vets are about only giving it in cases of renal disease with proteinuria.

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Mark Hedberg — Sat, 09 Oct 2010 00:01:51 GMT

Fortekor's really a good choice, i'm often quite surprised at just how much of a change it makes.

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Martin Atkinson — Fri, 08 Oct 2010 09:38:06 GMT

This is a very common scenario (old cats often have multiple problems), it is a balance with the balance weighted to managing the renal disease but aim to get the T4 in the middle to upper normal range if possible. I don't understand the pedantism over reserving benazpril for cats with raised UP/C ratios, IMO all old cats with raised BUN and Crea in the upper normal range should be on Fortekor and renal diet, plus phosphate binder if phos is above 1.45mmol/l (thats if the cat will tolerate it in their food which most wont). Monitor BP, not only for hyper-tension, I had one Burmese cat that went hypo-tensive once both condtions were controlled and we had to halve the dose of benazepril. SL raised an interesting point on additional fluid therapy in renal failure and I would remind people about a previous thread on skin buttons which allow clients to give fluids sub-cutaneously easily at home. I further don't understand why anyone bothers with Vidalta, IMO it is a backward step and Felimazole is a far superior product with much better flexibilty and although the data sheets say you shouldn't crush the tablets, Dechra have advised me that there is no pharmacological reason not to, it is a health and safety issue which can be resolved with sensible advice.

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Vikki Halliday LLB — Wed, 06 Oct 2010 17:32:29 GMT

I always warn owners when I diagnose a hyper T4 cat, that I will be having them back for bloods in 4-6 weeks, not just for monitoring th T4 level, but also to see if the control of the hyper T4 has "unmasked" renal disease.

I warn owners that a blood sample for renal parameters in an uncontrolled early hyper throid case are likely to be normal, and this does not unfortunately reflect the true state of renal function.

If you are lucky, and you get the hyperthyroidism early in the course of disease, you often find renal parameters are normal, however those cats which are walking twitching skeletons by the time you see them, are more likely to be suffering from renal disease as the long term raise in metabolism and blood pressure leads to renal damage.

I would echo all suggestions about renal diet, renalzin, and fortekor, and balancing the two conditions as best you can.

Re: Hyperthyroid cat - T4 control vs renal perfusion!

toby travis — Wed, 06 Oct 2010 17:26:18 GMT

I love these cases too, immensely satisfying when they go well, juggling the different diseases. I've also had an 18yo hypertensive hyperthryoid renal diabetic who was alive for >1year.

One other thing not mentioned is to keep monitoring for UTIs as I find they are quite common and usually once that is under control I don't experience that many cats who have a UP:C that necessitates the use of fortekor - I might use it if the UP:C was >0.4.

Steve - I love SQ fluids and once the owners are into it they usually love it too!

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Amanda Magrath — Wed, 06 Oct 2010 16:11:38 GMT

Thank you all for your replies on this one - very interesting points raised. I didn't realise this was such a common scenario!

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Kate Richardson — Wed, 06 Oct 2010 15:19:31 GMT

Hi Amanda

This is a very common scenario in my experience. What were his renal parameters prior to staring Vidalta? And have you looked at a urine sample to be sure the azotaemia is renal rather than pre-renal? I would suspect it IS renal, but check the SG if you haven't already. As Steve said, it is likely you have unmasked subclinical renal disease so it becomes a balancing act between the 2 diseases. If the predominant clinical signs are related to the hyperthyroidism, then aim to control those signs, but you may have to settle for a slightly higher T4 than you would normally accept to maintain renal perfusion.

Did you test his bloods on the day that he gets the vidalta or on the day he doesn't as this may affect your T4 values; best to test on the day he gets the vidalta. Intervet are really helpful if you want to give them a call about the case. You can split the tablets if you halve them cleanly eg with a pill splitter and maybe 5mg Vidalta daily will probably give smoother T4 levels and be more stable for the kidneys, I think treating every 3rd day will make his T4 control pretty erratic as you suggest.

I wouldn't read too much into the potassium level if you sent the bloods away- sample ageing will cause an artefactual increase in the potassium. You usually get hypokalaemia associated with renal disease, and occasionally with hyperthyroidism. I'd definitely check the cats BP if you are able to as HyperT and CRI are the 2 most common diseases to cause hypertension, and monitor urine protein:creatinine and use fortekor if indicated, if finances/owner allows, and start a renal diet.

It might take a little bit of playing around to find the right balance, but make sure the owner is aware that it is a balancing act and you will get gradual weight loss, but these 2 diseases can be managed concurrently in some cases for several years, as long as the cat is happy, so definitely 'treat the cat', listen to the owners in terms of how happy they feel he is on different dosing regimes. Probably try to monitor weight/urea/creat/bp every 2-3months, you may find it all stays quite stable for a surprisingly long time. I have one hyperthyroid/renal cat whose urea/creat have been at similar levels to yours for the past 3 years and he's also on metacam, amlodipine, tumil K and recently started fortekor as well as his UPC just started to creep up! So don't give up!

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Steve Leonard — Wed, 06 Oct 2010 14:41:22 GMT

Hi Amanda

My understanding of this problem is that the hyper T4 is 'masking' the renal disease not really preventing it. The increased systemic blood pressure may increase GFR therefore lowering the serum creatinine but will potentially damage the glomerulus in the longer term. Also with the decreased muscle mass in HyperT4 you may get lower than expected creatinine levels. We tend to stabilise the thyroid disease and warn owners that we may unmask renal disease and then manage that with low phosphate diets +/- binders depending on phosphate levels taken a month later. I think that you just have to accept this cat has advanced renal disease and manage that as long as you can (run UPCR to check for glomerulonephritis and add in Fortekor if present). If the owners are compliant they may consider subcut fluids given at home. They do a lot of this in the states using a giving set and needle and dripping the cat under the skin - not something I have persuaded any of our clients to do yet but supposed have good results (anyone else doing this?). And prepare owners for his inevitable demise at some point.

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Bob Russell — Wed, 06 Oct 2010 11:33:10 GMT

I will quite routinely introduce a very low dose of neomercazole where I consider there may be an issue. If they cope (and most do) vidalta can be substituted.

Renal issues are much more urgent. A cat can die as a result of renal failure in hours/days but the effects of hyperthyroidism are more long-term.

Get the renal side of things stable first and worry about T4 a bit later.

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Caroline Braidwood — Wed, 06 Oct 2010 09:50:53 GMT

I am the Product Manager for Renalzin at Bayer Animal Health and thought that you may be interested in all the free online CPD we have available that has been written by Dr Sarah Caney BVSc PhD DSAM(Feline) MRCVS, specifically about cats with kidney disease As I said its free, there is no need to register but you may find the 3 papers very useful given your queries. The papers available are:

Gold Standard treatment of renal disease patients

Laboratory diagnosis and assessment of renal function in cats

The importance of phosphate restriction in cats with CKD

http://www.renalzin.co.uk/Veterinary/Chronic-Renal-Disease/cpd.html

The link is above and hopefully you may find it useful. You can download a certificate on completion of each paper.

Kind regards

Caroline Braidwood

Re: Hyperthyroid cat - T4 control vs renal perfusion!

nikki — Tue, 05 Oct 2010 22:44:52 GMT

i tend to have these animals on renal diet and Fortekor which does help. Also tx for high BP if appropriate.

Then settle the medication level somewhere that gives a reasonable control of clin signs without panicing too much about the numbers. And make sure the owner knows it is a balancing act and one that wont last forever.

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Rob Loxley — Tue, 05 Oct 2010 21:45:15 GMT

[quote user="Amanda Magrath"]As you can't split vidalta tablets, I'm not sure how else to reduce his dose?[/quote]

Felimazole 2.5mg; Neo-mercazole 5mg?

[quote user="Amanda Magrath"]He is clinically doing very well indeed.[/quote]

Maybe treat the cat, not the blood figures?

Other thoughts: What is the likely day-to-day variation in T4, BUN and Creatinine as another thought?
Dietary management of renal insufficiency?
What is his bp?

Re: Hyperthyroid cat - T4 control vs renal perfusion!

Andre Escudeiro-Vieites — Tue, 05 Oct 2010 20:30:26 GMT

The couple of times I phoned Dechra(Felimazole) about it they were quite happy for you to give priority to renal function. Keeping the T4 a bit high wound't be so bad if it keeps renal parameters happier. Start renal diet ( +/- )P binders and, if you can check the blood pressure, and use Istin(amlodipine) and or fortekor if necessary.