New assay of GFR available for cats and dogs

Re: New assay of GFR available for cats and dogs

Sam Williams — Thu, 31 Jul 2014 15:51:37 GMT

Somewhat outside my field of expertise (and our protocol for the test does not involve sedating the patient) but these two papers : http://www.ncbi.nlm.nih.gov/pubmed/9140548 and http://www.ncbi.nlm.nih.gov/pubmed/21879980 suggest that sedation doesn't significantly change GFR

Re: New assay of GFR available for cats and dogs

Evelyn Barbour-Hill — Thu, 31 Jul 2014 15:25:19 GMT

[quote user="Laurence Webb"]If you've given a renal case some Omnipaque it would seem a shame not to X-ray the kidneys at the same time.[/quote]

Which was exactly my thought. It used to be said that radiography was a very poor way of assessing kidney function, but that was before the advent of digital radiography.

Re: New assay of GFR available for cats and dogs

Rob Davis — Thu, 31 Jul 2014 15:16:50 GMT

[quote user="Sam Williams"]dehydration can cause increases in BUN and serum creatinine not associated with renal failure[/quote]

[quote user="Sam Williams"]These factors shouldn't affect this GFR test. [/quote]

[quote user="Sam Williams"]As far as I know there is no evidence that the assay is affected by sedation or Alfaxan/Propofol.[/quote]

I'm quite sure I am misunderstanding things, but surely both dehydration and any sedation or anaesthesia are going to reduce renal blood flow which will in turn reduce GFR.....am I missing something?

Re: New assay of GFR available for cats and dogs

Sam Williams — Thu, 31 Jul 2014 12:30:51 GMT

As far as I know there is no evidence that the assay is affected by sedation or Alfaxan/Propofol. There was a paper published a few years ago in J Vet Sci about the use of dynamic CT imaging with iohexol to measure GFR in sedated dogs. The advantage of that is that you can measure GFR in each kidney independently; of course, you have to have a scanner and you have to sedate the animal, all of which brings up the cost quite a bit.

Re: New assay of GFR available for cats and dogs

Sam Williams — Thu, 31 Jul 2014 12:16:45 GMT

I guess one of the questions is how accurate you need your assessment of renal function to be. All the serum chemistry tests have drawbacks - e.g. dehydration can cause increases in BUN and serum creatinine not associated with renal failure. BUN can also be influenced by diet and GI bleeding, serum creatinine levels can be falsely decreased in animals with severe muscle wasting and falsely increased in patients with severe muscle damage. These factors shouldn't affect this GFR test.

Another question, which there is research ongoing at the moment to look at, is how good GFR is at predicting the development of CKD. If it is a good predictor, we are hopeful that we might be able to convince insurance companies to increase the age range they insure over if clients are prepared to carry out this test first.

Re: New assay of GFR available for cats and dogs

Laurence Webb — Wed, 30 Jul 2014 23:35:34 GMT

How much is this assay affected by sedation or Alfaxan/Propofol? If you've given a renal case some Omnipaque it would seem a shame not to X-ray the kidneys at the same time.

Do IRIS have any comment as to it's usefulness? I can see a place for in in IRIS stage 1 cases (the 'should I do anything' ones) if clients can be persuaded of the benefits of the cost and the time/multiple blood samples.

Re: New assay of GFR available for cats and dogs

Martin Atkinson — Wed, 30 Jul 2014 18:20:03 GMT

It seems quite involved and expensive when blood pressure, serum creatinine, BUN and phosphate along with urine SG and UPC ratios will give us almost all the information we need. I see a place for giving a prognosis in an acute kidney failure but not really for CKD which is the vast majority of our patients unless it is going to radically alter the treatment protocol which is rather limited even if you're into the cutting edge with Sementra, skin buttons, EPO and peritoneal dialysis.

Re: New assay of GFR available for cats and dogs

Sam Williams — Wed, 30 Jul 2014 17:34:18 GMT

The test involves a bolus injection of Omnipaque 300, followed by taking serum samples 2,3 and 4 hours later. We ask for 500 ul if possible, although we can work with smaller samples if they are all you can get (often the case with cats).

Quoted turnaround time is 4-6 days, which includes our analysis and interpretation by specialists at the RVC. In practice we're quicker than that (and can do specially fast jobs if needed), but we prefer to give a maximum time.

The test currently costs £150+ VAT. We hope to bring this down as the service takes off and our running costs come down, and we also offer discounts for multiple tests booked at the same time, or for patients who are re-tested (GFR can provide a good measure of how well CKD is being controlled, so we think we may see patients being retested, perhaps on a yearly basis)

Re: New assay of GFR available for cats and dogs

Martin Atkinson — Wed, 30 Jul 2014 17:13:33 GMT

Hi Sam. I think this is a most useful additional diagnostic tool as I see so many cats with renal failure plus the odd dog. No doubt the link you provided will give us the information we need but just quickly what samples are required, whats the turnaround time and what's the cost?