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Home > Miscellaneous > Canine Kidney Disease




I have no personal experience with kidney disease in dogs, but I sometimes get asked about it, so below I explain the IRIS staging system for CKD in dogs and provide links to further information and support groups.


IRIS Staging System


When your dog is first diagnosed, you may immediatrely wonder how serious it is. Many vets now take the test results and categorise them according to the system provided by the International Renal Interest Society. This divides CKD into four stages; so if your vet tells you, for example, that your dog is in Stage 2, s/he is probably referring to the IRIS staging system.


Staging should only occur after diagnosis. Before making a firm diagnosis of CKD, two blood test readings from a stable dog who is not dehydrated (dehydration can make the numbers look a lot higher than they really are) are required. Ideally the readings should be taken after fasting, though that is not always the best choice for a CKD dog. In practice, most vets will make the diagnosis based on bloodwork taken once during your initial visit, but remember, this is not optimum. And if your dog is in crisis, perhaps severely dehydrated and on a drip at the vet's, the blood test readings will not be accurate, so do not panic.


IRIS staging of CKD (2019) International Renal Interest Society) looks at three things in this order:

  • blood tests

  • proteinuria (levels of protein in the urine)

  • hypertension (high blood pressure)

IRIS Staging System: Blood Tests

The IRIS staging system begins by looking at the dog's creatinine levels (creatinine is a measure of kidney function). Here are the four stages, together with my estimate of the likely percentage of function lost at each stage:


Stage of Disease

Blood Values:

US Measurements (mg/dl)

Blood Values:

International Measurements (Ámol/L)

Approx. Level of Kidney Function Lost

Stage 1

Creatinine below 1.4

Creatinine below 125

 0 - 65%

Stage 2

Creatinine between

1.4 and 2.8

Creatinine between

125 and 250


66 - 75%

Stage 3

Creatinine between

2.9 and 5.0

Creatinine between

251 and 440


76 - 90%

Stage 4

Creatinine over 5.0

Creatinine over 440

Over 90%


Obviously, not every dog with creatinine below 1.4 mg/dl (US) or below 125 Ámol/L (international) has CKD! The problem is that when measuring creatinine, you cannot detect CKD until at least 66% of function has been lost, because before that there are usually no symptoms (see What Happens in CKD). Therefore for dogs in Stage 1 who do have CKD, bloodwork values are usually within the normal range, and kidney problems would only be suspected if an anatomical or functional abnormality had been detected, or if the SDMA test result indicates a problem (see immediately below).


IRIS Staging: SDMA

The staging system also looks at SDMA, which is a newer test introduced by Idexx in 2015/2016. This test appears to be able to detect CKD earlier than the traditional bloodtests (see Early Detection), in some cases it may be able to detect CKD when perhaps only 40% of kidney function has been lost.


Stage of Disease


SDMA Measurement


Stage 1

Below 1.4 mg/dl

Below 125 Ámol/L

Below 18

If SDMA is increasing or is consisently above 14, CKD may be present.

Stage 2

1.4 - 2.8 mg/dl

125 - 250 Ámol/L

18 - 35

This is considered by IRIS to be mildly increased.

Stage 3

2.9 - 5.0 mg/dl

251 - 440 Ámol/L

36 - 54


Stage 4

Over 5 mg/dl

Over 440 Ámol/L

Over 54



For dogs with persistently elevated SDMA readings, IRIS staging of CKD (2019) International Renal Interest Society suggests changes in the stage of CKD the dog is deemed to be in as follows:


Creatinine Level

Current IRIS Staging

Based on Creatinine Levels

SDMA Measurement


IRIS Staging

Below 1.4 mg/dl

Below 125 Ámol/L

Stage 1

Over 18

Stage 2

1.4 - 2.8 mg/dl

126 - 249 Ámol/L

Stage 2

Over 35

Stage 3

2.9 - 5.0 mg/dl

250 - 440 Ámol/L

Stage 3

Over 54

Stage 4


In all cases, two readings in a stable dog (who is not dehydrated - this can make the numbers look a lot higher than they really are), ideally after fasting (though that is not always the best choice for a CKD patient), are required before making a firm diagnosis of CKD. In practice, most vets will make the diagnosis based on bloodwork taken once during your initial visit.


IRIS Staging System: Proteinuria


IRIS staging of CKD (2019) International Renal Interest Society then recommends sub-staging based on whether proteinuria is present.


Healthy dogs only have tiny amounts of protein in their urine because their kidneys do not allow the protein to leak through. In CKD dogs, this mechanism can be faulty and excess levels of protein in the urine, known as proteinuria but sometimes referred to as microalbuminuria, may occur.


The usual way to determine if a dog has proteinuria is via the urine protein:creatinine ratio (UPC). Three urine samples should be collected over a mimimum period of two weeks before a conclusion is drawn.


Urine Protein: Creatinine Ratio

Proteinuria Status

Below 0.2

Non Proteinuric (NP)

Between 0.2 and 0.5

Borderline Proteinuric (BP)

Over 0.5

Proteinuric (P)


There is a correlation between the severity of proteinuria in cats and the prognosis, though I don't know if the same applies to dogs. Survival of cats with naturally occurring chronic renal failure is related to severity of proteinuria (2006) Syme HM, Markwell PJ, Pfeiffer D & Elliott J Journal of Veterinary Internal Medicine 20 pp528ľ535 found that cats with a urine protein:creatinine ratio below 0.5 survived almost three times as long as cats with a urine protein:creatinine ratio of over 0.5.


However, don't panic if your dog's level is over 0.4 because the UPC ratio is not always accurate - for example, blood in the urine, infection or inflammation may give a false positive result. Hypertension may worsen proteinuria, so getting blood pressure under control may lead to an improvement in the UPC ratio. Even if your dog's UPC ratio is indeed high, it may gradually reduce with treatment.


IRIS Staging System: Hypertension

IRIS staging of CKD (modified 2019) (2019) International Renal Interest Society then recommends substaging based on whether hypertension is present. It considers a cat's blood pressure in terms of how likely it is that damage to organs such as the eyes will be caused:


Average Systolic Blood Pressure Measurement (mmHg)

Risk  of Damage

to Organs

BP Substage

Treatment Plan

Under 140



No treatment necessary

150 - 159


Borderline hypertension

Treatment is not normally necessary. However, it may be appropriate to begin or increase blood pressure medications if ocular or neurological signs are present

160 - 179



Begin or increase blood pressure medications

Over 180


Severe hypertension

Begin or increase blood pressure medications


Some dog breeds, such as sight hounds, tend to have higher blood pressure naturally. For these breeds, IRIS recommends using breed-specific reference ranges if possible.




Treatment recommendations for CKD in dogs (2019) International Renal Interest Society has some treatment suggestions for CKD dogs.


Dietary guidelines for dogs with chronic kidney disease (2018) Rollins AW Today's Veterinary Practice Jul/Aug 2018 discusses dietary issues for CKD dogs




K9Kidneys is a group for those with a dog with CKD.


K9 Kidney Diet is a group which discusses the role of diet in CKD dogs.


More Information


PetCoach has an overview of kidney disease in dogs.


Canine chronic kidney disease: current diagnostics and plan for long-term management (2013) Foster JD Today's Veterinary Practice 3(5) pp21-26 has a detailed overview of CKD in dogs.




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This page last updated: 13 July 2020


Links on this page last checked: 13 July 2020






I have tried very hard to ensure that the information provided in this website is accurate, but I am NOT a vet, just an ordinary person who has lived through CKD with three cats. This website is for educational purposes only, and is not intended to be used to diagnose or treat any cat. Before trying any of the treatments described herein, you MUST consult a qualified veterinarian and obtain professional advice on the correct regimen for your cat and his or her particular requirements; and you should only use any treatments described here with the full knowledge and approval of your vet. No responsibility can be accepted.


If your cat appears to be in pain or distress, do not waste time on the internet, contact your vet immediately.



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