VetVaultDog kidney values explained: creatinine, BUN, SDMA and IRIS stages
High creatinine in a dog means the kidneys were filtering less blood than expected when the sample was taken. Dehydration, chronic kidney disease, sudden kidney injury or a urinary blockage can cause it. Vets read it with BUN, SDMA and urine concentration, and usually repeat it, before diagnosing or staging kidney disease.
Dog kidney values at a glance
Each test answers a different question, and in dogs body build matters. The ranges below are typical, approximate examples, not cut-offs for your dog.
| Value | What it measures | Typical adult dog range (approximate) | Common non-kidney influences |
|---|---|---|---|
| Creatinine | Filtration; a muscle waste product | Upper limit often about 1.4–1.8 mg/dL (125–160 µmol/L) | Dehydration raises it; higher in Greyhounds, lower in small or thin dogs |
| BUN (or urea) | Filtration; a protein waste product | Roughly 7–27 mg/dL | Dehydration, protein meals and gut bleeding raise it |
| SDMA | Filtration | Upper limit usually 14 µg/dL | Little muscle effect; higher in Greyhounds |
| USG | How well the kidneys concentrate urine | Varies; above 1.030 is well concentrated | Diuretics, steroids and Cushing’s disease lower it |
| UPC | Protein leaking into urine | Below 0.2 | Infection, blood or inflammation in the urine raise it |
| Phosphorus | A mineral the kidneys excrete | Varies by laboratory | Growth (puppies) and damaged samples raise it |
Your report’s range comes first. Ranges differ between laboratories and analyzers, so compare your dog’s result with the range printed on its own report.
When to call the vet urgently
Call your vet or an emergency clinic immediately if your dog:
- has eaten, or may have eaten, grapes, raisins, currants or sultanas;
- may have drunk antifreeze (engine coolant);
- has swallowed human painkillers such as ibuprofen, or extra doses of its own anti-inflammatory medicine;
- has stopped eating or is vomiting repeatedly;
- is passing little or no urine, or straining to urinate;
- is suddenly weak or collapsed.
After a possible poisoning, do not wait for signs: kidney values can look normal in the first hours, and treatment works best when it starts early.
Sudden kidney injury in dogs
AKI is kidney damage over hours to days, unlike the slow decline of CKD. Some AKI recovers with prompt treatment, so speed matters. Causes in dogs listed by the Merck Veterinary Manual include:
- Grapes and raisins, including currants and sultanas. Cornell’s Riney Canine Health Center says no amount is known to be safe; vomiting often starts within 6–24 hours.
- Antifreeze (ethylene glycol). An antidote exists but must be given early.
- NSAIDs, anti-inflammatory painkillers such as human ibuprofen and naproxen, or too high a dose of a dog’s own.
- Leptospirosis, a bacterial infection spread in infected animals’ urine, often via contaminated water. It can also infect people.
The IRIS grades AKI separately from the CKD stages below.
Creatinine and BUN: what they measure
Creatinine
Creatinine is a waste product of muscle, filtered by the kidneys. It rises when the GFR (how much blood the kidneys filter each minute) falls, but it is insensitive: eClinPath notes that kidney disease pushes it above range (azotemia) only once more than about three quarters of kidney tissue is lost. Because it comes from muscle, Greyhounds and other heavily muscled dogs run higher (eClinPath cites a published Greyhound upper limit of 2.0 mg/dL), small breeds and young dogs run lower, and a thin dog can look reassuring despite reduced function. IRIS says its cut-offs apply to average-size dogs. On repeat tests, eClinPath treats a rise above 0.3 mg/dL (about 27 µmol/L) as support for falling filtration, even within range.
BUN (blood urea nitrogen) or urea
Urea is made by the liver from protein and filtered by the kidneys. A dehydrated dog reabsorbs more of it, so BUN often climbs faster than creatinine. A high-protein meal or gut bleeding raises it and liver disease lowers it, so BUN supports creatinine rather than replacing it.
Pre-renal, renal or post-renal?
| Type | Examples in dogs | Clues |
|---|---|---|
| Pre-renal (too little blood reaching the kidneys) | Dehydration, vomiting, diarrhea, blood loss, heart disease | Urine usually above about 1.030; improves with fluids |
| Renal (the kidney tissue itself) | CKD, AKI from toxins or leptospirosis, kidney infection | Urine below about 1.030 despite raised values |
| Post-renal (urine cannot leave) | Bladder or urethral stones, a ruptured bladder | Straining, little or no urine; an emergency |
These overlap: a dog with CKD that stops drinking adds a pre-renal part, so vets recheck once it is rehydrated and stable.
Addison’s disease can look like kidney disease
Addison’s disease (hypoadrenocorticism) means the adrenal glands make too little hormone. In a crisis, dehydration raises kidney values while salt loss keeps the urine dilute, which the Merck Veterinary Manual notes can mimic primary kidney disease; the azotemia typically corrects quickly with fluids. Low sodium with high potassium raises suspicion, and an ACTH stimulation test confirms it.
SDMA: an earlier marker
SDMA is released as cells break down proteins and is removed by the kidneys. IRIS and Merck describe it as less affected by lean body mass than creatinine, and Merck notes it can rise while creatinine is still normal, which helps in thin older dogs.
Caveats: IRIS bases its SDMA bands on one laboratory’s method, and other assays may not give equivalent results. SDMA can rise without reduced filtration, for example with lymphoma, and healthy Greyhounds run higher. A single mildly high SDMA calls for a recheck, not a diagnosis; it is a persistent rise that counts.
Urine specific gravity and UPC
Urine specific gravity (USG)
USG compares urine density with water (1.000). Merck states that a dehydrated dog with normal kidneys should produce urine above 1.030; in healthy, well-hydrated dogs it varies widely, so one dilute sample is not alarming on its own. In a dog with raised creatinine, urine below about 1.030 points toward a kidney cause, but diuretics, steroids, Cushing’s disease, a womb infection (pyometra) and Addison’s disease can lower it too. Unlike in cats, IRIS does not count poor concentration alone as stage 1 CKD in dogs. Ideally urine is collected before fluids are given.
UPC (urine protein:creatinine ratio)
The UPC measures protein leaking into urine, corrected for concentration, and IRIS recommends it for every dog with CKD. Merck notes that dogs with disease of the kidney’s filters (glomerular disease) can become azotemic while still concentrating urine, so protein loss may be the main clue. The test needs urine free of infection, inflammation and blood, ideally on at least two samples collected over at least two weeks.
Phosphorus and the rest of the panel
Phosphorus builds up as filtration falls. Kidney diets limit it, and the IRIS treatment recommendations for dogs set targets by stage; your vet will say whether they apply. It runs higher in puppies and in damaged (hemolyzed) samples. Vets also check potassium and red cells: anemia develops in later stages as the kidneys make less erythropoietin, the hormone that drives red cell production. Merck lists increased drinking and urination as the usual earliest signs.
IRIS CKD stages for dogs
IRIS stages CKD to guide treatment and monitoring, only after CKD is diagnosed and only in a stable, well-hydrated dog, using fasting creatinine, SDMA or preferably both on at least two occasions. It does not apply to AKI or to a dehydrated or blocked dog. The cut-offs below are from the current IRIS guidelines (modified 2026). Cats use different numbers: see cat kidney values explained.
| Stage | Creatinine (mg/dL) | Creatinine (µmol/L) | SDMA (µg/dL) | What it usually looks like |
|---|---|---|---|---|
| 1 | < 1.4 | < 125 | < 18 | No azotemia, but another kidney abnormality (kidney protein loss, abnormal imaging, rising values) |
| 2 | 1.4–2.8 | 125–250 | 18–35 | Normal to mildly raised creatinine; signs usually mild or absent |
| 3 | 2.9–5.0 | 251–440 | 36–54 | Moderate azotemia; signs beyond the kidneys may appear |
| 4 | > 5.0 | > 440 | > 54 | Rising risk of whole-body illness and uremic crises |
- SDMA and stage 1: a persistently raised SDMA (above 14 µg/dL) with normal creatinine may indicate stage 1.
- When the two disagree: IRIS stages and treats one stage higher if SDMA persistently exceeds 18 µg/dL with creatinine below 1.4 mg/dL, 35 with stage 2 creatinine, or 54 with stage 3 creatinine.
- Stage 2 can look normal: its low end sits inside many laboratories’ creatinine ranges.
Substaging by proteinuria (UPC)
| UPC (dogs) | Substage |
|---|---|
| < 0.2 | Non-proteinuric |
| 0.2–0.5 | Borderline proteinuric |
| > 0.5 | Proteinuric |
Substaging by systolic blood pressure
| Systolic pressure (mmHg) | Substage | Risk of future organ damage |
|---|---|---|
| < 140 | Normotensive | Minimal |
| 140–159 | Prehypertensive | Low |
| 160–179 | Hypertensive | Moderate |
| ≥ 180 | Severely hypertensive | High |
Nervous dogs can read falsely high, so IRIS uses several readings after the dog settles, ideally on separate visits. Sighthounds tend to run higher pressures, and IRIS prefers breed-specific ranges for them. A full result might read “stage 2, proteinuric, normotensive”.
Worked example: a borderline result in an older dog
Suppose a 10-year-old mixed-breed dog’s panel shows:
| Test | Result | Flag | On its own |
|---|---|---|---|
| Creatinine | 1.9 mg/dL (≈ 168 µmol/L) | H | Reduced filtration when sampled |
| BUN | 41 mg/dL (urea ≈ 14.6 mmol/L) | H | Supports it; dehydration can also raise BUN |
| SDMA | 21 µg/dL | H | Above the usual limit of 14 |
| USG | 1.019 | – | Less concentrated than expected |
Raised creatinine, BUN and SDMA with poorly concentrated urine fits reduced kidney function better than dehydration alone. But one snapshot does not confirm CKD, rule out sudden injury or set a stage; if CKD were confirmed, stable values like these would fall in IRIS stage 2. A vet would typically:
- Ask about exposures: grapes, raisins, antifreeze, painkillers, leptospirosis risk.
- Repeat creatinine and SDMA once the dog is well hydrated, ideally at the same laboratory.
- Run a urinalysis, then a UPC if the urine is clean.
- Measure blood pressure more than once.
- Check electrolytes, phosphorus and red cells, and possibly image the kidneys.
In a fit Greyhound with well-concentrated urine, the same creatinine can sit within the breed’s published range.
Unit conversions: mg/dL, µmol/L and mmol/L
US and Turkish laboratories mostly report creatinine in mg/dL; many European laboratories use µmol/L and report urea instead of BUN. Urea and BUN are different numbers in mg/dL, so check the label.
| To convert | Formula | Example |
|---|---|---|
| Creatinine mg/dL to µmol/L | × 88.4 | 1.9 mg/dL ≈ 168 µmol/L |
| Creatinine µmol/L to mg/dL | ÷ 88.4 | 440 µmol/L ≈ 5.0 mg/dL |
| BUN mg/dL to urea mmol/L | × 0.357 | 41 mg/dL ≈ 14.6 mmol/L |
| BUN mg/dL to urea mg/dL | × 2.14 (approximately) | 41 mg/dL BUN ≈ 88 mg/dL urea |
| Urea mmol/L to urea mg/dL | × 6.0 | 10 mmol/L ≈ 60 mg/dL |
| Phosphorus mg/dL to mmol/L | × 0.323 | 6.0 mg/dL ≈ 1.9 mmol/L |
SDMA is reported in µg/dL; USG and UPC have no units.
Frequently asked questions
What does high creatinine mean in a dog?
It means the kidneys were filtering less blood than expected when the sample was taken. Dehydration, chronic kidney disease, sudden kidney injury or a urinary blockage can all cause it, so vets interpret creatinine with urine specific gravity, SDMA and the dog's condition, and usually repeat the test.
Can grapes or raisins damage a dog's kidneys?
Yes. Grapes, raisins, currants and sultanas can cause sudden kidney injury in dogs, and no amount is known to be safe. If your dog eats any, call your vet or a pet poison control center immediately rather than waiting for signs.
What is SDMA in a dog blood test?
SDMA (symmetric dimethylarginine) is a kidney filtration marker that is less affected by muscle mass than creatinine and can rise while creatinine is still normal. It can occasionally rise for other reasons and methods are not standardized between laboratories, so vets read it together with creatinine and recheck it.
What does a high BUN mean in a dog?
BUN (blood urea nitrogen) rises when kidney filtration falls, but also with dehydration, a high-protein meal or bleeding into the gut. It is less specific than creatinine, so vets read it alongside creatinine, SDMA and urine specific gravity.
What urine specific gravity is normal for a dog?
It varies widely in healthy, well-hydrated dogs. A dehydrated dog with healthy kidneys should concentrate its urine above about 1.030, so a lower value in a dog with high creatinine suggests reduced concentrating ability, although some medicines, Cushing's disease, Addison's disease and other conditions can also lower it.
What are the IRIS stages of kidney disease in dogs?
Based on fasting creatinine: stage 1 is below 1.4 mg/dL, stage 2 is 1.4 to 2.8, stage 3 is 2.9 to 5.0 and stage 4 is above 5.0 mg/dL, with SDMA bands of below 18, 18 to 35, 36 to 54 and above 54 µg/dL. Staging only applies to a stable, hydrated dog already diagnosed with chronic kidney disease, ideally using results from at least two occasions.
Why do Greyhounds have higher creatinine?
Creatinine comes from muscle, and healthy Greyhounds tend to run higher creatinine and SDMA than other breeds. A value flagged high against a standard range may be normal for the breed, so vets interpret it alongside urine concentration and earlier results.
How do I convert dog creatinine from mg/dL to µmol/L?
Multiply the mg/dL value by 88.4. For example, 1.4 mg/dL is about 124 µmol/L, close to the 125 µmol/L that IRIS uses as the start of stage 2 in dogs. To convert back, divide µmol/L by 88.4.
Sources
- International Renal Interest Society. IRIS Staging of CKD (modified 2026) and treatment recommendations for dogs: iris-kidney.com/iris-guidelines-1; Urine specific gravity: iris-kidney.com/urine-specific-gravity
- Van Vertloo L. Renal Dysfunction in Dogs and Cats. Merck Veterinary Manual, Professional Version. merckvetmanual.com
- Addison Disease (Hypoadrenocorticism) in Animals. Merck Veterinary Manual, Professional Version. merckvetmanual.com
- eClinPath, Cornell University College of Veterinary Medicine. Azotemia. eclinpath.com/chemistry/kidney/azotemia
- eClinPath, Cornell University College of Veterinary Medicine. Creatinine. eclinpath.com/chemistry/kidney/creatinine
- Riney Canine Health Center, Cornell University College of Veterinary Medicine. Grape and raisin toxicity. vet.cornell.edu