When I first saw Arlo’s bloodwork report in May, I was a little overwhelmed by all the different data points. Most were in “normal” reference range but a few were not. What are all the acronyms (BUN, SDMA, CREA CBC etc.)? Which ones are more important? After doing my own research and lots of discussions with our vets, I’ve now become more familiar with the bloodwork and urinalysis. Don’t be afraid to ask your vets if you are unsure but want to know more about the labwork results. Being more informed help us better advocate for our puppy.
Kidney Disease Staging
Renal Dysplasia and Chronic Kidney Disease are considered progressive (gets worse over time). After diagnosis, vets determine the stage of chronic kidney disease (CKD) based on bloodwork. IRIS (International Renal Interest Society) defines 4 stages of kidney disease (Stage 1 being the earliest, Stage 4 being the last, end-stage). I have also seen some literature talking about Stage 5 kidney disease. The staging is mostly based on Creatinine (CREA) and SDMA values in the bloodwork.
| Stage |
Creatinine (µmol/l) |
Creatinine (mg/dl) |
SDMA |
| 1 |
<125 |
<1.4 |
<18 |
| 2 |
125-250 |
1.4-2.8 |
18-35 |
| 3 |
251-440 |
2.9-5.0 |
36-54 |
| 4 |
>440 |
>5.0 |
>54 |
When Arlo had his first bloodwork done in May 2022, he was at stage 2 (SDMA).
Apart from the Stage, there are 2 additional sub-classifications for kidney disease:
- Is the dog proteinuric (is there protein loss in the urine)?
- This is based on Urine Protein over Creatinine (UPC) ratio in urinalysis. Normal non-proteinuric dog should have value < 0.2. >0.5 indicates proteinuric (values 0.2-0.5 are borderline proteinuric).
- Is the dog hypertensive (does the dog have high blood pressure)?
- Blood pressure of <140 mm Hg is normotensive (normal blood pressure).
In Arlo’s case, he has significant protein loss in the urine, but has normal blood pressure. If a dog is proteinuric, the vet may prescribe certain medications to reduce protein loss in the urine.
Which bloodwork numbers should I care about?
From my experience, there are two groups of metrics a dog with kidney disease should pay attention to. The first (what I am calling primary) group is more important than the second.
The reference range (a.k.a. what is “normal”) is actually based on lab tests of a large group of healthy dogs. Different labs may give slightly different ranges. I like to think of it as “90%+ of healthy dogs should have values falling within those ranges”. A value slightly above or below the range doesn’t necessarily mean the dog has an issue. Indeed, a dog’s diet and age may influence these values.
Primary:
Creatinine - Main test for determining kidney disease. An elevated value usually indicates something is wrong with the kidneys, though it could be a chronic or acute (short-term) issue.
SDMA - Another (alternate) metric determining kidney stage. NOTE: SDMA can be slightly higher in puppies. IDEXX, one of the main labs in healthcare testing, gives the SDMA normal range of 0-16μg/dL for puppies, compared to 0-14μg/dL for adult dogs. They say 96% of test results for puppies should fall within that range.
BUN - Blood Urea Nitrogen. Another important measure of kidney function. Healthy kidneys filter urea from the blood. Elevated BUN may indicate impaired kidney functioning, however, a high protein diet (and often dogs on a raw diet) may also lead to elevated BUN values even though the dog is healthy.
Phosphorus - High phosphorus levels is believed to negatively impact kidney functioning and worsen kidney disease. Extra phosphorus can remove calcium from the bones. Traditional research suggests targeting phosphorus levels to 4.5 mg/dl or lower for dogs with kidney disease. However, phosphorus is also needed for bone development in growing puppies, and phosphorus levels tend to be higher in puppies anyway. Even though Arlo had phosphorus levels above normal range (>7.0), our vets were not too concerned. We have been giving Arlo phosphorus binders (Aluminium hydroxide) to try to lower his phosphorus levels.
Secondary:
Calcium - Calcium generally has a negative relationship with Phosphorus. Dogs with high phosphorus tend to also have low Calcium. Abnormal calcium levels may also suggest (though not definitively diagnose) Addisons or Cushing’s disease.
Hematocrit/RBC - Kidney disease may cause Anemia in dogs. If a dog is anemic, Hematocrit or Red Blood Cell counts may be low. On the other hand, Hematocrit above normal levels may suggest the dog is dehydrated, and may benefit from fluid therapy.
Urinalysis
In terms of urinalysis, there are two main values I focus on:
Urine Specific Gravity - this determines how concentrated the urine is. Dogs with kidney disease often have diluted urine (USG <1.020)
UPC Ratio - Urine Protein:Creatinine Ratio. If protein is present in the urine, UPC ratio determines the extent of protein loss. This is also helpful in understanding the sub-stage of kidney disease. Normal non-proteinuric dog should have value < 0.2. UPC > 0.5 should be treated.
Urinalysis can also determine if the dog as Urinary Tract Infection (UTI). Some believe that chronic kidney disease may increase the risk of UTIs. UTIs can also cause elevated kidney values in the bloodwork.