Kidney disease in dogs and cats is no longer just about “high creatinine and renal diet.”
Globally, nephrology is moving toward earlier detection, stricter staging, and multi target management.
As first line clinicians, we are expected to understand not only how to diagnose chronic kidney disease (CKD) and acute kidney injury (AKI), but also how to apply newer tools like SDMA, telmisartan, and IRIS AKI grading in daily practice.
This article is written for you as a vet. Practical, clinic focused, and aligned with current global trends.
1. Rethinking how we define and stage kidney disease
CKD: still IRIS, but now more complete
Most current guidelines revolve around IRIS CKD staging for dogs and cats:
- Stage 1 to 4 based on fasting serum creatinine and SDMA
- Substaging based on:
- Proteinuria (UPC)
- Systemic blood pressure (hypertension risk category)
The key shift is this: we are no longer allowed to look at creatinine alone. A “kidney work up” should now routinely include:
- Creatinine and BUN
- SDMA
- Urinalysis with UPC
- Blood pressure measurement
Even a “normal creatinine” does not rule out early CKD if SDMA is trending up, urine is isosthenuric, or proteinuria is persistent.
2. Early detection: SDMA and the “pre CKD” patient
SDMA has become a standard part of early screening in many practices because it reflects GFR more sensitively than creatinine in some patients. The typical scenario:
- Older cat or dog
- Normal creatinine
- Slightly increased SDMA
- Maybe borderline urine changes
Globally, the trend is to treat this group as early or pre clinical CKD rather than “normal but old.” That means:
- More frequent monitoring
- Earlier diet changes
- Earlier attention to blood pressure and proteinuria
You do not need to “wait for creatinine to rise” before considering renal support.
3. CKD management: from single organ to whole system
3.1 Renal diet is still the strongest weapon
Despite all the new drugs, renal diet remains the most powerful intervention with solid evidence:
- Restricted but high quality protein
- Restricted phosphorus
- Omega 3 fatty acids
- Adjusted sodium
Start renal diets early:
- From IRIS Stage 2
- Or earlier if SDMA and UPC suggest evolving CKD
For many cats, starting a renal diet before they become obviously sick is the difference between a short uremic course and a much longer, better quality life.
3.2 Proteinuria and RAAS blockade: telmisartan era
Control of proteinuria is a major global focus because it is strongly associated with faster CKD progression.
Key points for small animal practice:
- Persistent UPC
- Cats: UPC ≥ 0.4 is already significant
- Dogs: UPC ≥ 0.5 is significant
- Treat sustained proteinuria, not just “very high” values
Telmisartan (an angiotensin receptor blocker) is now widely used:
- In cats with CKD
- Reduces proteinuria
- Helps with systemic hypertension
- Often used at about 1 mg/kg PO once daily
- In dogs with glomerular disease or proteinuric CKD
- Used around 1 mg/kg PO once daily
- Sometimes titrated upward with careful monitoring
In many countries, telmisartan is overtaking ACE inhibitors as first line in proteinuric CKD cats. For dogs, it is either used alone or as an alternative when ACE inhibitors are not enough or not tolerated.
Practical approach in clinic:
- Confirm persistent proteinuria with repeat UPC
- Start RAAS blockade
- Recheck:
- UPC
- Creatinine and SDMA
- Potassium
- Blood pressure
Avoid jumping immediately into dual blockade (ACE inhibitor plus ARB) unless you are experienced and have close monitoring, because the risk of azotemia and hyperkalemia is higher.
3.3 Blood pressure control as a progression modifier
Hypertension is not just a comorbidity. It is a driver of further kidney damage and a cause of ocular and neurologic events.
Targets usually aim for:
- Systolic blood pressure below 140 mmHg when possible
- At least below 160 mmHg to reduce risk
Common strategies:
Cats
- Amlodipine as first line for significant hypertension
- Telmisartan added if there is proteinuria or if extra BP control is needed
Dogs
- ACE inhibitor or ARB plus amlodipine if required
Blood pressure should be measured in every CKD patient at every visit. A kidney consult without a blood pressure reading is now considered incomplete medicine.
3.4 Beyond creatinine: phosphorus, acidosis, anemia, and hydration
Modern CKD management uses a checklist:
Phosphorus
- Keep within IRIS target range for each stage
- If renal diet is not enough, add phosphate binders
Metabolic acidosis
- Monitor bicarbonate or total CO₂
- Give alkalinizing therapy if levels are low
Anemia
- Investigate iron status, GI loss, chronic inflammation
- Consider erythropoiesis stimulating agents in severe, symptomatic cases
Hydration
- Encourage water intake, use wet food
- Subcutaneous fluids as needed in advanced stages
This checklist style management is where global practice is heading. It turns a vague “renal case” into a structured treatment plan.
3.5 Drug dosing in CKD: avoid adding damage
Kidney patients do not handle many drugs the way normal animals do. Key reminders:
- Reduce doses or increase intervals for drugs that are renally excreted
- Avoid nephrotoxins such as NSAIDs, aminoglycosides, and unnecessary contrast agents
- Use formal dosing tables that classify recommendations by IRIS stage
This is not only about efficacy. It is about avoiding iatrogenic kidney injury in already compromised patients.
4. Acute kidney injury (AKI): the IRIS AKI era
4.1 Grading AKI properly
The newer IRIS AKI guidelines give a structured way to classify AKI based on:
- Creatinine at presentation
- Change in creatinine over 48 hours
- Urine output
- Clinical context and risk factors
Grades go from at risk or mild to very severe. The point is to recognize AKI early, rather than waiting for extremely high values.
Common triggers include:
- Sepsis
- Pancreatitis
- Nephrotoxic drugs
- Shock or major surgery
- Infectious diseases such as leptospirosis
Once you suspect AKI, you manage aggressively.
4.2 Modern AKI management principles
Core elements:
Optimize IV fluids
- Correct dehydration
- Avoid volume overload
- Monitor body weight, urine output, and lung sounds
Diuretics for oliguria
- Used only to try to convert oliguria to non oliguria
- Not a replacement for fluid therapy
Dialysis and extracorporeal therapies
- Considered earlier in severe grades
- Useful for toxin related AKI and refractory fluid overload or hyperkalemia
Strict nephrotoxin avoidance
- Stop or avoid potentially damaging drugs
The global trend is to use IRIS AKI grading to decide when to refer for dialysis and when to hospitalize versus carefully manage as an out patient.
5. Human nephrology trends that may shape our future
In human medicine, CKD management is rapidly evolving with:
- SGLT2 inhibitors (dapagliflozin, empagliflozin)
- Non steroidal mineralocorticoid receptor antagonists such as finerenone
- Combination therapy on top of ACE inhibitor or ARB
These agents have strong evidence for slowing CKD progression and improving cardiovascular outcomes.
They are not yet standard in dogs and cats, but many veterinary nephrologists are watching this space. It is likely that future studies will explore similar mechanisms in small animal patients, especially for proteinuric kidney disease.
6. How to upgrade your own kidney protocols starting tomorrow
If you want to align your practice with current global trends, you can start with a few concrete changes:
- Standardize CKD work ups
- Always include creatinine, SDMA, urinalysis with UPC, and blood pressure
- Use IRIS staging and substaging
- Write the stage and the substaging in your records and on the discharge sheet
- Start renal diets early
- Do not wait for advanced azotemia
- Treat proteinuria and hypertension aggressively
- Consider telmisartan and amlodipine as needed
- Monitor UPC, creatinine, SDMA, potassium, and BP regularly
- Adopt a CKD checklist
- Phosphorus control
- Acid base balance
- Anemia management
- Hydration plan
- Train the team on AKI recognition
- Teach nurses and junior vets to flag rising creatinine, oliguria, recent nephrotoxin use, and at risk patients
- Develop a referral plan for dialysis cases
- Identify where you will send severe AKI or advanced CKD patients who might benefit from extracorporeal therapies
By systematizing your approach to kidney disease, you turn a difficult, emotionally charged diagnosis into a structured chronic care plan. This not only improves outcomes. It also builds deeper trust with your clients, who can see that you are following a clear, evidence based protocol.
Dr. Geoff Carullo is a Fellow and the current President of the Philippine College of Canine Practitioners.
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