FUNCTIONAL HEALTH GUIDE -- CHRONIC KIDNEY DISEASE IN CATS

FUNCTIONAL PET HEALTH -- Chronic Kidney Disease (CKD) in Cats

A Functional, Longevity-Focused Approach by Dr. Kevin Toman, The Longevity Vet.

Why CKD Deserves a Different Conversation

Chronic kidney disease (CKD) is the most common chronic disease of aging cats and one of the most misunderstood. What matters most is not simply whether a cat has CKD, but:

How early it is detected
How thoughtfully inflammation, blood pressure, protein loss, and nutrition are managed
How carefully biomarkers are followed over time

CKD is progressive—but the slope of progression is highly modifiable.

Frequency, Impact, and Prognosis

~30% of cats over age 10 show evidence of CKD
50–80% of cats over age 15 are affected
Many cats with early-stage CKD live years longer than expected with appropriate care

Early detection and functional management consistently outperform late, crisis-based intervention.

IRIS Staging: The Clinical Framework That Guides Strategy

The IRIS staging system allows us to align treatment intensity with disease severity and progression risk.

Stage 1:
Normal creatinine; abnormal urine concentration, SDMA, or protein
This is where longevity gains are greatest
Stage 2:
Mild azotemia, often asymptomatic
Ideal stage for aggressive anti-inflammatory and renal-protective strategies
Stage 3:
Moderate renal insufficiency with clinical signs
Goal: slow decline, preserve appetite, maintain weight and hydration
Stage 4:
Advanced renal failure
Goal: comfort, symptom relief, and quality of life

Functional Biomarkers: Seeing CKD Before It Becomes Obvious

Traditional blood tests detect CKD late. Functional medicine focuses on renal reserve and trajectory.

Core Biomarkers

Urine Specific Gravity (USG): earliest marker of declining concentrating ability
Urine Protein (UPC or dipstick): predictor of progression
SDMA: rises with ~25–40% nephron loss
Cystatin-C: emerging early marker of reduced GFR
Creatinine/BUN: late indicators

How Early Can We Detect CKD?

Test	Approx. Kidney Function Lost	Clinical Meaning
Urine Specific Gravity	20–30%	Earliest warning
Proteinuria (UPC)	~30%	Accelerates damage
SDMA	25–40%	Early blood marker
Cystatin-C	30–40%	Early GFR decline
Creatinine	65–75%	Late diagnosis
BUN	70–75%	Late, nonspecific

Urine testing is not optional in cats. It is foundational.

Mandatory Risk Factors and Rule-Out Conditions

Every cat with suspected or confirmed CKD must be evaluated for:

Hypertension

Common, silent, and destructive
Worsens kidney damage and accelerates decline
Requires proper feline measurement technique

Heart Disease (Especially HCM)

Cardiac output directly affects renal perfusion
Kidney disease promotes hypertension and cardiac remodeling

Dental Disease

Chronic oral inflammation increases systemic inflammatory burden
Proven contributor to renal progression

Hyperthyroidism

Increases GFR and masks CKD
Treatment often reveals underlying renal disease
Must be identified and managed concurrently

The Heart–Kidney Axis: HCM and CKD

The heart and kidneys function as a linked system.

Reduced cardiac output worsens renal perfusion
CKD increases blood pressure and cardiac workload
Management decisions must balance both organs

Medication Interactions

Furosemide (Lasix): lifesaving for heart failure but increases dehydration risk
ACE inhibitors / ARBs: reduce proteinuria and hypertension but require monitoring
Serial blood pressure, renal markers, and hydration assessment are mandatory

Supplements: Targeting Inflammation and Fibrosis

Functional CKD care focuses on reducing inflammatory signaling and slowing fibrotic change.

Fish Oil (Omega-3 Fatty Acids)

One of the most important interventions in feline CKD.

Benefits:

Reduces renal inflammation
Slows glomerular fibrosis
Supports cardiovascular health
May reduce proteinuria

High-quality, purified marine sources are preferred. Dose must be appropriate for cats.

Additional Supportive Supplements

Anti-inflammatory and antioxidant compounds (used judiciously)
Phosphorus binders when indicated
Support for appetite, hydration, and gut health as disease progresses

Supplements should always be biomarker-guided, not generic.

Prescription Medications: Protecting Remaining Renal Function

ACE Inhibitors / ARBs

Indicated for:

Proteinuria
Hypertension
Glomerular protection

Benefits:

Reduce intraglomerular pressure
Slow progression in protein-losing cats
Improve long-term renal outcomes

Monitoring is essential to ensure kidney values remain stable.

Rapamycin: A Promising Longevity-Focused Therapy

Rapamycin is a potent anti-inflammatory and anti-fibrotic agent with proven longevity benefits across mammalian species.

In cats:

Reduces systemic inflammation
May protect renal microvasculature
May benefit concurrent cardiac disease (especially HCM)

Rapamycin is currently under study at two U.S. veterinary schools for feline kidney and heart disease. While not yet standard of care, it represents a next-generation longevity tool when used carefully and under veterinary supervision.

Dietary Therapy: Modern Thinking for Aging Cats

What We No Longer Recommend

Severe protein restriction
Weight loss in senior cats
Prioritizing lab numbers over body condition

What We Aim For Instead

Adequate protein intake
High biologic value protein
Weight and muscle maintenance

Protein quality matters more than protein quantity.

Approximate biologic value hierarchy:

Fish > poultry > eggs > red meat

Additional goals:

Moderate phosphorus control
High moisture content
Excellent palatability

A cat that maintains weight and appetite lives longer.

One-Page Early Detection Decision Tree (Integrated)

Feline CKD Early Detection & Action Pathway

Cat ≥7 years OR any age with risk factors

⬇️
Step 1: Urinalysis

USG ≥1.035 → monitor annually
USG <1.035 → proceed

⬇️
Step 2: Urine Protein Assessment

Protein negative → continue evaluation
Protein positive → UPC + blood pressure

⬇️
Step 3: Blood Biomarkers

SDMA ± cystatin-C
BUN/creatinine baseline

⬇️
Step 4: Rule-Outs

Blood pressure
Total T4
Cardiac assessment
Dental exam

⬇️
Step 5: Stage (IRIS) + Functional Plan

Diet optimization
Supplements (fish oil first-line)
ACE inhibitor if proteinuric or hypertensive
Longitudinal biomarker tracking every 3–6 months

Prognosis and Longevity

CKD is not a death sentence.

Early-detected cats often live many additional high-quality years
Progression can be slowed dramatically
Quality of life is usually excellent when inflammation, nutrition, and blood pressure are controlled

The most important variable is how early the disease is recognized and how thoughtfully it is managed over time.

Final Message to Cat Parents

Cats are quiet sufferers and brilliant compensators. Functional medicine allows us to listen before the crisis, intervene before the damage is advanced, and protect what matters most—time, comfort, and dignity.