A review of a lecture by Professor Danielle Gunn-Moore at Zoomies 2026

This lecture presents a practical, evidence-based approach to managing chronic kidney disease (CKD) in cats, structured around nine key management strategies. Drawing on decades of clinical experience and the latest research, Dr. Gunn-Moore emphasises the importance of accurate staging, early dietary intervention, appetite management, hydration, blood pressure control, proteinuria reduction, appropriate treatment of urinary tract infections, anaemia management, and long-term monitoring. The message throughout is that with systematic care, these cats can live significantly longer, high-quality lives, and that each patient requires individualised, evolving treatment plans.

1. Accurate Staging Is the Foundation of Management

Chronic kidney disease affects approximately 10% of all cats, with prevalence rising to 30% or more in cats over 12 years of age. The International Renal Interest Society (IRIS) guidelines provide the essential framework for staging and monitoring.

The staging process involves:

• Serum creatinine concentration (though this only rises after 75% of kidney function is lost)
• SDMA (symmetric dimethylarginine), which increases when function drops by 25-40%, making it a more sensitive early marker
• Important caveat: some breeds, particularly Birmans (and Ragdolls due to their Birman heritage), have naturally higher creatinine and SDMA levels. Approximately 20% of Birmans live with elevated values that are normal for them. In these cats, urine-specific gravity above 1.045 indicates normal kidney function despite elevated blood values

IRIS stages and median survival times:

• Stage 1: No azotaemia, but evidence of kidney damage (stones, previous UTI, etc.)
• Stage 2: Mild azotaemia; median survival over two years
• Stage 3: Moderate azotaemia (creatinine > 250 µmol/L); median survival approximately one year
• Stage 4: Severe azotaemia with only about 5% renal function remaining; median survival approximately two months

Full staging also requires assessment of blood pressure, urine protein-to-creatinine ratio (UPC), and phosphate status, all of which directly influence prognosis and treatment decisions.

2. Diet Is the Cornerstone of CKD Management

Renal diets reduce production of uremic toxins, maintain potassium levels, and significantly prolong survival. The evidence is compelling: cats fed renal diets live, on average, a full year longer than cats at the same disease stage that are not fed these diets.

Key features of renal diets:

• Reduced protein and phosphorus (lowering uremic toxins)
• Increased calories (these cats are often thin)
• Increased potassium (often lost through urine)
• Added water-soluble vitamins (excreted in urine)
• Reduced sodium (to manage hypertension)
• Added omega-3 fatty acids and antioxidants
• Mildly alkalising effect

Practical prescribing considerations:

• Start early (stages 1 or 2), before cats feel nauseous and refuse food
• Wean on slowly over one to two weeks; do not expect cats to accept the new diet immediately
• Use multipurpose diets where possible (e.g. combined with hypoallergenic or joint support formulations)
• Wet food is preferable to dry for increasing fluid intake
• For cats that will not eat enough renal diet, or where phosphorus remains elevated, consider phosphate binders mixed thoroughly into food

Important warning: Excessive phosphate restriction can cause hypophosphataemia, leading to weakness, severe anaemia, and paradoxical hypercalcaemia. If calcium rises unexpectedly, consider stopping the phosphate binder or weaning off the renal diet to see if calcium normalises.

3. Maintain Appetite

If cats will not eat their renal diet, all other interventions are undermined. Anorexia leads to protein malnutrition, endogenous catabolism, acidosis, and worsening renal function.

Why CKD cats stop eating:

• Uremic gastritis and nausea (visible as gastric mineralisation on radiographs)
• Central effects of uremic toxins
• Poor palatability of renal diets (cats naturally prefer salt and protein)
• Pain from nephroliths or ureteroliths
• Gastrointestinal bleeding from gastritis

Strategies to maintain appetite:

• Cat-friendly handling: warm, comfortable, fear-free environment
• Tempting meals: warm food, small portions, remove uneaten food after 30 minutes
• Flat bowls to reduce whisker fatigue; raised bowls to reduce joint pain
• Feliway Optimum (facial pheromone plus appeasement pheromone) to reduce stress
• Appetite stimulants:
  • Mirtazapine: Licensed for cats; use every 2-3 days rather than daily in CKD to avoid hyperactivity and twitching
  • Allura (Capromorelin): New licensed appetite stimulant; binds to ghrelin receptors, stimulates appetite and growth hormone release, promoting weight gain; transient hypersalivation may occur (20% of cats, usually first or second dose); early studies show over 80% of cats gained weight (average 5.2% increase)
• Maropitant: For nausea control
• Vitamin B12 supplementation: Crucial because these cats lose B12 in urine and deficiency causes inappetence; supplement if levels are below 400 ng/L (reference intervals are often too low); oral or injectable forms are effective
• Feeding tubes: Nasal tubes for short-term crisis management; oesophageal tubes for cats undergoing anaesthesia (e.g. for urethral obstruction procedures) or long-term support

4. Maintain Hydration to Protect Kidney Perfusion

Dehydration reduces renal perfusion and worsens kidney injury. Ensuring adequate fluid intake is therefore essential.

Practical approaches:

• Feed wet rather than dry renal diets
• Provide constant access to fresh water
• Water fountains for cats accustomed to running water
• Raised bowls to reduce musculoskeletal discomfort when drinking
• Soup products designed for CKD cats (check for low protein and salt)
• ProPlan HydraCare: a gelatinous product that increases water intake by nearly 30% in cats that accept it
• Subcutaneous fluids: use gravity flow (not syringe pressure) to reduce discomfort; hang the bag and allow fluid to drip; excellent owner resources are available at catprofessional.com 

Monitoring: Regular weighing at home (baby scales) alerts owners to weight loss, prompting earlier intervention.

5. Control Hypertension and Proteinuria to Slow Disease Progression

Proteinuria is an independent risk factor for progressive kidney damage. In cats, the target UPC is lower than in dogs. Survival data show that cats with UPC < 0.2 have significantly longer survival than those with higher values. Dipsticks are unreliable in cats (miss up to 40% of cases); send urine for laboratory UPC measurement.

Reducing proteinuria:

• Benazepril (ACE inhibitor): Effective but may lose effect after approximately one month due to ‘ACE escape’ (tissue kinases converting angiotensin I to angiotensin II despite ACE inhibition); therefore, recheck UPC after one month
• Telmisartan (ARB, angiotensin receptor blocker): More consistently effective for proteinuria because it blocks the final pathway; preferred choice in many cases
• Avoid ACE inhibitors or ARBs in dehydrated or unstable cats; if creatinine rises by 30% after starting treatment, discontinue or reassess

Hypertension is common in CKD cats and causes target organ damage to eyes (retinal detachment, haemorrhage, blindness), brain (stroke, dementia), heart (congestive failure), and kidneys. Blood pressure should be measured consistently using the same machine, same limb, same cuff size, and at the same location, ideally with the limb at heart level.

Treatment:

• Amlodipine: Most potent and predictable antihypertensive; first-line treatment
• Telmisartan or benazepril: Useful when blood pressure is < 180 mmHg and there is no target organ damage, or when proteinuria is also present
• Combine agents in refractory cases (e.g. amlodipine plus telmisartan)

Monitoring eyes: Distant indirect ophthalmoscopy is a quick, non-stressful way to detect hypertensive retinopathy. Use a transilluminator and a 25-40 dioptre lens; smartphone adaptors are increasingly available and effective.

6. Urinary Tract Infections: When to Treat

UTIs are common in CKD cats, but distinguishing significant infection from subclinical bacteriuria is challenging. The decision to treat should be based on functional changes, not merely the presence of bacteria.

Practical decision-making:

• If the cat is straining (lower UTI signs): treat
• If culture shows heavy growth (10^6 colony-forming units): treat, even without obvious signs
• If there is a drop in urine-specific gravity, a rise in UPC, or an increase in creatinine or SDMA in the presence of bacteria: treat, as these indicate deteriorating function

Sample collection: Owners can collect urine at home using a disinfected litter box with non-absorbent litter. This is less stressful for the cat and often yields sterile samples (especially in short-haired cats). Heavy pure growth indicates true UTI; mixed growth with low levels suggests contamination, requiring in-clinic sampling.

Antibiotic duration: Current guidelines recommend shorter courses: five days for simple UTIs, seven days for complicated cases (including CKD). Re-culture after treatment is debated; if clinical signs resolve and kidney parameters stabilise, re-culture may not be necessary.

7. Manage Anaemia: The Varizen Revolution

Anaemia is common in CKD, especially by IRIS stage 4, due to reduced erythropoietin production, gastrointestinal bleeding, and renal bleeding (especially if stones are present).

Varizen (molipidestat):

• Licensed for CKD-associated anaemia in cats
• Increases endogenous erythropoietin production and improves iron homeostasis (many cats do not require additional iron supplementation)
• Over 70% of cats increase their PCV by at least 5% within one month
• Palatable: approximately 90% of cats will lick it off the plate
• Metabolised in the liver; caution if liver disease is present
• Adverse effects (vomiting) are comparable to placebo; reflects underlying disease rather than drug effect
• Safety studies extend to six months

Treatment targets:

• Aim for PCV between 30-40%
• Consider treatment when PCV drops below 25-28%
• Stop once PCV reaches approximately 30%
• Monitor regularly; if PCV improves but red cells become hyperchromic, consider iron supplementation

Important caution: Sedation can artificially lower PCV (e.g. from 30% to 18%) due to splenic effects. Where possible, avoid heavy sedation for monitoring blood samples; gabapentin is acceptable.

8. Potassium and Phosphate Balance: The Delicate Interplay

Potassium is frequently low in CKD cats due to urinary losses and low dietary intake. Low potassium worsens kidney disease and causes polymyopathy (ventroflexion of the neck, weakness). Supplement when potassium drops below 4.0 mmol/L; severe hypokalaemia (below 3.0) causes pronounced weakness and can lead to respiratory failure if untreated.

Phosphate rises in most CKD cats as disease progresses. IRIS targets are lower than standard reference intervals. FGF23 is a more sensitive marker of phosphate overload than serum phosphate alone; if FGF23 exceeds 400 pg/mL, phosphate restriction is indicated even if serum phosphate appears normal.

Phosphate binders:

• Must be mixed thoroughly into food to bind dietary phosphate before absorption
• Use when renal diet alone is insufficient
• Avoid over-restriction; watch for hypophosphataemia and hypercalcaemia

9. Monitoring Is Essential: Each Cat Is Its Own Control

CKD is progressive, and treatment needs change over time. Regular monitoring enables early detection of complications and timely adjustment of therapy.

What to monitor:

• Weight: Monthly home weighing with baby scales; 5% weight loss in an adult cat is significant
• Serum creatinine and SDMA: Trends, not isolated values, are most meaningful
• UPC: Target < 0.2
• Blood pressure: Consistent technique and equipment
• Potassium and phosphate: Including FGF23
• PCV/haematocrit: For anaemia
• Urine culture: When clinically indicated or when kidney parameters change
• Clinical signs: Appetite, activity, vomiting, thirst, urination

Monitoring principles:

• Sedation alters PCV and USG; avoid heavy sedation where possible
• Collect urine from home using the disinfected litter box method to reduce stress
• Use consistent equipment and techniques for blood pressure measurement
• Record which machine, limb, and cuff size were used

Summary: The Key Take-Home Messages

1. Stage fully using IRIS guidelines, recognising breed-specific differences
2. Diet is foundational – start early, wean slowly, and use wet food where possible
3. Maintain appetite with cat-friendly practices, appetite stimulants (mirtazapine, Allura), B12, and anti-nausea drugs
4. Ensure hydration through wet food, fountains, raised bowls, and subcutaneous fluids when needed
5. Control proteinuria (target UPC < 0.2) and hypertension (target < 140 mmHg, but adjust for stress)
6. Use telmisartan as first-line for proteinuria; amlodipine for hypertension
7. Treat UTIs when function deteriorates, not merely when bacteria are present
8. Manage anaemia with Varizen; monitor PCV and iron status
9. Monitor regularly – weight, bloods, blood pressure, urine, and clinical signs – and adapt treatment as the disease evolves