Urinary pH (Cat Food Formulation)
Definition
In formulating cat foods, consideration must be given to the urinary pH of cats, which is measured on a scale of 0 to 14 and reflects the acidity or alkalinity of the urine. The pH of a cat’s urine is greatly affected by the minerals in the food (magnesium, phosphorus, calcium, and sodium) as well as by the type of protein used in the formula. Healthy cats typically keep their urine in the slightly acidic to neutral range (pH 6.0 to 6.5). Food that causes the urine to become too acidic (pH less than 6.0 (acidic) can lead to the formation of Calcium Oxalate crystals as well as renal tubular acidosis. Food that causes the urine to become too alkaline (pH greater than 6.8) can cause the formation of Struvite crystals (magnesium ammonium phosphate).
Expanded Body
Feline idiopathic cystitis (FIC) and feline lower urinary tract diseases (FLUTD) annually affect 1-5% of the global feline population, with the data from India specifically citing 2024’s Clinical Audit conducted by Cessna Lifeline Veterinary Hospital in Bengaluru. Of FLUTD-afflicted cats, those that have pH imbalances of their urine can form stones comprising of struvite crystals (40-44% of all feline urinary stones) in urine that is alkaline in nature (pH above 6.8). On the other hand, there are also cats that suffer from FLUTD and can form stones in urine that is of acidic nature (pH below 6.0) comprising of calcium oxalate crystals (40-45% of all feline urinary stones). So as to prevent the formation of both struvite and calcium oxalate urinary crystals, commercial feline diets can be formulated to promote a urine pH of approximately 6.0-6.5. Some of the diet components that can be manipulated in order to achieve this include controlling for the level of magnesium (less than 0.02% DM) as well as using acidifying amino acids (e.g. methionine and ammonium chloride), as well as increasing the amount of high quality animal-derived protein.
The study by Buffington, Rogers and Morris in the Journal of Nutrition, published in 1984, was the first to quantitate the effect of commercial feline diets on urinary pH of cats. The study found that at urine pH values of 7.0–7.5 greater than 0.1% DM magnesium forms struvite crystals in adult male cats. The recent update of the Cat Food Nutrient Profiles by AAFCO in 2023 sets the maximum content of magnesium for adult life stages of cats at 0.1% DM. Most commercial urinary health cat foods are available in India, for example, Whiskas Urinary Care is available at DMart and on Amazon India. The other two products – Hills c/d Urinary Stress and Royal Canin Urinary SO – are available through pet specialty retailers like Heads Up For Tails as well as from veterinary clinics.
Quick Facts
| Metric | Value |
|---|---|
| Healthy Urine pH | 6.0–6.5 |
| Struvite Risk pH | > 6.8 |
| Oxalate Risk pH | < 6.0 |
| AAFCO Mg Max | 0.1% DM |
| FLUTD Prevalence (India) | 1–5% annually |
URINARY PH AND CRYSTAL RISK — REFERENCE TABLE
| Urine pH Range | Crystal Type Risk | Dietary Cause | Cat Food Solution | India Product |
|---|---|---|---|---|
| < 6.0 (acidic) | Calcium oxalate | Excess acidification, high protein | Reduce acidifiers, balanced protein | Hills c/d, RC Urinary SO |
| 6.0–6.5 (target) | Minimal risk | Controlled mineral content | Maintain current diet | Whiskas Urinary Care |
| 6.6–6.8 (mildly alkaline) | Struvite (early risk) | High Mg, low protein, plant-based | Increase animal protein, reduce Mg | Hills c/d, RC Urinary SO |
| > 6.8 (alkaline) | Struvite (high risk) | High Mg, alkaline minerals, dry-only | Wet food + urinary formula | Hills c/d (wet), RC Urinary |
Related Terms
Faq
Q: Does dry cat food cause urinary problems in Indian cats?
Dry cat food does not in itself cause FLUTD, but cats on 100% dry food diets tend to consume less water on a daily basis – approximately 40-50% less than on a wet food diet. If a cat does develop struvite crystals, they are more likely to form in urine with a pH of 6.8 or above, especially if the cat is receiving a diet with magnesium at .1% DM or above. Dr. Amrit Bhushan and his team at Cessna Lifeline (Bengaluru) suggest that cats with a history of urinary crystals should be fed at least one wet food meal a day, in addition to their dry food. .
Key Takeaways
- The normal range for the urine pH in felines is between 6.0 and 6.5. Higher pH levels greater than 6.8 increase the risk of struvite stones while lower pH levels less than 6.0 increase the risk of oxalate stones.
- The maximum amount of magnesium in the adult cat’s diet as specified by AAFCO is 0.1% on a DM basis to help prevent the formation of struvite crystals in the urine.
- Feline Lower Urinary Tract Disease (FLUTD) is reported to affect 1-5% of cats in India each year. Prevention of FLUTD is primarily through the management of the urinary pH by feeding an appropriate diet.
- The research went on to state that on a dry food only diet, a cat can loose up to 40-50% of their water intake. This, on its own, is enough reason to provide a source of wet food (it doesn’t have to be ‘special’) to cats who have had previous urinary problems.
