FLUTD and Urinary Crystals in Cats: Signs, Diet and Prevention

Urinary problems are among the most painful and distressing conditions a cat can experience — and one of the most common reasons for emergency vet visits in the UK. Straining to urinate, frequent trips to the litter tray that produce very little, or crying out while trying to go are signs that something is wrong and needs to be addressed quickly.

The good news is that diet plays a direct and significant role in both the prevention and long-term management of feline urinary issues. This guide explains what FLUTD is, which cats are at highest risk, how diet affects urinary health, and when our Urinary Health recipe is the right choice — as well as when you need urgent veterinary attention.

All three Ultimate Plus Cat recipes use hydrolysed protein as the primary protein source. If you are new to the concept, our complete guide to hydrolysed cat food explains the process and why it makes such a measurable difference for cats with specific health conditions.

What Is FLUTD?

Feline Lower Urinary Tract Disease (FLUTD) is an umbrella term for a group of conditions affecting the bladder and urethra. It is not a single disease but a collection of issues that share similar symptoms. The most common forms include:

• Struvite crystals: Mineral deposits that form in the bladder when urine pH is too alkaline. The most common type in cats, and directly influenced by diet.
• Calcium oxalate crystals: Form in acidic urine and are more common in older cats. These are harder to dissolve through diet alone and may require other veterinary treatment.
• Feline idiopathic cystitis (FIC): Bladder inflammation with no identifiable physical cause — stress is considered a major contributing factor.
• Urethral obstruction: A blockage of the urethra, most common in male cats, that is a life-threatening emergency requiring immediate veterinary treatment.

Signs of Urinary Problems in Cats

Recognising the signs early can prevent serious complications. Watch for:

• Frequent visits to the litter tray with little or no urine produced
• Straining or appearing to be in pain when urinating
• Blood in the urine (pink-tinged or red)
• Urinating outside the litter tray — often on cool surfaces such as tiles or baths
• Excessive licking of the genital area
• Lethargy or loss of appetite alongside urinary signs
• A hard or distended abdomen in a male cat — a possible sign of obstruction requiring emergency care

Which Cats Are Most at Risk?

FLUTD and urinary crystal formation are significantly more common in certain populations:

• Sterilised and neutered cats — hormonal changes affect metabolism and increase the risk of weight gain and urinary issues
• Indoor cats — lower activity levels and reduced water intake lead to more concentrated urine
• Middle-aged cats — most commonly seen between 2 and 6 years of age
• Overweight cats — excess body weight is associated with increased FLUTD risk
• Cats fed primarily dry food — lower moisture intake increases urinary concentration
• Male cats — at significantly higher risk of urethral obstruction due to a narrower urethra

How Diet Directly Affects Urinary Health

Urine pH

Struvite crystals form when urine is too alkaline. Maintaining a slightly acidic urine pH — between 6.0 and 6.5 — prevents struvite formation and can help dissolve existing crystals. Many commercial cat foods, particularly those high in plant-based proteins, push urine pH in the wrong direction.

Magnesium Content

Magnesium is a key mineral component of struvite crystals. A diet with controlled, appropriately low magnesium levels reduces the raw material available for crystal formation. This is a standard consideration in urinary management diets.

Hydration

Concentrated urine creates the chemical conditions for crystal formation. Increasing your cat’s overall fluid intake dilutes the urine and significantly reduces crystal risk. Ensuring fresh water is always available and using a water fountain alongside a urinary-appropriate diet are both important steps.

When Will Our Urinary Health Recipe Help?

Our Hydrolysed Cat Food — Urinary Health features our exclusive UriTract blend — a targeted combination of ingredients designed to maintain optimal urine pH and support long-term urinary tract health, using hydrolysed chicken as the primary protein source.

This recipe is likely to produce a meaningful improvement if your cat:

• Has been diagnosed with struvite crystals and your vet has recommended a urinary management diet
• Has had a previous episode of FLUTD and you want to reduce the risk of recurrence
• Is a sterilised indoor cat at elevated risk of urinary issues
• Shows mild or occasional urinary symptoms (going more frequently, small amounts) with no obstruction or blood present
• Is currently on a prescription urinary diet and you want a non-prescription equivalent formulated to the same clinical standard

In independently conducted feeding trials, 90% of cats achieved optimal urine pH within the target range. Most owners notice improved urinary comfort and frequency within 3–4 weeks of fully transitioning to the diet. No prescription is required.

When to See a Vet — Including Emergencies

Urinary problems in cats can escalate from uncomfortable to life-threatening within hours. The following situations require immediate or urgent veterinary attention.

Go to an emergency vet immediately if your cat:

• Has been trying to urinate for more than 2–3 hours without producing any urine at all
• Has a hard, painful, or visibly distended abdomen
• Is crying out in pain, is unusually still, or is sitting in a hunched position
• Is vomiting alongside urinary straining
• Is a male cat completely unable to urinate — this is a life-threatening emergency

A urethral obstruction can be fatal within 24–48 hours if untreated. Do not wait and see.

See your vet within 24 hours if your cat:

• Has visible blood in the urine
• Has been straining repeatedly but is still passing some urine
• Has gone off food or appears lethargic alongside urinary signs

A dietary change is appropriate when: your cat has mild, recurring urinary symptoms with no obstruction present, or has been assessed by a vet and a urinary management diet has been recommended for ongoing prevention.

If your vet has confirmed a crystal diagnosis, it is worth asking which type — struvite or calcium oxalate — as the dietary approach differs. Our Urinary Health recipe is formulated for struvite prevention and management. Calcium oxalate crystals require a different dietary strategy.

Transitioning to the Urinary Health Diet

• Days 1–3: 75% old food, 25% Urinary Health
• Days 4–6: 50% old food, 50% Urinary Health
• Days 7–9: 25% old food, 75% Urinary Health
• Days 10–14: 100% Urinary Health

Always ensure fresh water is available. A water fountain can significantly increase daily fluid intake for cats that are reluctant drinkers — especially important when managing urinary health.

Frequently Asked Questions

Does my cat need a prescription for this diet?

No. Our Urinary Health recipe is available without a vet prescription. However, if your cat has a confirmed diagnosis, a conversation with your vet to confirm the appropriate dietary approach is always worthwhile.

Can this diet dissolve existing crystals?

A diet designed to maintain optimal urine pH can help dissolve struvite crystals over time and prevent new ones from forming. Calcium oxalate crystals cannot be dissolved through diet and may require surgical or other veterinary intervention.

My cat is male — is this diet suitable?

Yes, and it is particularly relevant for male cats given their significantly higher risk of urethral obstruction. If your male cat has had a previous blockage, a urinary management diet is one of the most important long-term preventive measures available.

Can I use this as a preventive diet even if my cat has not had urinary problems?

Yes. If your cat is a sterilised indoor cat at elevated risk, feeding a urinary health diet proactively is a well-supported preventive measure.

My cat also has a sensitive stomach — which recipe should I prioritise?

Urinary issues tend to be more urgent, so start with the Urinary Health recipe. Once urinary health is stable, you can reassess whether a change to the Digestive Care recipe is needed. Our guide to sensitive stomach in cats covers this in more detail.

Editorial note: This article is written for informational purposes only, based on independently conducted feeding trials and consultation with UK veterinary nutritionists. It is not a substitute for professional veterinary advice. Always consult your vet if you have specific concerns about your cat’s health.

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